From nutrient burn to deficiency? help please

I have a Green Gelato I started from seed in a solo cup in pro mix HP under some t5 lighting. At day 15 she was doing awesome (see pic 1). Gave 2 mild feedings of green planet Medi One at 50% strength recommended for seedlings. Day 11 and day 14. Day 16 transplanted into 1gal pot of Pro mix HP which I had moistened with water pH’d to 6.0 transplanted and gave a recommended feeding for seedlings. And placed her in new home under HLG 320w LED light. Been downhill ever since. Within a few days she showed some pretty good nutrient burn (pic 2, day 22). From that initial feeding at transplant she has been getting just PH’d water. She recovered slowly and I removed the burnt leaves. Today (day 33) looks like this (pic3) and she looks like she needs food finally, but I don’t want to burn her again (seems a sensitive strain). Suggestions as to strength of feeding to give. Pro mix is still moist from last water only feeding and I don’t want to overwater but feel I need to get some nutes into her ASAP.

Over water, too much notes, water when dry with cal mag till cleans up

Never seen nitrogen toxicity in plants that young. What hell dude?

i grow in pro-mix HP. plant that size i would give 1.0EC or 500ppm at every watering. pretty tough to overwater in pro-mix HP.

i start my girls round 1.0EC every watering in veg and get up to about 1.6EC every watering in flower

The nutrient burn you see on the leaves is not the problem, the damaged roots that causes them, is

pulpoinspace said:

i grow in pro-mix HP. plant that size i would give 1.0EC or 500ppm at every watering. pretty tough to overwater in pro-mix HP.

i start my girls round 1.0EC every watering in veg and get up to about 1.6EC every watering in flower

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Thanks I will try this next feeding. And yes I agree Idon’t understand how it could be overwatering. I’ve always let the pot dry out til it is really lite then only water til it starts to just come out the bottom. Is it possible I got a bad batch of pro mix and it is holding the water too long. I even added some perlite to help with an already good draining problem.

Obepawn said:

Never seen nitrogen toxicity in plants that young. What hell dude?

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Exactly I’m gave them 25-50% of the recommended for seedlings and this is what happened. First time with these Green Planet Nutes maybe just really concentrate I don’t know. Will try using EC/ppm as suggested above for better control.

Too much watering, there is even algae on the substrate. It's not so much nutrient burn, but looks more like root rot to me.