your lucky any strain is doing alright. SOFT WATER FROM TAP is your problem if all else is good as your info.

What do you mean by soft water from tap ? If it's a water softener then it's ton of salt ! If it's municiple water then it loads of chloramine a solid frm of chorine that does not evaorate when left out. think about drinking that.

Get some distilled or reverse osmosis water and start clean. Only put what you want and your plants need back
I'm kind of hung up on ( How much poisin is too much )
If you need a good R/O filter let me know, I searched till I found a good portable that wasn't way too much for what it gives.