Recycling old aquarium water for Phytoplankton Culture

[Jon Lazar]

I use the RO/DI waste water both for phyto and FO top off. I agree that the tap water contaminants are concentrated some. I think my RO/DI discards 4 units of waste water for every 1 unit of RO, so my contaminant level is 20% greater than straight tap water. I don't exactly what crud is in the tap water or at what levels to begin with though, nor do I know what levels the fish are sensitive to each contaminant, if at all. From the posts above, it looks like several folks have good results with dechlorinated tap water, from different water sources.

The concentration is a good point though, and I'll keep it in mind.

Happy reefing,
Jon

<a href=showthread.php?s=&postid=8467103#post8467103 target=_blank>Originally posted</a> by Kathy55g
please clarify whether you are talking about culturing phyto in this water, or giving this water to your fish tanks. The reject water is concentrated in nitrates and other pollutants the RO takes out. I would think it is unsuitable for fish.

 

[GreshamH]

<a href=showthread.php?s=&postid=8467103#post8467103 target=_blank>Originally posted</a> by Kathy55g
please clarify whether you are talking about culturing phyto in this water, or giving this water to your fish tanks. The reject water is concentrated in nitrates and other pollutants the RO takes out. I would think it is unsuitable for fish.

Not as much as you'd think. The waste still passes thru the carbon and prefilter

 

[Kathy55g]

Agreed, but I once measured nitrates in my RO reject water--high off the scale. Nitrates will accumulate all by themselves in our heavily fed concentrated fish systems. No need to supplement. And RO is supposed to remove pesticide residues, and other larger molecule hazards. If you use the RO reject, you are getting all those things in a more concentrated form. In my opinion, it is better to just use tap water that is carbon and sediment filtered, but not the RO reject.