Continuous Drip System - Help me out

Hey everybody, this is my first thread in rollitup.org, although I have been around as a member for well over a couple years now. My friend has a sweet continuous drip system, and his roots are constantly under the water, as he has no way to flood the tub. What is a recommended method to solve the over-watering problem? He does have one air stone which pumps a constant supply of fresh oxygen into the water at both ends of his 4'x3' table (Big pump with two hoses to disperse the oxygen). He knows of the recommendation to allow the roots to hang and flood the system a few times daily, however this is not an option. Is the best bet for my friend in particular, to simply install a second air stone to provide even more oxygen to the roots, or should he look at a CO2 pump even?

Current conditions of his hydro system: He only ever has 10 out of the 40 possible plants because he is medicinal and doesn't see a purpose to so many plants. He has a two plant harvest every two weeks, however his plants are really bushy and thick due to the over-watering. The plants to make it through every stage successfully, however he was curious as to why the leaves were so wide and thick.

Thanks Rollitup, you always know what's best =D

you guys need to do some reading I think. Anyway, if the roots are always in water then ou shud put a airstone in them but if they are not showing overwater signs then it is more of a fact thing. If it is dripping into a bucket like I imagine then why not drain the buckets. Like a hole in the bottome and let it spill into a hose leading intot the res or onto a flood table. Are these prebought store systems? I dont think big leaves mean over water. I think they mean a lot of blue light, indica, and N is good. Big leaves are not a prob. Too much green might be but I dont think that is yur prob. Over water looks like droopy and yellow leaves.

My next question is:

My friend showed me his crop again today, and it appears that one of the plants was beginning to get a few spots of light green/yellow which are appearing on the fan leaves of only one plant in the hydroponics system, and like I said, only a few small spots, about the size of a water droplet are present, and the leaves do not appear damaged, however it appears that they were coming close to it? I have been doing some reading and figure that this is probably the result of the strain being sensitive to fish products, however I cannot come to my own conclusion, does anybody have any input as to what it might be?
Thank!