High soil pH causing P/K deficiency???? - please help!!!!

[geomana]

Hello. I'm a first time grower, growing outdoors in the valley in northern California where there is full sunlight all day. I'm growing in 90% organic compost from a local worm farm and 10% perlite and coco fiber. The well water I'm using is very clean with a pH of 7.0. I've been using Sugar Peak Brand organic soluble nutrients on the soil occasionally, though the compost is very rich to begin with. A NPK test I did recently shows that there is sufficient levels of all three. My plants look to obviously have a phosphate deficiency. Many of the fan leaves are withering away in that special manner characteristic of phosphate deficiency. However, having tested the soil for phosphate, I'm thinking pH is the problem, locking out the phosphate from the roots. Take a look at the pictures and please tell me what you think. I don't want to start adding sulfur to my soil unless I'm fairly certain that pH is my problem. My cheap plastic pH meter is pretty variable, reading between 6.8 - 7.8, averaging at about 7.5, which, from what I've read, is quite a bit too high. However, it could be the cheap meter (which I don't trust).

The first few pictures show one of the plants I have in a veg cycle still (supplementing daylight with grow lights at night to get it a bit bigger before flowering). It has troubles standing up (which I believe might also be caused by the roots not growing so well due to nutrient lockout) and has the withering fan leaves which look like classic phosphate deficiency.

The next set of pictures show my flowering plants which have the nute deficiency much more severely (probably because during flowering they need more P and K than they did during vegging).

Should I send my soil in and get it professionally analyzed? Should I add aluminum sulfate to lower the pH?

Please help!!

[geomana]

Anybody? Please???

[blakeshouse]

Throw some dolomite lime around the plants and use epsom salts in the water it will brong that ph down

[geomana]

Actually lime raises pH. Also I have my doubts that epsom salts actually affect pH much. I've done enough research on my own to know that if I need to lower the pH of my soil then I should use aluminum sulfate (garden sulfur). However, before I go out and spend a bunch of money on the stuff I'd like to get some second opinions from some EXPERIENCED GROWERS.

Here's the strange thing. I planted peppers, tomatoes, squash, eggplant, and corn, in the same exact compost and they all did fantastic, exceeding my expectations many times over. So why is the cannabis having such a hard time in it (considering the fact that peppers, tomatoes, and cannabis all like a similar pH)?