Aeroponic Water/Nutrient Solution Levels?

I'm about to start up my 10 site, 45 gallon aeroponic system, but I'm unsure of where my water level should be. Should there just be enough water to cover the submersible pump? Maybe a few inches over? And also, how can I determine what size pump I need? (ex. 400 GPH? 600 GPH?)

Any advice from you experienced DIY and commercial aeroponic growers?

Does anyone have an idea?

Pump size is determined basically by the amount of sprayer heads you have. The more
heads the less pressure but I can get away with 14 on a 396gph pump using 1/2" pvc
and still getting very good droplet size. I haven't seen an exact answer on this question
but I usually just start with a fair amount and test it out, then add a couple more and test
to the point where I feel saturation is good and I'm not losing pressure.

Your water level is up to you but I would go with a good amount extra as this will make
less work for you if you're planning a weekly nute change out. I would avoid staying right
above the pump inlet unless you have a top off float valve, otherwise you could burn out
your pump if you're not careful and your water level lowers too much.

with my aero/nft setup i use about 10 gallons of water in my 27 gal tuffbox that i use for a rez. this number goes up as the plants get older....... towards the end i fill anywhere from 18-20 gal. but you want to make sure that there is always enough water to cover your sub pump. sorry i havent updated my jurnal or started a new one but i should do that tonight maybe if i have time. as far as pump size i use an 800gph to spray 12 plants using 1/2 pvc ans sprayers... one sprayer per plant