Help

well, my plants went from being perfect to almost dieing within a day and a half. they are yellow edges curling upwards that feel like they're burnt with brown spots on the edges of the leaves. i didnt add any nutrients. i'm using miracle grow organic mix, sphagnum, perlite, and osmocote mixed. osmocote ratio is 1/4cup per sq ft. they're 2 weeks in and dont really want to start again. my other plants are showing some symptoms but not much of the same problem.

http://tinypic.com/r/34yduzp/5

the pic above is the one that is the worst.

my ph is also 6.8.
temp is constant 79F
humidity is around 30% normally.
lights arent close and i'm using 4 65w CFL cool tube about 5 inches above the plant.
also i dont over water them and check the soil before every watering with a ph of 6.5

i think it may be potassium K deficiency since my humidity is always low. but its honestly my second grow and its winter time here. my last grow ended beginning of fall.

Looks like light burn and humidity issues. How about a picture of the whole setup so we can further help you?

this is my setup. that dehumidifier isnt running nor has it been ( front left corner ) i raised my lights about a foot and a half above them now and i put plexy-glass in my ballasts with dual exhaust at the end of each ballasts ( there is two total ) each ballast has 2 65w CFL 6500k. i currently ordered a humidifier but i dont know if it'll actually put in moisture before the exhaust takes it out. the only difference between this grow and my last one is that i had a higher humidity. same dirt mixer and osmocote ratio. also i'm probably going to seperate them into individual containers when it becomes flowering time.

this is what the plant looked like the day before it went to shit. i didn't add anything extra but just plan water. the PH on the water that day was 6.9 though but the runoff came out 6.6.
the picture to the right is from my last grow. so you can see how i can grow. i'm not a novice but this situation has my dumbfounded

Raise up the lights, also are you using any of that hydrogen peroxide you have right there? I wouldn't use that cuz high doses of that could do that also.

oh no, thats just for comparison. closest thing i had to match it. i use vinegar if needed to neutralize PH. i havent used it in this grow though.

i just looked up humidity. yea thats what it is. it specifically says that the tips will brown then the margins with get dry and cup. which is exactly what is happening. thank you LarryOG for bringing me to the light. haha, i'm going down to true value to pick one up ASAP. it wont help the damaged one but it'll help the rest that arent showing much signs of it.

well, i added a humidifier with a auto regulator set at 55% to 65% leeway, i hope this works, haha.

For your information low humidity won't do that. I have grown in 20% humidity and grew just fine. I can't think of why she is growing like that. I have never seen that before. Just know it has nothing to do with low humidity. Are your fans blowing hard onto the plant? could be wind burn??

fan just makes them move a bit not much though. but i did read that low humidity can cause closing of the stomata and that causes low metabolism rate to the point where it'll lock all co2 and lockout of nutes.

the only difference between this grow and my last ( which was great as the picture with the 2 0z kola next to the peroxide bottle ) was the humidity. last grow was 50% humidity and this one is 15-30%

Ok as long as the fans are blowing a bit then you should be fine. However don't believe everything that you read. Do you take the temps above the canopy or just the room area?

well i believe i fixed the problem, i got a humidifier and just added regular h2o with 7.0 ph ( my ph was a little low yesterday) man did they go through a growth spurt. haha, its alll good now.

i set the temps honestly right below the lights for security measures of heat damage and i have a light sensor that tell me its getting around 1700, it only goes to 2000. i have 3 temps though the other 2 are right below the plants and one up on the ceiling so i can get an overall average the grow area. each temp gauge has a humidity sensor as well. well, i read multiple professional growers saying winter time is harsh on the plants stomata causing them to close and destroying crops over low humidity but in summer low humidity is alright since the ambient air is moist everytime i open the tent keeping it "misted" basically.