RO system query - mechanical

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chita
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Post by chita »

I just hate to see parallel trials, the time can be put to better use!

Chi
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Gazza
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Post by Gazza »

Just goes to show we have nothing better to do than test lol :lol:

If it makes my fish feel better then i am all for it,just need to save up and stop buying testers and get some decent koi :lol: :wink:
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chita
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Post by chita »

I work around 20 hours a week over 52 weeks these days, so I have a lot of time and resources with which to prove or disprove theories and ideas, mine and all the rest!

Chi
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Post by Gazza »

Yes sounds a bit like me but unfortunately i have been a bit busy :cry: :cry: :cry: :cry: never mind it will soon be 2006 :lol:
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Post by B.Scott »

Saw this on ebay. I figure I could leave the last carbon filter out and use it as a replacement for the first one.

[url]http://cgi.ebay.nl/ws/eBayISAPI.dll?ViewIte ... Track=true[/url]
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Post by Gazza »

Hi Scott,

Not sure how that would perform you may be better off looking at this site:

http://www.ro-man.com/shop/product_info.php ... 4/cPath/22
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Post by B.Scott »

Thing is this one has a pump and my mains pressue is only 2,5 bar
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Post by poey »

hi all
this may seem like a silly question,but once you have lowered the tds to the disired levels.how do you restrict the flow from the r/o on the pumped system so you can tailor the water changes to keep the disired tds levels?
do you always have to use the full output from the r/o on a overflow to waste system?
cheers Dave.
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chita
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Post by chita »

Hi Dave, there are a number of methods for ongoing control, I'll cover a couple and you can invent your own to add to the list of options devised by users. Hopefully others will put in their favourites, but the question is not as straight forward as it sounds, due to the huge differences possible in pond design and operations.

You could simply turn off the pump and use mains pressure only, which of course reduces output hugely.

You could exchange the restrictor for a different value, increasing waste and proportionately reducing product, not my favourite.

You might increase the untreated water trickle flow to balance the input water.

You could rely on the fact the RO membranes will gradually clog, reducing the flow automatically.

There are numerous options, including fitting a timer to control production.

My own system has not given me problems in this respect, so I'll explain.
I have a 125 gallon storage tank for RO water. The output from the RO stage is "Teed" off, one feed going to the storage tank via a float, which normally shuts off the pump pressure switch when full. However, in my system the flow you'll remember is split, so when the float shuts off the flow to the tank the flow to the pond doubles. But, I have a small ball valve in each of the two flow lines, so if I wish I could simply reduce the flow, but I don't have to. Because, when the tank is full it's time to flush one of the filters, and I need the stored water from the tank to go into the refill mix, and the process starts all over again.

Obviously I have a pond overflow in place and my normal practice includes trickling a 4 to 1 ish mix of RO and mains water to the pond 24/7. This equates to about 100 gpd into a max 2000 gallon pond, which I figure is about perfect. I set up the two trickle lines for RO and mains water to produce a mix of water at KH2 to 3.

The problem is that for speed it's better to have a large volume production unit for RO when setting up, but subsequently a smaller unit is fine! It usually means that with the correct unit for ongoing use it takes 3 to 5 weeks to bring the water into the range we require, no real hardship as it gives the koi a chance to adjust.

I hope this provides a few ideas, and confirms your hopes that you're not missing something obvious!

Chi
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Post by B.Scott »

Chi, I was thinking (uh oh, dangerous!)
I have a new RO unit I have yet to install. It came with a 50 gpd membrane and I bought a 100 gpd membrane to replace that with. Now if I was to piggyback the 50 gdp on top of the 100 gpd, split the feed and put a valve in front of each membrane, I could choose between 50, 100,or 150 gpd simply by opening and closing a valve. Would this hurt the membrane not being used? I would think not as long as it was kept submerged and I would be back washing it weekly (or more often should I think of it) so the water wouldn't go stale.
This system would allow me to regulate the flow to some degree. I would love to be able to store some water for when I flush the filter. I have a great 50 gallon barrel to do it with but no place to put it. The wife gets silly and tells me I can't put it in the kitchen or the bedroom. (why do the ladies always act so difficult?)
Does this sound like a good idea to you?
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chita
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Post by chita »

Hi, the idea is sound, offering a simple solution for variable and increased output. If you want to get the best recovery / production rates with the minimum waste water, running the two membranes in series is ideal, as this recovers a higher percentage relative to input.

