LEAF ISSUES - Northern Kush (N.L x Mstr Kush)

Hi everyone, I have been an avid "reader" on rollitup for the past year or two, I have learned more on this website than I could anywhere else.. (applause..) I usually only post when someone needs help or when I need help...

I seem to have this issue around the same time every grow. It starts with the bottom fan leaves... the leaves start with tiny brown spots on the 'inside' of the leaf, the leaves seem to turn a little brittle after a week or so, then the condition of the leaves slowly gets worse, moving up the? plant.?

medium - 6" rockwool recently planted in coco/hydroton
ph- 5.8 (I just got a new electronic PH meter 2 days ago...) the ph was around 5.4/5.3 before when this started.
nutes- 3 part GH, superthrive, fulvic acid, floraliscious plus, cal-mag... I use atleast half of the recommended dose, and adjust as needed.

Here are some pics, the issue seems to be affecting all of the plants, there was a a little "burning" of the leaf tips before the brown/grey spots formed.. I initially suspected a Magnesium (mg) or a (mn) defficiency however in my past grow i have added epsom salt and the deffieciency only progressed, I also suspected a phosphorus (P) defficiency seeing how one plant has both brown/yellow spots/chlorosis on one leaf (mg) and a greyish/brittle spot on another leaf (P)...

The only thing I have yet to do, which I will soon... is buy a ppm/tds meter.. my tap water has a high PH, so I believe it must have a high ppm too, which I have heard can cause certain deffiencies. I have read that a PH of 5.2-5.8 is best for hydropincs, will my recent transfer to a 60/40 coco/hydroton need a different PH? also I have heard of a PH above 5.5 will lockout Mn... which may be the culprit in this thread..

Please check out my pics, n post.







heres a new and very informative link:
Marijuana Ro Medical Club & Community - Nutrient Profiles and Deficiencies

Ph for Hydro is 5.6 to 6.2. You may have ran yours a bit low causing some lockout in the past. Your pics do not look to be too bad of a problem. looks pretty good, even the healthiest of plants will have non perfect leaves.

haha, yeah i know, i have had half of my crop burned due to this issue before, although then I had multiple strains and no ph of tds meters, I have learned my lesson. The rest of the plant looks extremely healthy, theres about 7 nodes and shes right around 14", looks like a bush, thats why shes my mommy, any way the 2 or 3 leaves with problems are the lowest fan leaves and i believe I should have it under control...

still replies welcomed..

let me know if a grow of train wreck, N.L.xMstr Kushm, Thai x S.Skunk, Cheese, and about 8 random strains.. possibly God Bud and Dreamweaver, would sound interesting and be beneficial to anyone..

I do God Bud and cheese. They are wonderful strains.