Using RO water?

[jamjarjames]

Hi

We have had an RO system installed in the kitchen. I would like to use this in my tank which will contain Cardinals, Oto's and Rams. Is there anything i need to treat the water with before i put it in the tank, ive tested the ph of it and it came out at about 6.7 so should be ok in that respect. Im going to dose my plants with fertalisers and im using a flourite substrate so the plants should be ok. Just whether the fish need anything else in the water?

Thanks

 

[anonapersona]

mix back some tap

You will probably need to mix back some tap water to get the KH you need to keep the waer stable. Pure RO has 0 KH and so there is no buffer to keep the pH level, you will get pH crash easily.

Plants also require the calcium and magnesium you are removing with the RO.

Personally, I would use mostly tap water, then mix in some portion of RO to get the KH at 3 to 4. I don't know if that will be 20% RO or 80% RO, you will have to test the tap water to know how to mix.

 

[OrionGirl]

What's the KH? This will determine the stability of that pH. It's likely pretty low, so you'll want to mix the RO with tapwater for the buffer.

 

[jamjarjames]

Im not sure what RO tests out for KH but i know the water round here has a very high KH. Is there anything else that can raise the KH of the water, did i hear crushed coral works?

 

[OrionGirl]

It does, but mixing with tapwater would be easier and more reliable. RO filters remove the carbonate buffer, so even starting with high KH water, the RO filtered water will likely be too low. It will also mean that the RO filter membranes will need to be replaced more often.

 

[jamjarjames]

What KH value should i be aiming for when i mix the water?

 

[anonapersona]

KH = 3 to 4 degrees ( something like 60 to 80 ppm if I recall correctly the factor)