RO membranes are very difficult to dry once wet, so the risk from dissuse is bacterial growth within the membrane. This is not going to cause problems for a few days at a time, but might in a few weeks. There is less risk if they are kept full of water, but if long term dissuse is likely they should be removed and stored in a 1-2% solution of sodium metabisulfite.


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Post by poey »

hi chi
many thanks for the info,shortly i will be getting one of the r/o units like yourself and gazza are using.
at first i will be imputing r/o water alone to dilute the pond water to the desired levels,then when it comes to the r/o,tap water mix in theory i think a 3 to 1 mix should get me the desired water,kh2,gh3.
as I'm on a water meter if i find i do not need to change the full output of the r/o unit/tap water mix daily is it simply a case of putting a valve on the r/o unit output line to reduce the flow?or does this put back pressure on the units membranes?
then adjust the tap water to still give the 3 to 1 mix.
cheers Dave.
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chita
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Post by chita »

Once you reach the desired levels there is no requirement to feed a water mix daily, though some circumstances can dictate otherwise.

In my case for example I travel extensively, spending an average of 5 months per annum in Southern Europe. As I like to keep the PH at 7.0 ish, (7.2 ish in the winter) I prefer to have sufficient daily mineral replenishment as to guarantee KH stability. I choose to trickle feed to achieve that balance, but there are alternatives, especially when a pond is under supervision all year.

For example, there's no problem simply getting down to the required levels and then storing RO water in sufficient quantities to allow topping up with the correct mix after flushing. This works fine, I tested that system for 3 months before going the trickle route, no problems whatsoever. This of course saves a considerable amount of water for those on meters or with a hyperactive conscience.

I've not tried choking the RO output alone, in my system if I did this the flow to the storage tank assuming it wasn't full would simply increase. You'd need a lot bigger RO system to do more than provide adequate production to accomodate requirements for the average pond, under either of the prescriptions offered.

Chi
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Post by poey »

hi chi
thanks for the advice.
with my pond i have bakki showers as the main filtration fed from the b/drains so i have no settlement to flush.
i do have a 24"vortex on the skimmer line that i fluidized and flush daily,this uses about 50gals,at the min when i have flushed the static k the pond runs as normal and i run in water on a slow trickle to waste when the 50 gals is replaced the rest goes down the pond overflow.
at the min i change around 100gals a day using this system to maintain the tds close to the tds of the source water(250ish).
so i have to use the trickle to waste system for water exchange,i have no problem running the full production from the r/o then adding the correct amount of tap water to maintain the KH,the reason i was asking about restricting the output from the R/O unit is i see no point in changing 350gals a day if i can maintain the same water perms with 200 if you see my point.
cheers Dave.
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Post by chita »

Dave, trust me when I tell you you will not get 350 gallons per day from the system, or from many systems in fact.

This system states 300 gpd, unfortunately these are US gallons. So in the real world abot 240 gpd, as Americans like to have larger amounts of everything they reduce the amount of water in a gallon so they have more gallons!

Then there's the pressure thing, all quoted figures are at something like 110psi, which you are not going to get even pumped, so we are down to around 200 gpd now. And then there's the temperature thing, all specs are quoted at 25c, which is about double the annual average of mains water at best, so that'll be about 165 gpd then! And that's with the best possible cartridges and the best possible membranes and a reasonable tapwater quality, so in most cases 150 gpd is more realistic. But only if you really look after the system or it will rapidly drop to 120 gpd or less.

This is not a critiscism of the system, I do not believe there is a better one available for anything like the price. It's just a fact of life with RO systems, which if you don't know and your supplier doesn't know or care, will result in confusion and despair, as it has for many new users.

The system if maintained correctly is adequate for most hobby ponds, as after target water is achieved much less water is required anyway. If you were to store say 50 gallons per day this would suffice for your top up's, you would not need to continue adding 100 gpd to keep TDS down of course.

I would simply get a storage vessel and fit the float valve kit obtainable from the same source, this will shut off the pump when the tank is full as the pump unit has an integrated pressure switch and flow valve / sensor.

The membranes can be prevented from drying out by adding none return valves in the lines, these are obtainable in the simple push in fittings for a few pounds each, again at the same source.

Of course if you are not metered the trickle flow system is fine.

Chi
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