tent problems ,yellow,curling,crunchy leaves

i am having trouble in my tent with slow growth yelow leaves curling at the tips and very cruntchy .i first thought it was the pvc tent so i changed to a mylar tent.1 out of the 4 plants is doing ok the other 3 are very slow growth .my ph is 6.2 to 6.5 they get watered every 3 hours for 15mins(fast drip)
i have been flushing with water for the last 8 days .i thought it might have been a feed buildup .but the waters comming through clean .roots are in oxygen fed water
i run everything the same in 2 other rooms with no problem ,i only have this problem in the tent,same temps ,same feeds ,same seeds ,i'm stumped .i hope someone has some good ideas
thanks
i'll try and download some photos

I forgot to mention there in the 4th week of bud

Did the yellowing start at the top?

no yelowing started on big leaves then spread but mainly in the middle

Are you using the same water source as before? When i started using RO water, some strains i have to use a mag/cal supplement

all the water for all 3 rooms comes from the same source
this has got me stumped .would bad ventilatiom have a posibility of doing this kind of damage

It is not a toxic tent, it starts to yellow from the top down i just had to git rid of a tent that was killing my plants. You can smell the gas that is released by the heat in the tent it smells like shitty new plastic.

i have already changed tents a few months ago ,i now have a mylar tent

i tink it is airflow. i have been having this problem too, seems to be only in tents and happen when the intake fan goes off for me.

edux10 said:

i tink it is airflow. i have been having this problem too, seems to be only in tents and happen when the intake fan goes off for me.

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i have a tent aswell and mine look like the last pic.... i added an intake and already had an exhaust .. maybe that will help because im out of ideas too

A few questions for you. What is under the clay pellets, is that rockwool and if so how much rockwool are you using in comparisson to clay pellets. Also, since you are essentially growing in hydroponics why is the pH so high? I would have thought a pH of 5.5 to 6.0 was the usual range for hydro. Also what are you treating your water with in terms of bug treatment for the root area (assuming you are using a recycling res)?

Then there is the issue of ventilation, are you using forced air in and out?

Lastly what are the temps around the pots level, at the level of the canopy and the overall air temps in the tent?

Added: also what is the temperature of the nutrient tank

crazycanuk said:

i have a tent aswell and mine look like the last pic.... i added an intake and already had an exhaust .. maybe that will help because im out of ideas too

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do you have oscolating fans too? i had intake and outtake too, they are very temperaments.

whare are your intake and out take located? could be that fresh air is just being left on the bottom of room.