Not sure what a PPM meter does. Im new sorry.

yes I have 2 reserviors holding up to 10 gals.

as far as the tubes go its whats is feeding the water up to the plants at the moment, should they be running 24/7 till the roots hit the water? or am I over watering?
G-M-B?? im assuming thats nutes?

So flushing tomarrow for 24hours and moving the lights up.

still not sure on how long/much the tubes pumping water should be running.(the roots are not in the water yet)