some leaves thin, curled-upward, browning edges

[Weedhound]

http://boards.cannabis.com/hydroponi...t-s-wrong.html

I found it!! In this post there is a link to rockwool and its issues. Good luck.

[cigarettes42]

you use the same light for veg? my leaves did that when i hung my light too low to the plants. raising the light fixed it but not the leaves. i wasnt to sure on if you switched the light cycle with a stronger light or just the light cycle with your current light.

[stinkyattic]

Is that temp reading AT the canopy? Upcurled edges=lights too close as Ciggys42 said. Take a max temp right in the space where the worst-affected leaves are.

[Baruce]

Thanks for that rockwool link, Weedhound, very informative. I also think the rockwool retaining so much water led to the problem. It was suggested to me that the over-watering has led to root drowning, which is causing a nutrient deficiency, and that I should apply a foliage feed of sea teas and half strength fish fertilizer... not something I would want to do if I'm experiencing over-fertilization. So, I'm still confused.

I'm using the same 600w HPS for veg. The thermometer has a long sensor wire, which I have dangling so that it reads from the plant tops. The plants are about 3 feet below the light, good ventilation.

Given the temperatures and distance to the light, I highly doubt that the issue here is temperature-related. But I'm not sure what exactly is going on, so I'm still confused as to how to fix things.

[Weedhound]

When in doubt.....go low. If your plants have a def of some kind you will see it become more pronounced if you put your plants on a very low nute strength.....ph correct always of course. If the problem is overnute/overwater you will see them improve when you do this (and of course....back off on the watering) The way I was taught was.....undernuting will make your plants sick....but overnuting can kill them right off so when in doubt......go low.

If the temp IS at the top of your leaves however and it IS over 80 then you should definitely be thinking about a little less heat but as I said I can't look at the photos so don't discount what other good growhead minds are saying. ....do you have a oscillating fan or something blowing to help cool?

[Weedhound]

You said good ventilation....never mind. What's your room temps....and room humidity? Do you have a way too measure those? Just curious.....not necessary but I'm interested.

[Weedhound]

Since I'm wandering around stoned and babbling away....those grow nutes you've got sound like some pretty strong shit. I use Pro grow at 3-1.5-4 so I must say that with NPK numbers like you have there it wouldn't take much.....sounds like quite the power stuff.

[Baruce]

The way I was taught was.....undernuting will make your plants sick....but overnuting can kill them right off so when in doubt......go low.

Good advice!

I do have an oscillating fan as well as a vent fan. The max temp isn't at 80 often or for long, especially now that I'm at 12/12; usually I have readings in the low to mid 70s. I don't have a humidity meter though, I have to pick one up.

I gave them all a foliage spray yesterday and today of half-strength fish fert and B-1, and some Hydroguard to help protect the roots. I also added half-strength of B-1 and Hydroguard to some 500ppm/6.1pH nute solution and gave them each about 1/3 ounce right at the base. The rockwool cubes still have water in them, so I don't want to add any more than needed. Hopefully the foliage spray will deliver some nutes quickly, and the cubes will dry out further so the roots can resume their duty.

The Supernatural Brand Gro Aqua is 17-7-18, and it calls for 700ppm full strength. I started at about 350ppm, and recently upped it to about 500ppm as the kids grow. I'll be switching to their bloom solution soon, but I need to straighten this problem out first.

[Weedhound]

Update when you can......good luck.