Pale leaves at the start of flowering

Possible ph skewing, causing yellow all over. Don't see a mobility present which leads me to think its a alkaline pH most likely too much cations from the hard water, this would affect a couple of things. The higher the pH slides alkaline the faster nitrification (breaking down of organic nitrogen). If the rate of breakdown exceeds the amount of nitrogen being utilized it can very quickly skew pH balance, which will quickly present N, Ca and Mg symptoms. If it was a single nutrient deficiency I'd expect a clear mobility of the nutrient that's deficient. In order to properly flush organic nitrogen from a medium its recommended to use 4 to 5 times more water to completely remove otherwise the ph will just rapidly skew again shortly after a regular flush. Hard water can be a pain as its full of ca and mg.