Thanks salvein

Yes! Ph down is what I meant

I too think the ppm is high, But ph isn't low ? Also not seeing any Signs of burning. Also something im not sure about is that my ppm hasn't moved since I cleaned and refilled Rez. Water has gome down and topped off but ppms been at 740 all week?

Hmm, yes when I add my ph - ive just been sliding the lid over and adjusting like that, not good? Also it seems the air bubbles makes my ppm meter jump around a bit so I hold it off to the side of bucket to get readings.

My ambient temp is about 70 but is a bit cooler at night.
For lights I'm using an 8 bulb t5 fixture.