Help quick! seedlings brown spots!

Hi, I have attached some pictures of what my seelings have started to look like in the last day. I am concerned about the slow growth and also the small brown spots on some of the leaves. Here is all the info:

400W metal hailide light approx 3' above the plants
The seedlings are about 4 weeks old. They were transplanted to the hydro setup about 5 days ago.

The pH has been kept at a constant 5.2 or in that close range, but when I woke up this morning it was at 7.1

Water temp is about 68 degrees farenheit.
Water cycle is on for 15 minutes twice a day
Light is 24 hours
setup is a 2'x4' ebb and flow system


No nutrients are being used at this time since the seedlings are still young and the roots aren't quite developed. We added a tiny tiny bit of superthrive to the pH balanced water but it didn't really seem to do anything.

Shit man I have no idea. I was going to say nute burn. Looks just like what I’ve had.

Hi, we actually added some nutrients for better or fore worse because we believe that it is a phosphorous deficiency based on the attached picture that I came across on the net.

no, you plant cant get a def. that young

I think maybe you should change the irrigation cycles. Instead of 15 min 2x a day try 15 min every 2.5 to 3 hrs. Those plant are sitting in hydroton and they aren't extracting any nutrient from those rocks. They look hungry.

Good Luck Amigo

Also instead of 24hr light, try 18/6. During dark period plants seem to grow. And also keep the pH between 5.5 & 6.5.

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Originally Posted by muordeeb

Also instead of 24hr light, try 18/6. During dark period plants seem to grow. And also keep the pH between 5.5 & 6.5.

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plants grow fastest with 24 hours of light. I agree that plants seem to grow more at night. but studies have show that plants grow fastest with 24 hours and grow 75% that speed with 18. This shows a linear curve between growth and hours of light.

Quote:

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Originally Posted by harris7

plants grow fastest with 24 hours of light. I agree that plants seem to grow more at night. but studies have show that plants grow fastest with 24 hours and grow 75% that speed with 18. This shows a linear curve between growth and hours of light.

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hey guys thanks for your help. We have made some minor adjustments that have seemed to help a little bit. We started with using superthrive the day I posted this thread and it didn't really help that much. I find this kind of odd since superthrive is made specifically for troubled root systems or plants that have been stressed. We only mixed the superthrive into the nutrient tank - we did not have nutrients in the system yet.

Since then we added less than 1/4 the strength nutrient solution for feeding. That seemed to help minutely but the plants should be doing better than they are now. I know some browning on the first two leaves is normal too. The temps have been a little high in there lately, we were thinking about putting the plants on a 15 min water cycle every 3 hours like we had when the plants were vegging full steam ahead, but for seedlings I thought this be a little over kill. It is quite possible that you are right though and the plants just need more water and maybe a little less light. I will try putting the system through its paces and see how the plants respond.

This is really a shit situation for a second grow. We were planning on doing this one the complete right way, only last time we used clones instead of seeds. What we worry about now is being able to get ANY females at all rather than 6 healthy plants. FUCK

Quote:

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Originally Posted by harris7

plants grow fastest with 24 hours of light. I agree that plants seem to grow more at night. but studies have show that plants grow fastest with 24 hours and grow 75% that speed with 18. This shows a linear curve between growth and hours of light.

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Plants do not grow faster with 24hr light, marijuana can only process 16-18hr of light per day efficiently. I've had plants to grow 6" over night.