It could be a couple of things. It could be your water. You need to use RO if your tap is over 300ppm and then you's still need to run one of those hard water nute solutions like GH Micro for hard water. And yes, let it sit for at least 24 hours with bubbling it withe bubble wands to evaporate the chlorine. I actually never need PH up or down anymore. I got my solution down pat and it's super stable, not to mention super simple. I start with RO water (20 ppm) use bcuzz bloom boster (it's very very ph stable) and GH 3 part. I tried GH florolicious bloom booster one time and it created a situation where my nutes were all over the board much like you're describing. This solution always puts me at 5.7 ph at 900ppm and does not fluxuate. I would not suggest florolicious but bcuzz is great.