Hi Guys,
In recent weeks I have been checking out the forums and as usual the same old topics are coming up. Do I go RO, or just change water. Do I add clay and other conditioners? What should my factors be, should I be hard or soft.
Well I pride myself on being a serious koi keeper and as many of you do, we strive for the best water quality we can achieve by whichever means we select. I have chosen to go done the RO route. For the last twelve months I have had a 300 gallon a day constant trickle into my 6000 gallon pond. I decided to take it slowly so as not to shock my fish and sure enough over the coming months I found that my water was getting softer.
Before RO (July 2010) After RO (July 2011)
PH 7.5 6.7
KH 6 0-1
GH 11 0 (now mix 4)
TDS 240 148
Now as things have settled I found that I had to buffer my water to keep any carbonates in it to allow my filters to function correctly. This is where I am starting to get concerned. At present I am finding that I am unable to keep my KH above zero for more than 24 hrs. If I use bicarb then I am getting ph and kh swings when the bicarb is added and then depleted. I feel that this cannot be the long term solution. I have then tried buffering with none ro water, at present this does not seem to be working but what ratio would work best to achieve this? One thought then comes to mind; surely I’m defeating the object if I’m adding all the bad stuff back in that I have been removing from the water with the ro? Please can anyone advise me on what the long term solution should be?
The second part of my thoughts is about the water in my pond. Surely we need to keep the water quality high by removing as many of the other potentially harmful things from the water. Assuming our filters are working to the optimum. Isn’t it better for us to try and remove the likes of Nitrates, DOC, Phosphates and all other organic matter rather than just flushing them to waste by introducing larger and larger amounts of RO water? I would appreciate your thoughts on this as it seems to be a subject that divides opinions of so many hobbyists.
Regards
Simon
Water Utopia
Moderators: B.Scott, vippymini, Gazza, Manky Sanke
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Manky Sanke
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Re: Water Utopia
Simon,
I'm not an RO user (yet) but, from a pure water chemistry point of view, you may be trying to go too far down the RO route. I'll leave RO users to talk about the ratio of RO to tapwater but if you are running with a KH of less than 1, you will always have trouble with pH swings.
Bio-filters use carbonates in great quantities. To convert 1 mg of ammonia to nitrate, the bugs will use 7.2 mg of carbonate which, if you are using bicarbonate as a buffer, equates to a little over 10 gm of bicarbonate for every gram of ammonia. If the bugs are not getting this from the tapwater, you will have to supply it yourself and also, the rate at which they use it explains why you have trouble keeping the level up for more than 24 hours. Try adding more at a time and see if that helps.
I'm not an RO user (yet) but, from a pure water chemistry point of view, you may be trying to go too far down the RO route. I'll leave RO users to talk about the ratio of RO to tapwater but if you are running with a KH of less than 1, you will always have trouble with pH swings.
Bio-filters use carbonates in great quantities. To convert 1 mg of ammonia to nitrate, the bugs will use 7.2 mg of carbonate which, if you are using bicarbonate as a buffer, equates to a little over 10 gm of bicarbonate for every gram of ammonia. If the bugs are not getting this from the tapwater, you will have to supply it yourself and also, the rate at which they use it explains why you have trouble keeping the level up for more than 24 hours. Try adding more at a time and see if that helps.
Re: Water Utopia
Simon what's the difference between your input water and your pond reading? If you're putting sure RO water in (which should have a TDS near to 0) and your pond water still has a TDS of 140 then you've got a fair amount of dissolved substances coming from somewhere.
Before you switched to RO what was the difference between the New water going in and your pond readings?
Before you switched to RO what was the difference between the New water going in and your pond readings?
Re: Water Utopia
Hi Ed,
The readings on my pond are as follows:
Tap (from purifier) - tds 205
RO unit - tds 5
Mix of above - tds 83
Summer pond level - 150
winter pond - below 100
I am trying to achieve best water quality without level swings and remove all the water nasties. I realise my setup is not right but I wanted to get this whole subject right in my head before I spend a fortune chasing the levels all around.
Cheers
Simon
The readings on my pond are as follows:
Tap (from purifier) - tds 205
RO unit - tds 5
Mix of above - tds 83
Summer pond level - 150
winter pond - below 100
I am trying to achieve best water quality without level swings and remove all the water nasties. I realise my setup is not right but I wanted to get this whole subject right in my head before I spend a fortune chasing the levels all around.
