More problems ph related I believe

Hi guys This is my first grow. i believe i am having some ph problems the ph going in is 7.5 and the run off is 7.5 also. stems are pretty deep purple new growth is light green. im using a product called seasoil which is organic so i havn't had to add any nutes yet. The plants are 6 weeks old. the tips of the leaves seem to be drying up and going to a brownish color and also there are whitish yellow spots on the fan leaves.

The strain is Skywalker OG Kush from Riserva Privada I have three girls and they all have the same problem.600watt hps bulb for lighting with a crappy home made reflector (low on funds) temps are 80 but i have seen spikes of 85 I'm gonna add another fan to bring the temps down abit.

Is it to late to add dolomite lime?
is neem oil a good preventative for spider mites?
Note: Pic 4 i attempted to try lst on my plants and cut the tips of that fan leaf to allow more light to some of the branching and the drying out that i was talking about has caused it to crumble and break away thats why it sort of looks like bugs.

yes purple stems indicate ph . high ph will lock up plants and it will not be able to absorb and nutes. so get the ph proper. and flush the plant heavy with the proper ph water, you will be ok in 2 days or so !

go to the hydro store , or a pet store that sells fish , or a swimming pool store . but get a ph up and dpwn and a tester . costs 20 bucks or so

ok. Thank you for the quick reply. how heavy are we talking they are in 3.5 gallon pots. and about the dolomite lime can i add that now or is it to late. thanks again

also i just did that today i bought all of that good stuff and thats how i found out my ph is out of wack what do i adjust the ph down to?

6.5 if that's soil.

ok thanks and it is soil its called seasoil its pretty much the same as ffof so i was told. And what about the dolomite lime? anybody?

Also what would be considered a heavy flush in 3.5 gallon pots?

overwatered is all I see...its NOT pH...in soil soiless it is very very very rare that pH is a problem

Those plants look good other than the minor pH stress. Getting the runoff pH between 6.5 and 7 would make it a lot better though.

I forgot to mention since you asked, do not add dolimitic lime. Your soil is probably limey enough since the pH is too high.

Dolomite lime will raise your ph, you want to lower it.
Use pH down (usually sulfur)