I don't think drip rates are that critical. As long as water drips out the bottom that tells you that the medium is saturated and the T&E (transpiration and evaporation) rate is not affected.

The one thing to consider is whether the roots are getting adequate oxygen. A lot depends on the density of the medium. A densely packed medium like vermiculite will have a harder time getting oxygen to the roots than say clay aggregate.

A lot of growers use timers with their drip system because as the water drips out the bottom of the pot air get pulled in (to replace the water volume lost) during the "off" cycle.

Good info, thanks Hank. I am using Hydrotons, and the water is free falling from trays back to catch basin, so I am thinking that I will have no problem with oxygen.

What types of plastic tubing are people using for their systems? I bought a flexible PVC pipe, but it is not flexible enough for my liking. Thinking the dishwasher type lines would work better.

I use a 0.25-0.5 gpm/plant pump, but that's because that's what the store had.

I have experimented with cycling the pump from 15 sec on 1 hr off and everywhere in between.

I now run the pump when the lights are on (16 hr/day) because the timing didn't make any difference I could measure.

Use black or completely opaque piping. I use rigid plastic for the nutrient supply and drainage because my grow space is dedicated to growing and the configuration doesn't change.

Use piping with smooth interior or nasties will get caught on the inside of the piping where you can't see......

Willard is right about the opaque piping. I used transparent tubing for a while till the algae started coating the insides. Now I use 1/2 in. black irrigation tubing which is semi-flexible.

Drop a simple ceramic airstone fed by a cheap aquarium pump to your resevoir. The DO or dissolved oxygen it creates will boost your growth rates and help compensate for the continuous flow. I have had better luck using the smaller stones also Let me say that I did not believe it at first.....now I do...it really really helps.

I made a drip system with a 130 gph pump in a 18 gallon tote, feeding up to another 18 gal tote with the plants and just dripping back down. I'm doing it outside running 24/7.

Should I put in an airstone in the resevior? Also, all my plants were started in jiffy peat discs, and I put the whole peat disc in with the hydro pellets, I assume this is correct, the peat is saturated and the runnoff drips down.