IMHO the air curtains are alot better than the stones for DWCs. i used the 6" and 12" blue air stones from walmart and after a while (a few months) they stopped up so much that the bubbles where huge and just coming out of 1 end of the stone. with the curtains ive never had any probs with them stopping up at all. they put out mostly small bubbles, and can be cut to fit just about any res.
also,,, i had a 20 gallon bubbler with 6 plants when i first started growing hydro. at first i used 2x24" air stones. then i used 4x24" cuz i thought more was better. the tote with 4 stones didnt do any better at all than the tote with 2. when it comes to air stones, i think its more about placement than anything else. as long as you have enough stones that the bubbles get up into the root system your gold. i also noticed a huge jump in growth when i dropped my res temp from 80 to 65. cooler water holds much more o2.
now i use just 4x24" air curtains per 50 gallon DWC. and 2 of the pumps exactly like your useing. i had 6x24"air curtains with 3 pumps, but didnt really see that it did any good. hope this helps