Cheers
Simon
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Manky Sanke
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Re: Water Utopia
Simon,
I won't trample too heavily into a subject where I'm only working from chemistry with no practical experience, but here is a bit of pure theory that might help you or any other RO users with the problem of varying parameters such as pH.
The key to a stable pH is to have a sufficiently high KH. RO people try to get the total dissolved stuff in their water as low as they can (dare?). Since one of the aims of RO is to promote good growth, it is probably also the case that the koi will be fed plenty of high protein food which will inevitably produce a lot of ammonia. A good bio-filter will cope with this but the bugs will use a lot of KH in the process. Running water to waste will also dilute out any KH in the water.
Your job is simple. To maintain stable parameters at whatever levels you have chosen, all you have to do is continously replace the KH at the same rate as it is being diluted out or being used by the bugs. If your pond is using, say, 1 gm of carbonate per hour, the ideal situation would be to replace it at the rate of 1 gm per hour, day and night. You will then have rock stable parameters. Of course it isn't practical to permanently sit by the pond chucking in small amounts of bicarbonate so you have to find a compromise that will be practical.
Designing water chemistry control systems is a big part of what I do for a living (when I work these days) and the first step after deciding what parameters are required is to design a system that does the job on a regular basis. Mostly that consists of continuously measuring and automatically dosing tiny amounts. That gives the most stable parameters but even a simple system of just adding a fixed amount per hour or per day can produce quite good results.
Electronically monitoring is possible but isn't practical for pH control in koi ponds, so the second semi-automatic idea for continuously topping up carbonate with tapwater or regular additions of bicarbonate are your best options.
This is where you can pinch ideas from RO users. Trickling in a continuous amount of tapwater is one strategy. Once you have sucked it and seen what amount works for your situation, this should work pretty well. Another strategy might be to add a regular amount of bicarbonate per day. Again, you could pinch some ideas or suck it and see what amount works for you.
I won't trample too heavily into a subject where I'm only working from chemistry with no practical experience, but here is a bit of pure theory that might help you or any other RO users with the problem of varying parameters such as pH.
The key to a stable pH is to have a sufficiently high KH. RO people try to get the total dissolved stuff in their water as low as they can (dare?). Since one of the aims of RO is to promote good growth, it is probably also the case that the koi will be fed plenty of high protein food which will inevitably produce a lot of ammonia. A good bio-filter will cope with this but the bugs will use a lot of KH in the process. Running water to waste will also dilute out any KH in the water.
Your job is simple. To maintain stable parameters at whatever levels you have chosen, all you have to do is continously replace the KH at the same rate as it is being diluted out or being used by the bugs. If your pond is using, say, 1 gm of carbonate per hour, the ideal situation would be to replace it at the rate of 1 gm per hour, day and night. You will then have rock stable parameters. Of course it isn't practical to permanently sit by the pond chucking in small amounts of bicarbonate so you have to find a compromise that will be practical.
Designing water chemistry control systems is a big part of what I do for a living (when I work these days) and the first step after deciding what parameters are required is to design a system that does the job on a regular basis. Mostly that consists of continuously measuring and automatically dosing tiny amounts. That gives the most stable parameters but even a simple system of just adding a fixed amount per hour or per day can produce quite good results.
Electronically monitoring is possible but isn't practical for pH control in koi ponds, so the second semi-automatic idea for continuously topping up carbonate with tapwater or regular additions of bicarbonate are your best options.
This is where you can pinch ideas from RO users. Trickling in a continuous amount of tapwater is one strategy. Once you have sucked it and seen what amount works for your situation, this should work pretty well. Another strategy might be to add a regular amount of bicarbonate per day. Again, you could pinch some ideas or suck it and see what amount works for you.
Re: Water Utopia
Why is a pH controller not a good solution in this instance?
