I've only used Sweet twice. The last time was yesterday morning at 1/4 recommended dosage.

I always let my plants dry before watering, the exception being when I was finally able to afford nutes and over-watered and over-ferted.

Seedlings should never dry all the way out, but I do wait until the top of the soil is dry about 1/4-1/2" down. Seedling soil is light and fluffy, and I find that when it starts to dry, it dries out very quickly. I had just watered the seedlings before I noticed the little brown spots. That's when I took the picture. Did you look at the large-large view of the seedling close-ups? See those little brown spots? And see those dark-purple stems? I have NOT used any nutes, sprays, etc..

The ONLY common element between the two crops (the flowering crop & the seedling crop) is the water. There must be something in the water...or not in the water. I do not use hot water from the water heater. No crusties on my faucets. We drink it everyday.

I can't afford an RO system or an official water test, and my pH seems to be OK. It measures only 75ppm on average with the TDS pen. The average tap water in the US is 200-400ppm with "hard" water beginning at 200ppm so I??d like to think 75 ain??t bad. How else can I check my water?