Hey wardrobe
My ph is around 6.2 but that's for hydro, I believe dirt is the same. The small containers might be making them root bound. probably best to wait till the next grow on that might stress them too much. here's a site i find very helpful:
http://sharprubberduck.com
Ph of 7 will slow down the intake on some nutrients so you might want to lower that. Try slowly at first [6.6] wait a week, see how they respond, lower them a little more till you get them to 6.2 or so.
As far as UK based nutrients, sorry I can't help you out there, possibly a hydro shop there will have some.
You have a good handle on things, far better than I did on my first grow , my hats off to you.
hope this helps
peace
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heartsurgerysurviver Reviewed by heartsurgerysurviver on . 27 days flower heres some pics of my superskunk 27 days into flowering,when should i expect the buds to start filling out as im pretty sure they have stopped stretching?the tallest is 3ft 3" and the tallest when put from veg to flower was 21" also im planning on getting epsoms salts as the leaves are loosing colour-can any1 tell me how much epsom salts i should add to 1 litre of water? Rating: 5