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Gazza
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Re: Water Utopia
Hi Syd,
I am afraid i have to disagree with you young man and one of the first things i have always been asked and people always thing about RO = big fish or magic growth its a myth and defiantly not why i run RO
RO or soft water i believe is beneficial for the fish in many ways and not growth as there are many ponds out there without RO that can grow on big fish to get big fish is a much much bigger thing than just soft water. One of the reasons the growth word comes out is that in many of the systems running RO they all have a similar set up or ideas some fast turn over on the ponds they are normally showered and run RO, Then the main one is genetics but i have rattled on enough for now
OH controls can be used Ben and this can give you a very stable pond by setting the PH controller to make sure you set the controller where you want it and that where the pond will stay and this can also be done with a dosing pot and some Bi carb mix or even acid injection. The main thing is to get a stable system as said above and it can take a bit of time working out which way works best for RO users but i think most of us like playing around anyway
I am afraid i have to disagree with you young man and one of the first things i have always been asked and people always thing about RO = big fish or magic growth its a myth and defiantly not why i run RO
RO or soft water i believe is beneficial for the fish in many ways and not growth as there are many ponds out there without RO that can grow on big fish to get big fish is a much much bigger thing than just soft water. One of the reasons the growth word comes out is that in many of the systems running RO they all have a similar set up or ideas some fast turn over on the ponds they are normally showered and run RO, Then the main one is genetics but i have rattled on enough for now
OH controls can be used Ben and this can give you a very stable pond by setting the PH controller to make sure you set the controller where you want it and that where the pond will stay and this can also be done with a dosing pot and some Bi carb mix or even acid injection. The main thing is to get a stable system as said above and it can take a bit of time working out which way works best for RO users but i think most of us like playing around anyway
Re: Water Utopia
Hi Gazza,
I realise that RO is not a magic wand, but how do we achieve the balance I am hoping for in my original question. Without the PH controller it has to be manually dosed with bicarb, which can be a bit hit and miss. I have also started using a mix but surely I am only adding in the impurities I am trying to remove with the RO. I still havn't seen any science that suggests that adding clay gives any real benefit to the fish, all it seems to do is irritate their gills.
Shouldn't we be looking to remove the other things from our water that are produced naturally as mentioned above. I would appreciate your advice as I am unsure of which route is best for the future.
Cheers
Simon
I realise that RO is not a magic wand, but how do we achieve the balance I am hoping for in my original question. Without the PH controller it has to be manually dosed with bicarb, which can be a bit hit and miss. I have also started using a mix but surely I am only adding in the impurities I am trying to remove with the RO. I still havn't seen any science that suggests that adding clay gives any real benefit to the fish, all it seems to do is irritate their gills.
Shouldn't we be looking to remove the other things from our water that are produced naturally as mentioned above. I would appreciate your advice as I am unsure of which route is best for the future.
Cheers
Simon
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Manky Sanke
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Re: Water Utopia
Benyiii,
I've got nothing against pH controllers. I must have installed or maintained mill-yons of them, and in clean water they can be made to work perfectly. If the probes become contaminated, or they aren't recalibrated regularly enough, they can start pumping acid uncontrollably until either someone comes along and notices that the pool pH has taken a dive or some fancy control panel sets off an alarm in reception.
My worry would be that, in a pond, if the probes became contaminated with a bio-film, the pump might start pumping acid over-night and crash the pH. Also, there are cheap controllers but a good quality, reliable system is several hundred pounds. That seems an expensive way to achieve a stable pH, something that most pond people manage to do without an expensive machine that might go wrong and put their fish at risk. Those are the only reasons I would call them impractical.
But if you are using a pH contoller, as Gazza said, to dose a solution of sodium bicarbonate, that's much safer. Strictly, it then is no longer a pH controller but an alkalinity controller. The system will still won't be cheap, but it would be much safer. If the probes became contaminated, the worst it could do is whack in a load of bicarbonate which would only bugger up your nice low KH reading without risking the safety of the fish.
Gazza,
"Young man"? you little smoothy. I've been out all day, I've just come home stiff, aching and feeling every year of my age plus a few more, but you've just made me smile!
Anyway, as I said I'm not an RO user so I only know the chemistry angle. As for the reasons for using it, I only know what I've read. I've obviously been hoodwinked by the myth. So when I finally get round to changing over, it looks like I'll be disappointed, I was expecting a spurt of growth.
I've got nothing against pH controllers. I must have installed or maintained mill-yons of them, and in clean water they can be made to work perfectly. If the probes become contaminated, or they aren't recalibrated regularly enough, they can start pumping acid uncontrollably until either someone comes along and notices that the pool pH has taken a dive or some fancy control panel sets off an alarm in reception.
My worry would be that, in a pond, if the probes became contaminated with a bio-film, the pump might start pumping acid over-night and crash the pH. Also, there are cheap controllers but a good quality, reliable system is several hundred pounds. That seems an expensive way to achieve a stable pH, something that most pond people manage to do without an expensive machine that might go wrong and put their fish at risk. Those are the only reasons I would call them impractical.
