Low Soil PH.........How can I raise it ?

[Rusty Trichome]

I am using the liquid test kit, when i tested the run-off water i filtered it through kitchen towel first, the water looked clear before i tested it, but i do realise they are not the most accurate way to go.

Bleach and detergent residue will also skew results. Doubtful it's the soil ph that's out-of-whack. :thumbsup: Have you tried ph'ing plain water through the towel? Just curious...

They've been in 1 gallon pot for 5 weeks, too small and too long in one place i know, but the plants are quite short and i was hoping to finish them in these, though i know i'll have to repot them if i want to keep them really happy. The thing is i've got 6 clones nearly ready to flower and if i go for bigger pots i'm gonna struggle to get them all in my space, so i'm kind of torn about what to do, also i can't get anymore FFOF for a few days.

Going to have to make a decision. Save the time and effort already invested in the rootbound bunch (transplant the adults)...or focus on the new. Or, a combination of both. But in the future, might help to remember that 6 weeks of root growth is 6 weeks of root growth...regardless of size of pot. Plus, a more-confined rootball means less organics (soil) in the pot, so they're freaking-out. Got any old soil you can flush and re-use for transplant? (emergency measure only...not intended as an everyday technique)
Likely this is a major contributer, along with any (incorrect/inappropriate) corrective measures that have already been taken. Not saying that there has been, but thought I'd throw that out there, see if anyone catches it. :thumbsup: It's painful culling a perfectly good plant, but if you can't make it work, they all suffer. Perhaps keep one or two adults, (but keep canopy as even as possible) and concentrate on the clones. This keeps your adults going for earlier consumption than you'd get keeping only the vegging clones. Plus it's a great learning experience, taking them from the plant problems forum, to harvest.

What would happen if i didn't do anything ?

Likely the same thing that's been happening.

... so i've got at least 5 more weeks to party time.

Stress can add weeks to total time to harvest. Fix the situation, and they may finish fine, but late. Doesn't take roots long to realize there's fresh meat available. :thumbsup: