# Water Changes in CO2 inj. tanks



## t2000kw (Jul 29, 2006)

What's typical? How often? Does it vary much?


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## Rob Tetrazona (Jun 21, 2005)

I up the water changes for tanks I really care about. To me, that means 25% a week or 50% every two weeks. Variables also come into play such as tank size, bioload, etc. You kind of have to feel it out for your own situation. Water changes keep the buffer more constant (kH).


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## MatPat (Mar 22, 2004)

It really depends on your fertilization routine. CO2 injected tanks require much more fertilizers than non-CO2 tanks...the plants tend to grow about 10x faster with the addition of CO2.

The Estimative Index (EI) recommends a 50% water change weekly to basically "flush" out any excess fertilizers that are added. Not much testing of fertilizer levels is required when using EI.

The Perpetual Preservation System (PPS) goes without any water changes unless high levels of fertilizers are detected during weekly to bi-weekly testing.

I use EI in one tank and do weekly to bi-weekly 50% water changes. In the other tank (my Angelfish tank) I use a system similar to PPS and rarely change any water, just top off for evaporation. I rarely test my water anymore either but probably should start testing a bit more


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## eklikewhoa (Jul 24, 2006)

I do 50% every week


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