# What's a good TDS reading for RO water?



## Gizmo (Dec 6, 2010)

The TDS of my RO water is 43 ppm. Is this a decent reading for RO, or should I look into new cartridges? Thanks!


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## jrman83 (Jul 9, 2010)

What is the TDS of your tap? Keep in mind that if anything is in the bucket your water is going to, and I mean anything, the TDS will go up.


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## fishguy2727 (Sep 5, 2011)

0 is ideal. IME you usually need to run DI as well to really get it down to 0. 

Many times only one stage needs to be replaced, like the prefilter. 

Try to get a sample as it is produced, not sitting in the container. that way you know exactly what the water is being produced at.


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## sivakv (Aug 6, 2010)

the fishes need some salts, 43 is soft water. you could google and find out the fishes you have and TDS range it requires.


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## fishguy2727 (Sep 5, 2011)

I didn't realize all the OP's tanks are FW. 

Why are you using RO water? 
What are you adding to it?


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## Gizmo (Dec 6, 2010)

fishguy2727 said:


> I didn't realize all the OP's tanks are FW.
> 
> Why are you using RO water?
> What are you adding to it?


I have very hard water where I live (GH = 11 deg, KH = 10 deg). I use RO to lower the hardness and lower the pH. I add back in SeaChem equilibrium to get a GH of 5 deg, SeaChem Alkaline Buffer for a KH of 5 degrees and a pH of 7.4, and some dry chem fertz and iron supplements for my plants. I'm intending to have south american cichlids like GBR's and some tetras and through research I've found they like soft water with low pH.

Plus I use the unit for water for ironing 

I'll test the tap water and fresh out of the RO unit when I get home tonight.


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## fishguy2727 (Sep 5, 2011)

Were you having problems before you used RO?
-If not then I would not change things.

High water quality and stability is more important than specific hardness/pH. Discus can breed in 7.6 water, they don't need it 4.5 (or 6.5). 

I would NOT use 100% RO in your situation. You would save some money by using half tap half RO. This does exactly what you want (reducing GH, KH, pH, TDS, etc.) but do it much more safely. It uses the natural chemistry of the tap water, just dilutes it. This is safer than starting from 0 and trying to work your way back up and hope it is stable.


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