But if you are using a pH contoller, as Gazza said, to dose a solution of sodium bicarbonate, that's much safer. Strictly, it then is no longer a pH controller but an alkalinity controller. The system will still won't be cheap, but it would be much safer. If the probes became contaminated, the worst it could do is whack in a load of bicarbonate which would only bugger up your nice low KH reading without risking the safety of the fish.
Gazza,
"Young man"? you little smoothy. I've been out all day, I've just come home stiff, aching and feeling every year of my age plus a few more, but you've just made me smile!
Anyway, as I said I'm not an RO user so I only know the chemistry angle. As for the reasons for using it, I only know what I've read. I've obviously been hoodwinked by the myth. So when I finally get round to changing over, it looks like I'll be disappointed, I was expecting a spurt of growth.
Re: Water Utopia
Syd thanks thats why i asked as i thought you might have a bit of experience with them. As it happens i have run the ro with one for a couple of years now and find it very good although it is one of the relatively expensive ones. Personally i found bicarb solution dosing impracticle as even with 200galons of solution i struggled to get enough bicarb dissolved (rather it just stuck to the sides of the container) and they were emptied nearly daily. Now i just use a solenoid on source water to dose purified tap water. This is much more belt and braces i think
Ben
Ben
Re: Water Utopia
Simon,
I know we have spoken about this on the phone and there is a sense of frustration on your part with this topic. Just about every body knows i am PRO using RO in a pond that needs it and after reading through this thread again i find myself kind of agreeing with Syd ( ) but also wanting to find a way to run this type of system to your adavantage so you stay on a road that has bought you happier healthier koi.
So a few thoughts which i have posted on another forum today also...
I think the confusion comes from it is actually quite a simple process and if you understand that all the readings are linked and react to each other then control is easier but there are no "perfect" rules on how to run it in every pond - as every pond is different. You need to find a way that suits you to get a stable PH and KH and once you do that - its simples (as the meerkat would say).
I think the worrying thing for me is that i'm hearing of quite a few cases now where people are ending up in a negative KH scenario. Whereby they cannot keep the KH to a level of balance in their filters, now the easy way to explain this is that the koi stocking level, food rate, water change rate is out of balance and the pond and its in habitants are taking stuff out of the water quicker than you are replacing it.
Answer - replace it quicker / better. (how to do so is an individual choice:- but there are options out there but your tap water dictates what they are)
This is where if i was in that kind of scenario i would be simply turning off the RO plant and getting up to a balance point that i was happy with and then beginning again. It is very easy to get sucked in to the "chasing low PH" and in fact you get too low which before you realize it in a "closed system pond" that the KH is out of stock and there is no residual KH left in the system to prop everything up. I watch the KH numbers MORE than the PH really to be honest.
why?....
Simply put by increasing the sensitivity of the drop test you can be more than accurate enough and probably more reliable than an out calibration / poor quality PH probe. Plus it is KH that prevents a PH slide (read the word crash) so if you maintain a stable KH then the rest is easy. I have found that a certain PH (eg 7) does not nessesarily mean you will have an acceptable KH value in the pond. In my pond for example if i let the KH drop under 2 then it all becomes very unstable and i get larger daily swings. Now not a huge problem IF you are there to react and stay on top of it but if you work long hours / shifts / go on holiday etc not so easy to control. So for this reason i err on the side of caution these days.
One other thing i found is that if my GH level was considerably higher than my KH (say double) when i got down low with the numbers this increased the swings. I do not know why this is the case as no-one has ever explained it to me. So i now set my KH and GH up so that they run Level (eg: KH 2 GH 2). Now i suspect that that in the perfect world i might be sacrificing something by running slightly up on the written ideals but its the best way for me to do it.
The rules you see are quite hard to quantify i think, whereby you see - change "X" % of water, have a TDS of this reading, have a KH of this level etc etc. EVERY SINGLE POND IS DIFFERENT - and it is ultimatly the pond and it inhabitants that effects the water. Find the comfort zone for your pond and go there - now this may be easier for me to do as i came from a bad place:-
PH 8+
KH 11
GH 16
TDS 440+
So for me to accept
PH 7.1 - 7.3
KH 2
GH 2
TDS around 100 - 150
is easy as it is a million miles better than where i was and the results show that. It is a lot harder to accept it if your trying to improve water of say PH 7.6 - 7.8 as the changes are minimal and you'd need a good eye to spot the difference.
