First Grow - LSD DWC

This update for the last week is a few days late. It was a week of many minor errors, but I don't think it's anything from which the girls can't recover. I saw some brown spots in the middle of the lower leaves and felt this was likely calcium deficiency from using distilled water. I added General Hydroponics CaliMagic and also Bio-Cozyme in the amounts specified on the bottles. This sent my PPM through the roof and I wound up with what I feel pretty confident is nutrient burn. (see pics) I've swapped out all my water now and went city water that I ran through a KDF hose carbon water filter. I then went back to just the General Hydroponics three part nutrient system. After reading that manufacturers tend to push the maximum limit with their recommended amounts, I diluted this amount too. My PPH out of the faucet, after the hose filter was about 300 and is about 850 now. I'm hoping this will correct the nutrient burn. My Mars TSL 2000 lights finally shipped, so hopefully they will be here soon and I'll swap them out for the Amazon burple light I have now. I also discovered that the Home Depot buckets I was using let a lot of light through. First, I tried to remedy this by painting them with some Plasti Dip. This still let an awful lot of light through, so I wrapped the buckets in black Gorilla tape and that solved the problem. I also think I planted my seedlings too low in the net pots. I guess it's too late to fix that without damaging the roots, but I'll know for next time. I'm brand new at this, so constructive input is always welcome.