Canuk Couple First Grow

I had a feeling I was overthinking the grow and now the plants have decided to mutiny. From picture guides, it looks like I have a potassium deficiency, but giving them straight P-K flowering nutes and not improving, I'm not sure if that was the case. My thermometer/hygrometer died when the humidity hit 95%+ earlier in its life so I'm not certain on the temperature range inside the tent. I have a bad feeling that it's getting much hotter than I want it to be in there. I have checked the plants for signs of pests but don't see any obvious signs. My solution to this is to flush them each with 3 gallons of pH'd water only. I normally feed them 0.5 gallon each from the shared 1gallon mix jug. That's always plenty of water to soak the plants thoroughly and cause runoff so I only water them once every 4-5 days. Is flush and early harvest my only hope of salvaging this?