# RO/DI Waste Water



## mheltcameron (Aug 1, 2012)

So I have a 14g Nano Reef. I have a 5 stage RODI system to produce pure water for my reef tank. I have read many people who said they have luck using the waste water in their fresh water tanks. I am making three buckets of waste to every one bucket of RODI which is perfect if I can use the waste in my 55g fresh. I tested the waste before using it and found:

Nitrates-0
Nitrites-.25
Ammonia-.30

In a 15g water change to a 55g tank every two weeks will this trigger a cycle? Thanks


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## dreday (Oct 12, 2007)

You do not want to use the waste water for your tank. That is an old wives tale.

If you have a high ph the nitrite and ammo will harm your fish. It could even kill them over time. I would stick with what you were doing before, tap water. All the heavy metals will be in your waste water as well, that is not good for the fish.


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## Chromedome52 (Jul 25, 2009)

It is not waste water unless you waste it. Under most conditions, the byflow water from an RO system is perfectly safe, just slightly harder than your tap. I don't know why you are getting such high measurements on nitrites and ammonia, as that suggests that they are already in your tap water, which it shouldn't have to begin with. In a multistage RO system the heavy metals should be removed by prefilters, as they can damage the membrane and shorten its life. But a lot of people forget to change out the prefilters regularly.

I've used RO byflow water for many of my livebearers and hard water fish for years with no problems, the plants love it. I would check the levels of nitrites and ammonia in your tap water, I suspect they are not much lower than your byflow water. And a 15 gallon change every two weeks in a 55 isn't enough water changing anyway, unless you have a very lightly stocked tank.


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## mheltcameron (Aug 1, 2012)

I agree that calling it waste water is a bit of a miscategorization. It is only a concentrated form of the RO water, it has already been filter through a sediment filter and 2 carbon filters. My TDS out of the RO is only 1ppm million, when I am flushing the filter the TDS maxes out 60ppm, so it would seem that I have great water from the tap. That being said, after testing the "waste" water I pulled out a bucket of my RODI to make sure there wasn't something going on with the system and that water was zeros across the board. I will have to test the straight tap. The "waste" water had been in a sealed bucket for 3 days. Just for the **** of it tossed half a cap of prime in the bucket I will test again tonight and see what I get. I would rather continue using the prime as I would out of the tap, was hoping I would be able to eliminate that step, and not send 15 gallons down the drain for no good reason.

At the moment I have one Jack Dempsy, big guy though, 8" or so and a Peppermint Pleco, about 3". Two weeks is the max that I go, have a pretty good balance in the tank. Pleco does a pretty effiecient job of cleaning up what the jack doesn't eat. I check my parameters in the tank weekly, and if they aren't to high I let it go in to the second.


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## mheltcameron (Aug 1, 2012)

So I tested the "waste" water after treating with prime yesterday, nitrites down to 0 and ammonia down slightly below .25. I tested my tap water and got an Ammonia reading of .5. I have been using conditioned tap water since I started the tank 6 months ago ad haven't had an ammonia reading on a water test since the cycle was completed, so it would that the "waste is actually better than the tap water in that respect. Thanks for the responses.


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