if i may suggest something, that tin foil you have in there is not going to help ya. It will produce hot spots and potentially kill your plants. IMHO, i would remove it and keep the white that you have on those walls which are plastic. If you wanted something more reflective get yourself some mylar.

The tester you have is a piece of crap, doesnt read the ph correctly, get yourself a digital pH tester or borrow one from someone and look at the different reads. The best thing to do is to test and see which is best for you. I found that the digital testers are best and those needle ones are junk.

Your gonna need to get a fan in there, the reason you have those stakes is cause the main stem is not strong enough to hold them up on thier own. The fan will stimulate the main stem and it will get strong enough to hold it up on its own.

Im not sure how old they are, but if they are fairly young you could have the start of stretch working there, you might want to increase the amount of light that they are receiving.
Other than that i havent seen anything else that i would change but as i look around and find things i will let ya know..

Hope that helps