My rule of thumb for starters/average is 1gph per 100gal… depending on stocks ive done as much as 3-4gph per 100gal as well. Current tanks are 450g at 4gph, 500g at 6gph, 230g at 2gph, and 650g at 4gph.. just keep testing ur water until u get the nitrate levels u see fit. I keep mine under 5ppm. If ur just guessing. Run ur drip into a 5gal bucket and time it to get an idea. Highly recommend using pressure regulated emitters and also a pressure gauge to monitor the psi in ur drip lines.