Advice on using RO

[Weird Fish]

Hi,

I have been hanging around the forum for a while now, having gathererd some very good info from the forum i have decided to go down th RO route. It was a visit to Mike at Yume Koi that swung it!

I have set up the Ro unit 3 stage purifier through 3 x 100gpd membranes in series as i'm on a water meter.
Tap water is :-
TDS 312ppm
KH 14dKH
GH 19dKH
PH 7.5

This is really anoying because before the hose pipe ban up here in the North West i had TDS 52ppm, KH 2dKH ,GH 4dKH & PH 7.3 out of the tap, Water board must have switched suppliers at some point.

RO water :-
TDS 12ppm
RO 130gpd
Waste water 110gpd

Pond water reading are as followed :-
TDS 532ppm
KH 6dKH
GH 13dKH
PH 7.9
Temp 20c

My question is do i just run RO into the pond until i reach my required TDS keeping an eye on the KH, or do i mix ro with tap and bring the TDS down slower?

James

[Gazza]

Hi James,

Welcome to Koiquest

I would just run pure RO and when you get down to where you are happy with then you can either mix some water or bung in some bi carb now and then.

[Weird Fish]

Hi Gazza,

Thanks for your reply, thought this was the way to go. Its only been running for a few days but seems like 130gpd on a 4500 gallon pond is going to take forever! I'm dropping the filter twice a day to add the RO which I've got running 24/7 rather than just running the RO in and letting it overflow? Thought by removing the water it would help to lower the TDS quicker? How often is recommended for flushing the RO membrane? as I don't have an auto flush.

Cheers,

James

[greg]

James,

First up one thing i notice is that you have quiet a discrepancy between your tap water and your pond

TDS tap - 312ppm
TDS pond - 532ppm

In a well run pond (not running RO) this number should be as close together as possible. It is good to get the difference less than 100ppm and in an ideal world it wants to be less than 50ppm difference. This to me indicates that you have not been cleaning filters enough / doing enough water changes or your adding a product to the water that will boost the TDS levels. Possibly even due to your stocking levels

KH tap - 14dKH
KH pond - 6dKH

Again as above. Your filters use KH as a source for the bacteria and they use it up over a period of time. A KH that is drastically lower than the water your adding to the pond indicates that you are possibly using it up faster than your adding it and COULD crash the PH.

Now your trickling RO you should see these readings move closer together due to the increased maintenance / water trickling in and out - but you might find you have to keep a close eye on this.

Membrane flushing - as often as you can - minimum twice a day IMO if your doing it manually but much better to invest the few pounds in an autoflush kit. £30 now could save you a fortune in membranes over time!

http://www.purewaterproducts.co.uk/inde ... ucts_id=93" onclick="window.open(this.href);return false;

Hope this helps,

[Weird Fish]

Greg thanks for replying,

The differance in pond and tap TDS is more than likley due to adding around 100kg of salt to the pond at the start of last winter
due to a bacterial infection on 1 of the koi this was advised by my local dealer after anibiotics seemed to fail. TDS was 2900 really regret adding it now as iam struggling to get rid of every trace of it.
I clean the filters 3-4 times a week and top up with around 1-1.5 cubic meters each time. Stocking levels are 13 koi 12" - 26" in 4500gals. I will keep a close eye on the KH testing daily.

Thanks for the info on the autoflush kit will order 1 asap.

James

[Gazza]

Hi James,

I would get a auto flush on the system as they will help the system run much better and protect your membranes. The harder the water the more frequent you need to flush to make sure there is not build up of waste. I flush mine twice every hour as i think its best to flush regular rather than a few longer flushes and the link that Greg has given is the man to get your equipment done Alan is a top man and very helpful