i modified my waterfarms so they have a airstone in each one making it the same top feed/dwc bottom that you have. i've kept my top feed on the whole grow.
You water pump is connected to a timer, right? How many times it goes on during a day and for how long?
the GH waterfarm uses an airpump to pump water actually. it stays on 24/7
I see, but i have 2 pumps running in each pot... The water pump is pumping 600L/H, I think it is too much to run it 24/7 =)
not to hijack the thread but did you see a noticeable benefit from running the top feed the whole time?
do you have a pic of your setup? that pump seems way too much and will probably heat up the water alot. how many gallons/liters is your res?
i think the biggest help was adding the airstone once the roots hit the lower res. i kept the top feed on the whole time since there is a fair amount of roots in the top res too that i didn't want to dry out. i also drilled out all the holes to 3/8" making it easier for the roots to hit the lower res.
dont have pics on me, but i used exactly this build - http://www.growweedeasy.com/high-yield-bubbleponics-technique
Thats the most interesting part of this bubbleponic setup, I think whole time is not nessery at all, but have no experience yet...
if yours is like the 6 site gray tub they show, i would shut off the top feed once the roots hit the reservoir. the top feed is really just to help the roots develop when the plants are small.
I have 2... What do you think about if I turn on the water pump 30 mins and 30 mins off, rapidly?
go for it. just keep an eye on your res temps. when you start getting above 70F, you can run into issues with root rot.