Please HELP!! I can't figure this out

I'm growing some Grand Daddy Purple, plants are about a month old. I originally thought the problem was over fertilization or pH problems because my pH was fluctuating quite a bit. I finally got the pH fixed at about 5.8 and saw a little improvement for about a day. Then leaves curled under real bad (eagle claw) and the dead spots on leaves continued to form and eventually the whole leaf would be fried. So next I flushed with 7.0 pH water (filtered, UV lights, RO>> clean water) because I though it was possibly over fert and salt buildup. I have flushed for 4 days now and the runoff water was at 6.5 pH with a ppm of 120. The curling leaf problem has seemed to subside but now the tops of the plants are turning a very pale green, stems at the top are purple, and fan leaves are yelowing/browning and getting crispy. I thought this was now a deficiency but the weird thing is that the lower branches look fine (much healthier green). This made me think it was possibly getting fried by the lights but temps are never above 85 and are usually about 79-81 with plants being a good 18 inches away from lights. Some one please help!!!

Over Fertilization still?
Temps too high?
Nutrient Deficiency?

Also, the stems of the leaves are VERY brittle.. I'm pulling off leaves everytime I look at them

You can rule out heat IMO.

This looks like a calcium or micro nute deficiency which can be treated with Botanicare Cal-Mag.

I have GDP too and had the same problem, except mine was caused by root aphids that are raping the plant of nutrients.

I would start by leaching your medium with properly PH'd water, and then apply a feeding ensuring you give them some calcium. If your nutes don't have cal in them pick up some cal mag by Botanicare.

Also go here for plant trouble shooting:
https://www.rollitup.org/marijuana-plant-problems/216537-self-diagnose-your-plants.html

Sorry about your plant problem. I won't try to diagnose your plant ailment as that is a very tricky thing to do online and I don't want to give bad info, but here is a link to a Website that has valuable info and pics on plant problems. It may help.
http://www.greenmanspage.com/guides/plant_abuse.html

Thanks for the reply! I actually happen to have some CalMag but stopped using it because I thought it was possible over fert before, now I'm thinking it was a deficiency all along. I will be flushing and hitting them with fresh nutrients today (including CalMag). Also about the heat issue, I honestly didn't think it was that but it was strange how all the leaves and branches that were sort of shaded from the light down below were doing fine and looked a much healthier green. I'm guessing the deficiency is just affecting the tops of plants mostly. Anyways, thanks again for the advice!

1st off i am no expert. do u have max min temp gauge + max min hydro meter + u r using lrge rockwool cubes as stand alone medium - most people would house the lrge cubes in a large pot with another medium such as clay balls ( i say this as the way u r at mo ph and nutes and available food will fluctaute massively because of the small amount of medium u r using)

so my advice is gr8 u have flushed loads - can never harm. get all your stats together - keep a chart if u have to

also maybe change your nute manufactorer as what u using now just may not suit your grow at mo

oh and when u are feeding is the temp of the water with nutes room temp?

are u venting aswell as using a desk fan for fresh air flow?

all i can think of right now gl dude wish u had posted sooner and lastly pull off fan leaves 505 dead or worst

all the best

I have the same thing I just started my thread earlier
I am growing in dirt but the ph of my water was over 7.5 and I didnt realize it cause I moved
I am assuming its Cal mag deficiency

A very quick and easy way to help these plants is to use a foliar spray of 1/2 teaspoon of Epsom salts to a gallon of Ph balanced water, works wonder for Mg deficiency.

I think you nailed it already Cory. Definitely pH damage. This is probably the accumulation of a lot of time with that iffy pH. Flushing was the right call. The leaves that are more than 50% dead you may as well remove. The stuff that is toasted isn't going to get better. Add a few days extra veg time to compensate for all this stress also. Keep a close eye out for hermaphrodism too.

The nutrient damage is related to micronutrients like Calcium and Magnesium. I also can't rule out other elements given the pH issues.I think they look a little hungry post flush, You need to get your nutrient levels dialed in. If you were running too much before you should probably back off to 2/3 strength and see how that goes over the next 3-4 days. Keep an eye on the new growth. The sick leaves may just be too dead to support themselves and you could wind up treating an issue that's been resolved but has yet to conclude.

My questions are:
What is your water source?
Have you tested the ppm levels of your solutions?
What specific nutrients are you using?
When did you last calibrate your pH meter?

Hope I can help.

Thanks everybody!

I am using filtered water out of a machine.. They advertise that is filtered through certain microns, then treated by RO then treated with UV light. Perfect 7.0 ppm are like 13 when I start. I am using Advanced Nutrients' micro grow bloom and kept the ppm to 500 this time (also using cal mag, hygrozyme, bud candy, vitamin b1, and some drip clean) so we'll see how this goes.. Plants seem to be getting better but pH is still fluctuating a bit (it keeps rising). I have calibrated my ph meter recently (although I only use the 7.0 solution).

If this doesn't work I will try foliar feeding with Epsom salt.

If you've been using Phosphoric Acid pH Down (General Hydroponics) this can cause the instability in the pH.

Switching to TechnaFlora's Nitric Acid pH Down would provide you with more consistent pH levels. It's only about $7 a bottle at plantlightinghydroponics.com, I just got a bottle for myself.

Calibrating at 4.0 is important, very important. You're going to need to sack it up and get that solution. It's a bummer that pH issues are so expensive to manage but it just isn't worth taking chances with. Gotta get the meter, the calibration solutions, the cleaning solutions, and the Up/Down. Hundreds of dollars later... and you want to skimp on a $4 bottle of 4.01 calibration solution?? C'mon now, you know what you're supposed to do, you don't need me to tell you.

I'll have to try the TechnaFlora. I've got a generic pH down & up right now and I have always had pH fluctuation problems so definitely gonna pick up some.

Yeah, your right, $4 aint much, it's funny the things I choose to skimp on while all the expensive shit has already been purchased! haha

Plants are looking great though now that I've gotten the pH stable at 5.8..nice healthy green color is finally coming back. Thanks for all your input!