Be interested to hear what you decided with this and how you reacted to the scenario. Sorry to drag the thread back up but i was on holiday when you posted it and i'm now playing catch up.
I know we have spoken about this on the phone and there is a sense of frustration on your part with this topic. Just about every body knows i am PRO using RO in a pond that needs it and after reading through this thread again i find myself kind of agreeing with Syd (
) but also wanting to find a way to run this type of system to your adavantage so you stay on a road that has bought you happier healthier koi.So a few thoughts which i have posted on another forum today also...
I think the confusion comes from it is actually quite a simple process and if you understand that all the readings are linked and react to each other then control is easier but there are no "perfect" rules on how to run it in every pond - as every pond is different. You need to find a way that suits you to get a stable PH and KH and once you do that - its simples (as the meerkat would say).
I think the worrying thing for me is that i'm hearing of quite a few cases now where people are ending up in a negative KH scenario. Whereby they cannot keep the KH to a level of balance in their filters, now the easy way to explain this is that the koi stocking level, food rate, water change rate is out of balance and the pond and its in habitants are taking stuff out of the water quicker than you are replacing it.
Answer - replace it quicker / better. (how to do so is an individual choice:- but there are options out there but your tap water dictates what they are)
This is where if i was in that kind of scenario i would be simply turning off the RO plant and getting up to a balance point that i was happy with and then beginning again. It is very easy to get sucked in to the "chasing low PH" and in fact you get too low which before you realize it in a "closed system pond" that the KH is out of stock and there is no residual KH left in the system to prop everything up. I watch the KH numbers MORE than the PH really to be honest.
why?....
Simply put by increasing the sensitivity of the drop test you can be more than accurate enough and probably more reliable than an out calibration / poor quality PH probe. Plus it is KH that prevents a PH slide (read the word crash) so if you maintain a stable KH then the rest is easy. I have found that a certain PH (eg 7) does not nessesarily mean you will have an acceptable KH value in the pond. In my pond for example if i let the KH drop under 2 then it all becomes very unstable and i get larger daily swings. Now not a huge problem IF you are there to react and stay on top of it but if you work long hours / shifts / go on holiday etc not so easy to control. So for this reason i err on the side of caution these days.
One other thing i found is that if my GH level was considerably higher than my KH (say double) when i got down low with the numbers this increased the swings. I do not know why this is the case as no-one has ever explained it to me. So i now set my KH and GH up so that they run Level (eg: KH 2 GH 2). Now i suspect that that in the perfect world i might be sacrificing something by running slightly up on the written ideals but its the best way for me to do it.
The rules you see are quite hard to quantify i think, whereby you see - change "X" % of water, have a TDS of this reading, have a KH of this level etc etc. EVERY SINGLE POND IS DIFFERENT - and it is ultimatly the pond and it inhabitants that effects the water. Find the comfort zone for your pond and go there - now this may be easier for me to do as i came from a bad place:-
PH 8+
KH 11
GH 16
TDS 440+
So for me to accept
PH 7.1 - 7.3
KH 2
GH 2
TDS around 100 - 150
is easy as it is a million miles better than where i was and the results show that. It is a lot harder to accept it if your trying to improve water of say PH 7.6 - 7.8 as the changes are minimal and you'd need a good eye to spot the difference.
Be interested to hear what you decided with this and how you reacted to the scenario. Sorry to drag the thread back up but i was on holiday when you posted it and i'm now playing catch up.
Re: Water Utopia
Greg,
Thanks for bringing this thread back up to the top, I had hoped it would be a long discussion with all the RO users I know on this board adding their experience and Knowledge for us all to understand the science a little better. At present I have increased my mix water to bring the levels up as you had mentioned. When the Kh has become settled in the 2-3 zone then I will try to draw back on the mix, until I reach a point I am happy with. I hope to do this during the high feeding periods for obvious reasons and then just monitor the levels through the winter. I feel that if I can get it right during the summer then the system should be more stable all year round.
I feel this is the best course of action for me as I am very busy with work and maybe have to take my eye off the ball some days. I feel that I cannot trust the ph contoller route as the cheap probe systems that are commonly used are not reliable enough for me, and I feel the better quality ones may not be necessary any way.
I look forward to hearing everyones experience on this topic.
