hi all,
i'm 3 week into flower with some Hog clones . they growing in cultiliene rockwool slabs, fed with vitalink bloom.
normally, as happened when in veg the ph gradually rises over a period of 3-4 days and i come and lower it to 5.5. this has been the way since i started growing.
however, for some unknown reason, the ph is dropping quite severely each 'day', dropping to 4.8. it drops 0.5-1.0 each 'day'
also it take quite alot of pH up to raise it, 10ml to raise 0.5-0.8ish.
i remember using ph up a while ago and it only took a few drops to substantially raise pH....

anyone use slabs to grow? could they be part of cause? i thought rockwool was a bit alkaline???

anyone experienced something similar? if so please share your knowledge (and possible remedies/solution).

Thanks all,
YDL

I know NWM has been suffering with the same prob but you'll have to get in touch with him, can't pm him myself......

to much n in the flower nute i have had this prob since vitalink changed the ratio year or so ago when it changed to max
i tryed on the last run to put less flower nutes and more pk 13/14 helped my ec out but still way way to high in n for me
its not much dif in npk to there grow...im trying growers ark this run used to love vitalink but since the change in npk and name to max its been a pain in the bloody arse

alternatively I'd check your roots if possible as dropping ph is an indicator of problems down there...

bacterial or some sort of nasty methinks or root problems try some microbial or pythoff in ya tank should stop the ph falling
and next time you start a grow do a real good sterilizing of all ya equipment

What size is the res?

Could be an ok res size for smaller plants but not for the size of the plants now.

Just a thought.

Don't think size matters in this case I got a loft tank res (200 liters) and that doesn't make any difference from clone to chop, but I've got my girls dialed in good so the levels tend to stay the same...

yer right bout change to max, it has been a pain since it changed, trouble is i a few gallon of the stuff cos greens got an order wrong and sent me loads by accident:-) i offered to send what i hadn't paid for back but they said forget it, don't matter.
so i got loads of the stuff so i might has well use it, like you i was gonna try summat new, genesis formula or summat. never tried a 3-part nute...

ph kind of leveled out eventually at 5.5, sometimes i needed a bit (nothing like the amounts i was putting in before) of pH up. the only thing i did was proper flush all system over 3 days, i takes a while to properly flush when using slabs. i flushed sysem 5 times in 8 days during last flush week , was only after 3 flushes that the water coming from the slabs came out EC-0.0. so there is a lesson for anyone using slabs, flush them at least 3-4 times before you chop em if you want nice 'clean' plants...

next lot of hogs are rooted, they are going into slabs (cultiliene are way better than their grodan equivalent) so we shall see if i've learned owt...

cheers for reply nicedreams and all whom have replied.
respect

(res size 250 litres btw)