when 2 change GFO

[goochesfish]

Do I wait until the output of the reactor is no longer reading zero phosphates before I change GFO?

 

[mutateddogbone]

i like to change mine about every 3 weeks. it also depends on how much you use at one time.

 

[fishchef]

I generally wait until the tank gets a high reading on my Hanna. Usually above .06. It generally will be above .19 in about 2 months.

 

[julie180]

Its very dependent on your phosphate levels. If you don't have to much, it could last for months, if you have a lot, it might only be weeks.

I test the tank like fishchef said and change when the phos starts to rise.