any help with my seedlings?

Hi all,

I have 8 seedlings that are about 16 days old, starting from when I first hydrated the seeds to start germinating. They germinated between 2 to 5 days later, so they're effecively just under 2 weeks old if you count them from the time that they've 'popped up.' The genetics are good, 2 plants are Mandala #1 and the others are Nirvana Blue Mystics. I've grown the #1's before, but not the Blue Mystics.

Anyway, 2 days ago I noticed one of the Blue Mystics' 1st set of true leaves turning brown-ish and getting dry to the touch. They're not totally brown, but don't look nice and green like I'd expect. Next day they were dry and crumbly to the touch, and today one of the #1's are also showing this sign.

My setup is not ideal, I know that the temp is high, but don't have a thermometer so don't know how high. My guess is 85-90 degrees. I've started other plants in this same setup, though, and they were ok. Plants are in a small DWC setup with a bubbler going, lights are on 24/7. I have a 50 watt LED panel supplimented with a 70 watt CFL bulb. Not a lot of light, but it's proved to be enough to get things growing before. I can't add more CFL bulbs as they generate too much heat and will heat up the box too much.

No nutes yet, just plain water. My PH meter crapped out on my so I don't have a PH reading. Usually water here is just above 7. As the seedlings don't need nutes this early on, I'm guessing that it's ok to have water with a PH this high. Should have a new PH meter within the next 2 weeks.

So any idea what could be causing my problem? Too high heat? Is my fairly high ph actually causing problems? I can throw in some PH down, just don't have any reliable way to test the result currently. I also just got a new grow tent and have moved the seedlings into it. They're now under a 400 watt hps-- about 4 feet above the seedlings so there's lots of space, and the tent is considerably cooler than the grow box that they were in earlier, so if this is from heat stress, that should help. Any input from you all would be appreciated! I don't want to kill these seedlings!

Do you have ventilation for that 400? Ph in a DWC bubbler should be 5.6 so above 7 could be a problem.

hoping that passive ventilation will be enough in the tent, I have the ballast out of the tent so that's not contributing heat. I have vent flaps open at the base of the tent and tube shaped vents at the top open, so I'm hoping cool air will be pulled in at the bottom as hot air escapes at the top. Lamp is off currently (I run it at night when the house is cooler), temp is 70 degrees in the tent. Yesterday was my 1st day working with the tent and it was definately cooler than in my grow box, I'm guessing 80-85 degrees. I have a theromometer now and will check it again this afternoon when lights come back on (I'm running 18/6 lighting currently, as I have my seedlings in there and some autoflowers that I'm growing out for seed and are about 1-2 weeks from harvest). I have an oscillating fan I could put into there to move air around, but no other ventilation equipment currently.

I also changed out my water for the seedlings, added 2.5 gallons fresh water with 1/8t ph down (wish I had a working ph meter, I have 2 and both have broken) and a couple drops of superthrive. Planning to start feeding nutes in the next few days, probably just 100ppm or so to start as the plants are young still and have already been stressed. Last couple grows I started nutes too late and suffered nitrogen deficiencies, so I want to start feeding this one earlier than other grows.

Lights have come on, temp is 87 degrees inside the grow tent. I'll get my little oscillating fan set up tonight also, should drop the temp some as the room temp is 55-60 degrees.

lower your ph bro, for DWC you should be between 5.6-6.4

Got ahold of a ph meter, yeah PH was 7 in one bucket, 7.5 in the other, too damn high! Got them both dropped down to 5.2, expecting them to rise up for a while as the plants recover. 24 hours later I'm already seeing darker green coming into my seedlings. I'm able to manage temps in the tent between 85 and 87 degrees with a 6 inch oscillating fan inside and the vent flaps open at the bottom of the tent and the tent door unzipped at the top. Light is on 18 hours a day as all I have in there right now are my seedlings and some autoflowers. I plan to get an air cooled hood set up soon for my hps lamp, which will further allow me to control my temps. The seedlings don't look great, but are improving. Wish I'd caught this 5 days ago.

Pic:



Also a shot of my poison dwarfs for the hell of it. You can see they've also suffered from lack of PH adjustment and nute overdoses. I'm taking much better care of my plants from here out. These plants are amazing, though-- 10 inches tall fully mature, 70 days from seed. I'd have cut them down a week ago, but I'm growing them out for seed. I'm guessing I have 1-2 weeks left before the seeds are mature.

How close would you put a 400 watt MH to one week old seedlings. Thanks

I don't own a MH, but am guessing it would be similar to HPS as far as distance goes-- other 'pro's' are of course welcome to correct me. I've been told that 18" from the tops of the plants is ideal to keep the plants comfortable temp-wise. I'd be much more careful with seedlings. I have about 4' of distance between my 400 watt HPS bulb and my seedlings. They seem to be doing fine, no sign of heat stress or "burning" from the light. I believe that "light burning" looks like the leaves are bleaching out and turning white-ish, rather than yellow or necrotic, which would probably indicate nute deficiency or a PH imbalance. I've successfully started many seedlings using just a couple 26 watt CFL bulbs and/or a 50 watt LED lamp. They really don't need much to get started. My 400 watt is overkill, but I have the space for them in my current setup so I'm using it. Hope this helps, and again others may have better informed opinions about metal halide bulbs than I.