Confused with GFO and Alk...

lyrical · Mar 10, 2015

So I have never used GFO before and read all over how great it was and also read how it can lower the Alk. What am I missing? How is GFO so great if it creates a low Alk problem? What is the best way to address that?

TIA

Randy Holmes-Farley · Mar 10, 2015

It doesn't cause any problem if you monitor calcium and alkalinity, as you should anyway.

What happens is that the iron in and released from GFO can cause some precipitation of calcium carbonate on and just downstream of the GFO.

So in that sense it is just like having some additional corals.

lyrical · Mar 10, 2015

Thanks Randy.. that kinda makes sense lol. I would assume then by your explanation that adding GFO slowly to the system would be a good idea just like you would not want to add a ton of fish or corals at one time?

Randy Holmes-Farley · Mar 10, 2015

The concern about using too much is usually from a phosphate perspective, not alk. The alk effect is usually fairly small and is not especially rapid.