Keep bringing your ph down to low 5's it will even out.

You say dimmed 1000 lights. If they are on a dimmer you are still using full power at the ballast.

I know heat is always an issue. We have a small 5000btu A/C unit that keeps lights and rez temps cool. It's a must.

OK back to watering. I would not let a system like that go for more than 2 hours without a least 15 minutes on time. Light or dark period.

If I could keep my temps down I wuld run 24/7 if there were no signs of drowning or fungus. But 15 minutes every hour or two hours is where I would go.