I always overdose a little, in my 125, I throw in a full tsp.
In a 75 gallon tank, 1/2 tsp
In a 20 1/4 tsp
In a 5 gal, I just shake off a 1/4 tsp until I think its enough.
When I notice ammonia, throw in 4x the dose.
Just make sure you have enough aeration going when you really overdose.
IBC and Shelve Aquaponics
Show your aquaponics
125g Breeding group Tilapia
2x 75g+ 40B Tilapia outgrow tanks
20H Philippine blue Angelfish breeders + fry
20L CPD and Shrimp tank
10g Apisto Gibbiceps
Savannah Cat: Kimchee