Hey Mate,
Just want to add,
may you wanna have a look at this:
https://www.agrobest.com.au/news/How-Soil-pH-affects-availability-of-plant-nutrients-7.htm
Helped a lot.
You know that your soil can easily puffer the pH of 5.2 for a short periid of time.
I would adjust water pH through the whole flower on 6, and I would stop checking your run off when growing on soil. I think would just consternate.
Good luck and happy trails for the rest of the way 🤞
Servus✌️
OimRausch