well im on my 5th crop using my vertical cage now and every other crop went as it should, lovly deep green foliage and some pucka buds but this crop is entirely a differante story!

a quick run down of the feeding times, ect ect

i have used the same method for all 5 grows now and never had a problem untill now,i feed 3 times a day, 10min at lights on, 10min hr later then 5min at lights off, this has always worked with good results, all plants were looking sweet up till last week wen they started yellowing and dropping.

at first i thought the dropping was from over watering as the temps have been downa little bit but then i checked my run off and the ph was 4.9! so i flushed the sytem untill the run off read ph 6 which is ideal for rockwool.

so thinking id sorted the prob i went home and fort no more about it, went to the grow house the next day, checked the run off again and yep you guessed it ph 5! 5.2 being the lockout point!

so again i flushed untill the run off showed ph6, left for 2hrs then checked again and yep it droped to ph5! again after only 2hrs! this has been going on for nigh on 2 weeks so as you can imagine my plants are looking very very sorry for themselves. most leaves are yellowing now although they are trying to regain vigur the ph keeps droping over night to 5 or below so the plants cant sort themselves out.

im feeding them a very low ec of .4-6 as their realy stressed out and i got tip burn at .6ec. my ph in the res is a constant 6 but the run off is never over 5.3! wen i check at lights on! after dumping all 120ltr of the res through the sytem will the ph rise to ph6 but always falls rapidly!

any ideas guys? times running out and cant afford to loose the crop at this stage! 2weeks into 12/12

i always let my water sit for 24 h, the ph dose drop over night.
so try sitting it 24 h then adding nuts.

Is your ec meter correct? My experiance with dropping ph has meant that I have overfed

Try flushing out with ph adjusted water and recallibrate both meters.

not real sure what the problem is but flush the rockwool with lots of water at 5.8 ph a good flush what nutrients you use ?

cheers lads, yer tried all this so far.

all was looking sweet untill 2 weeks ago wen the ph started droping, cant be over fert as i havent got over ec.6 and im in 2nd week 12/12, got to .6 and got tip burn yet im usualy at 1.2 ec on my last 4 grows with the same strain using exactly the same method.

nutes are advanced 3 part with carbo load, fulivc, humic acid. big bud, m/earth bloom, barricade, and sensizym.

since the ph droped iv only feed with the 3 part feed so not to over load the stressed plants with all sorts of chemicals.

iv flushed 3 times now with weack nutes mix of .2-.4 ec, the plants are trying to recover as the new groth is nice n green but as the ph keeps droping below the 5.2 cut off point the nutes keep geting locked out over night so the plants only get maybe 2-3 hrs within the correct ph then it drops.

the ph in the res is prity constante around 5.8-6 yet the run off is always in the low 5s by the moring.

iv never seen or hear of this b4, looks like im going to loose a crop, this is a first for me and considering im doing exactly the same as my last 4 grows using the same strain and system im well and truly guted!

any ideas lads befor i give them the chop? dont see the point in keeping them if their not going to recover, might aswell cut my looses and put the 30 clones i took from these b4 i went 12/12 as their doing fine....thanks for any help...mrc

not really sure but sounds as your slabs have gone sour maybe due to a bad reaction with some of the chemicals you are using best to keep things simple with nutes only think i can say is flush with lots of water then try ec of 10 flush with a hose pipe all the slab hope it helps