..yes, heat too high(pushing it!)---ventable lights? <---You need to get the heat from the lights out of there.......
The Masters on here say to keep your pH @5.8.....you really dont want it over 6!
What's the temp in your res??
What size rw are you using?<----will determine watering frequency....... I would think if you keep the rw above your flood level you could water more times----you just dont want it(rw) too wet.
Nutes??? Yes...... are you following their schedule??? PPM??
As your plants grow they'll use up more and more water/nute......you may very well need to 'top-off' hith h2o and I dont think you add nutes until res change---research that or maybe someone will chime in.
I am new to hydro myself and I wish you luck!! Soil was so much more forgiving but this grwth rate is unreal!!
growinman