Best regards
Simon
Thanks for bringing this thread back up to the top, I had hoped it would be a long discussion with all the RO users I know on this board adding their experience and Knowledge for us all to understand the science a little better. At present I have increased my mix water to bring the levels up as you had mentioned. When the Kh has become settled in the 2-3 zone then I will try to draw back on the mix, until I reach a point I am happy with. I hope to do this during the high feeding periods for obvious reasons and then just monitor the levels through the winter. I feel that if I can get it right during the summer then the system should be more stable all year round.
I feel this is the best course of action for me as I am very busy with work and maybe have to take my eye off the ball some days. I feel that I cannot trust the ph contoller route as the cheap probe systems that are commonly used are not reliable enough for me, and I feel the better quality ones may not be necessary any way.
I look forward to hearing everyones experience on this topic.
Best regards
Simon
Re: Water Utopia
Simon,Norseman wrote:. At present I have increased my mix water to bring the levels up as you had mentioned. When the Kh has become settled in the 2-3 zone then I will try to draw back on the mix, until I reach a point I am happy with.
I think this was / is the right thing to do. Rather than trying to rescue the situation bit by bit and possibly getting in a muddle. Get to a "safe" point and begin agian. Your lucky i guess that your tap water allows you to buffer by it having a high enough KH value to do this on its own. So that it can put KH in faster than your using it (i can too) - but some people cannot due to such low KH so they need to boost using Bi-Carb all the time over multiple days. I do wonder if they turned the RO off and ran totally tap only to rescue the situation that they could.
I struggle with the suggested Mix's and the suggested water change volumes for the reason's i mentioned above in my other post.
When somebody says set up a mix of say 100ppm TDS then that's weird as how do they know how many gallons that equates to in a mix for your supply and how do they know the usage rate of KH in your pond based upon stocking levels / feed rates etc. Much better to target readings in the pond (especially KH) as the desired level of manageability.
Its the same with mix ratios eg;- 70% RO 30% tap - sure even if they know the RO unit your using then how do they know this will give you the required amount of water for your pond? Ultimately i think maybe as we begin a journey into RO it is much better to be "safe" with your readings and allow for miss calibration etc.
Probes and PH controllers - i am going this route but will be using them as part of the overall testing package rather than the sole means of knowing my water. I think the tough environment that these probes have to survive in means we as koi keepers need multiples of these and regular strict cleaning / storage / calibration regimes. Using them as part of the three way testing system and sticking to good practice too can result in readings you can trust.
Its quite a common thing to get into the "mind melt" of not trusting your equipment but providing you do what is needed there is IMO no reason why it should fail you. Plus it always pays to have a back up just in case. Nothing worse then a probe breaking and then you not being able to get parts to get it running again - this i think then leads to "its been OK for "X" weeks so i get a new probe next month - blah blah blah" - then trouble is bound to hit you.
If your interested i will talk a bit about my testing etc and frequency but rushing before a night shift at the minute. Plus be good to get Syd's feedback on my protocols as i know he specialize's in that kinda stuff.
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Manky Sanke
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Re: Water Utopia
Greg,
That's good advice you gave to Simon about getting the water right first before you start trying to control it. With some of the more complex water chemistry systems I've installed or maintained its my usual starting point - manually fix the water with all the controls turned off and then set the controls to maintain those parameters.
I agree with what you say about achieving a 100 mg/L TDS or any other particular value. I'm often asked "what should my TDS be?" Very briefly, without all the explanation that goes with it, my answer boils down to "get the water correct - read the TDS - that's your number". Because, as soon as you start feeding the bugs in a bio-filter, (using some koi as convenient middle-men to turn pellets into ammonia), everything changes. The bugs start using KH about seven times as quickly as the koi can produce ammonia for them.
So that may make it seem as if the simple answer to KH would be just to throw in one handlful of food and seven handfuls of carbonate, but such a simple calculation doesn't work. Firstly only (typically) 40% of the food is protein that can eventually become ammonia. Then (approximate ball-park figure) two thirds of that protein stays inside the fish as growth and the energy they need to live. That only leaves one third of the possible ammonia available to be excreted.
So one handful of food plus 0.9 handfuls of pure carbonate (7 reduced by 40% then reduced by 33% equals 0.9), that will do it, won't it? Nope, that's far too simple. Bugs reproduce and then they die. Otherwise we'd be over-run with them. As they die, they decompose and release back into the water, the carbonate they "ate" during their lifetime which provides another source of carbonate for their descendents.
After that, it starts to get really complicated....
Aiming for a particular KH or TDS and trying to achieve that by predicting a particular mix of water is almost impossible, so "suck it and see then tweak it accordingly" in my opinion is the best approach.
There is no point using any kind of meter or controller that you don't feel able to trust but it's sensible to bear in mind their shortcomings or possible reasons why the readings may become in accurate so I like the idea of using probes as part of the data rather than relying entirely on them. pH probes work on the principle that a liquid outside the glass probe can interfere with the gooey stuff inside it via a semi-permeable membrane and this produces a voltage which is dependent on the pH and which can be measured. This voltage is turned into a display to represent the pH but the gooey stuff ages and alters the output voltage so for a probe to be trustworthy, you have to keep them accurate by regular calibration and cleaning. Apart from the electrolyte aging, one of the greatest problems with using a pH probe to measure pH is to get the liquid in close enough contact to the probe to allow it to transfer hydrogen ions. If the surface of a probe becomes contaminated, this process is altered which makes the reading inaccurate and it must be cleaned. Protein, in particular is something that is in a pond and will combine with silver from the electrolyte (gooey stuff) and which will clog the membrane.
Regular calibration is the best way to find out if the probe has become inaccurate. If it can be cleaned and successfully recalibrated, it can be re-used. If not, it can be discarded. Having a spare probe is a very good idea because the dosing system will be working again well inside an hour as opposed to it being out of action until a replacement is obtained.
That's good advice you gave to Simon about getting the water right first before you start trying to control it. With some of the more complex water chemistry systems I've installed or maintained its my usual starting point - manually fix the water with all the controls turned off and then set the controls to maintain those parameters.
I agree with what you say about achieving a 100 mg/L TDS or any other particular value. I'm often asked "what should my TDS be?" Very briefly, without all the explanation that goes with it, my answer boils down to "get the water correct - read the TDS - that's your number". Because, as soon as you start feeding the bugs in a bio-filter, (using some koi as convenient middle-men to turn pellets into ammonia), everything changes. The bugs start using KH about seven times as quickly as the koi can produce ammonia for them.
So that may make it seem as if the simple answer to KH would be just to throw in one handlful of food and seven handfuls of carbonate, but such a simple calculation doesn't work. Firstly only (typically) 40% of the food is protein that can eventually become ammonia. Then (approximate ball-park figure) two thirds of that protein stays inside the fish as growth and the energy they need to live. That only leaves one third of the possible ammonia available to be excreted.
So one handful of food plus 0.9 handfuls of pure carbonate (7 reduced by 40% then reduced by 33% equals 0.9), that will do it, won't it? Nope, that's far too simple. Bugs reproduce and then they die. Otherwise we'd be over-run with them. As they die, they decompose and release back into the water, the carbonate they "ate" during their lifetime which provides another source of carbonate for their descendents.
After that, it starts to get really complicated....
Aiming for a particular KH or TDS and trying to achieve that by predicting a particular mix of water is almost impossible, so "suck it and see then tweak it accordingly" in my opinion is the best approach.
There is no point using any kind of meter or controller that you don't feel able to trust but it's sensible to bear in mind their shortcomings or possible reasons why the readings may become in accurate so I like the idea of using probes as part of the data rather than relying entirely on them. pH probes work on the principle that a liquid outside the glass probe can interfere with the gooey stuff inside it via a semi-permeable membrane and this produces a voltage which is dependent on the pH and which can be measured. This voltage is turned into a display to represent the pH but the gooey stuff ages and alters the output voltage so for a probe to be trustworthy, you have to keep them accurate by regular calibration and cleaning. Apart from the electrolyte aging, one of the greatest problems with using a pH probe to measure pH is to get the liquid in close enough contact to the probe to allow it to transfer hydrogen ions. If the surface of a probe becomes contaminated, this process is altered which makes the reading inaccurate and it must be cleaned. Protein, in particular is something that is in a pond and will combine with silver from the electrolyte (gooey stuff) and which will clog the membrane.
Regular calibration is the best way to find out if the probe has become inaccurate. If it can be cleaned and successfully recalibrated, it can be re-used. If not, it can be discarded. Having a spare probe is a very good idea because the dosing system will be working again well inside an hour as opposed to it being out of action until a replacement is obtained.