Top leaves wilting, PH or zinc issue?

Hey all, i'm on my second grow and having some issues with my top leaves. I just started my flowering so i'm trying to nip this problem in the bud, literally....
My top leaves have strarted to wilt and curl in and down. This is especially happening at the ends of my leaves. I think i also have a little bit of nute burn but have flushed to fix that.
I am using a miracle grow 3 month release soil, and tap water. Yeah i know but it's what i had and it didn't cost me anything.
I've read alot of the troubleshooting guides for plant problems and the only ones i can see that could be the issue are PH and a zinc deficiency. I've checked my water PH and it is about 7.5. I do not currently have a soil PH meter so at this time i cannot test the soil.
Is there a solution i could add to the water to correct the PH issue or should i use a bonemeal to lower the PH in the soil? At this point i'm leaning towards the PH issue.....
The plant is still healthy at this point and i don't want it to go down the wrong path. Anyone with some advice on how to fix my problem please let me know!!

Thanks all,,,,,

hey bro, i'm having the same problem except im longer into flower. same tips burnt, top leaves wilting, but the lower nodes look ok but the higher up you go the more it wilts. using MG with tap water and bloom boost. Fully CFL grow. so i guess its the soil , and maybe the tap water . Believe me, DON'T use MG its a last resort, your plants will not look as good, or have a good harvest. MG nutes suck and its the same price as organic soils. This is my 2nd grow too and I can tell ya, get new soil, keep mg in your root ball, but get them into a better soil if possible.