Yellowing of middle fan leaves and tips of top leaves looking burnt???

Damsels in distress...help!

Okay so Plants are around 7 weeks old and were transferred from 250w CFL to 600w HPS just over a week ago, All started of great and they were loving the new light! so i left the house for 2 days with the lights and fan on 18/6, The average temp has been 75f - 85f and humidity between 50%-70%

when i returned there were a few dry looking yellow leaves(not loads and only on some of the plants) Also on 3-4 of them the new leaves looked slighlty burnt at the tips???

I'm using plagron bat mix with hydroton clay pebbles (which were soaked thouroughly in 6.5 ph water)

dont get me wrong they are not on deaths door i just thought i'd nip it in the bud before it gets worse(pardon the pun!)

Check out the pics, i have no idea whats wrong with these ladies

cheers

Pics should be up within the hour!

Reduce your pH to 6 and post the NPK of the fertilizer you're using.

My suggestion is to dial back you nutrients by 20% and to run your ph at 5.5 to 5.8. Try to keep your temperature and humidity a little lower while you're at it, top out at 82 and 60%.

cheers guys

not using ferts yet , however i did top up the soil without watering through 1st so i think its just a bit of burn from that, they seem to be outgrowing it by themselves. Ill drop the PH and let you guys know, thanks again

Ladies are lookin sexy again thanks guys!

Now for all those sativa hybrid growers, How big are these babies gonna get under 600 hps for 13 weeks??

they are around 16" right now and i am limited to 1.8 meters, should a start flowering immediately? or let them grow a little more?

I've only heard rumour about the light of jah strain, so im worried they are gonna grow crazy during flowering, can anybody shine any light on this?

peace

I'd flower now and hope they don't get much larger than 1m. Sativa's can triple in height from the start of 12/12 to harvest.

Since there are some varying suggestions, you can find the company's pH reccomendation here:

http://www.plagron.nl/frontoffice/uk/Producten/Substraten/bat-mix.html

Snow is, of course, correct about flowering now and Sativas do predominantly at least triple in height during flowering. Our "short" Sativas start at about 8" and finish over two feet. That's topped multiple times and they can grow even more untopped..

i'm sorry to jump on your thread but i'm having the same problem.......bottom leaves are almost yellow and the top leaves have brown spot in the middle of them and the tips look reddish brown as well.... I'm using nova bloom, floralious, liquid kool bloom, and pineapple rush. The plants go through a gal of nutes in two days so i thought i was over feeding them bygiving them nutes that much so i flushed with nothing but ph bal. water and it seems to hav gotten worst. I'm 5 weeks into flowering and the buds are coming along nice. I dont want my plant to die this close to harvest. should i go back to feeding them every two days??? any info would be appreciated!!!!!
follow my thread please!!!!!