min/max air in the res?

RIU my question is, can there be to little or to much air in the res running a dwc setup? What is the rule of thumb as for liters of air per gallon? I'm running a 7.8 liter per min pump now but don't think it is enough for my res... at about 12 gal I have some roots coming out the bottom of the net pot that are about as thick as a pencil... I do have a ph issue res doesn't stabilize continues to drift low so I have some issues showing up on so leaves but still wondering if I don't have enough air.

I do at least 1 watt per gallon, you can never have to much air IMO. Your roots sound like they are doing real well

You can run a screw in your airline instead of airstone turn screw for adjustment-I was told.
I bought round airstone put out a lot more air.
I bet you run a gap between net pot & water.
I used to 'till I read Heath robinson say it would cause a thick roots called(I forget) that would slow growth.
I tried it & no more cord roots growth did speed up (he had more suggestions) greatly.
Just thought I would pass that along.