Question regarding taking system offlime

[demariners]

Hello, I am wondering how long can my fish be ok with just powerheads on a FOWLR? I am redoing all my plumbing and will only have powerheads going.

Furthermore. Does anyone know how long I need to wait for PVC cement before running the tank water through it? Don't want to poison any fish

 

[sick1166]

Depending on amount of water and amount of fish but I have run weeks with that set up
Pvc glue I have done in 15 min but I usually go about 30 minutes