NotAquaMan
In Bloom
Ok this is a link applied to aquariums. It's the principles I'm saying that apply to hydro and preservation of bacteria. But should give you some insight if my thought process.
The Estimative Index of Dosing, or No Need for Test Kits
The Estimative Index - What is it? The Estimative index is a simple method to dose nutrients for any tank without test kits. In a nut shell, the aquarist doses frequently to prevent anything from running out (plant deficiency) and does large weekly water changes to prevent any build up...
barrreport.com