Originally Posted by BBradbury
You can't overdose this water treatment, so you don't have to get the dose down to "the gnat's butt".
I use approximately half a capful in a five gallon bucket of tap water and let the bucket stand uncovered for about 15 to 20 minutes and then syphon the water into the tank.
My fish and plants have never complained.
You can overdose almost anything, Prime included. The bottle states safe up to 5x and the Seachem reps I've talked to say it is probably safe to twice that, but overdoing anything is usually bad. More is better leads to a lot of problems.
The best bet is to dose as directed, which is 1ml / 10g.