Peat moss is a powerful buffer. Alone it sits around 4.5. Soil chemistry is an issue of the sum of the parts. If you can tell me what the soil mixture is, I can guesstimate what your pH should be. I have done experiments using about 4 samples of the same soil and running pH buffered water thru them starting at about 4.5 up to 8.8 and then testing the latent runoff with a good meter. Like I said, buffered water does not have a long term effect unless it is really radical, like watering with water that is 4.2 but then you have another problem on your hands - you've just burned the sensitive root hairs.
There is something wrong with your plants but no one can put a finger on it without knowing what you started with and what you're doing on a day to day basis. First place to start would be with the plant foods you're using.
If your top leaves are yellowing, then you're giving your plants too much light and/or too little N. Less is more. A photo using a flash, overhead room lighting, HPS OFF would do wonders to see what is really going on. The necrotic dots in the mid to lower leaves are not good. If the leaves are not productive, neither will be bud your production.
Being that you're now going into flowering, it's too late to scratch in a couple of teaspoons of Flowers of Sulfur as it must first be converted into sulfites and then sulfates via microbial action to have any affect. Normally I would prescribe about 2 teaspoons in the pot your using. Aluminum sulfate will give an immediate and long term reaction as will upcanning into a soil mix using more peat, which will permanently drop the pH. BUT, I'm not sure you have a pH problem. "It's pH" mantra that folks use often when they don't know what the real problem is. Pin down the problem before you add something that can and will do more harm than good. Mg chlorosis (deficiency) shows up in the lower leaves, sometimes middle.
Good luck,
UB
