ALL suggestions needed. My sanity depends on it...

So I've been having some issues in mainly my flower room. It is occurring more and more in both rooms now but the flower room is to the point of out.. of.. control..... It's frustrating, it's concerning, it's going to drive me completely fucking insane. So ANY suggestions whatsoever are greatly appreciated.
It started when one of my HPS lights in my flower room went out. I had to take it down for 3 days to be repaired, which was no big deal, as there were only 9 plants in the room at the time. After the light got hooked back up, my nightmare began...

The pH in EVERY bucket that is in the room longer than a week spikes to below 4.0 within 10-12 hours. In some cases within 3-5 hours. It is going to drive me to complete insanity, I'm sure of this.
I'm running DWC in 5 gallon buckets. There are 15 in flower. 4 are on day 50, 5 are on day 29, and 6 are on day 8. And 10 in veg. 2 moms and 8 on day 8 in the bucket. Then there are 8 more clones but those are irrelevant. The two strains are Aurora Indica and Quasimoto. They are running on a 112 watt air industrial pump with individual lines to each bucket. This comes out to just under 4.5 watts per bucket. More than sufficient.
The nutrients are General Hydroponics, Lucas Formula. I use Cal Mag all throughout and Phosphoload the last two weeks before flush. I have FloraKleen for the stubborn girls who lock up. Much faster than using just water.
In veg there is 1x1000w MH, and bloom is 2x1000w HPS. Clones go in rockwool, and after rooted into 6" net pots with hydroton.
I can't imagine the light having anything to do with it and I've never had a problem like this before. I use all filtered water and haven't changed anything in quite some time.

If there is ANY suggestions or comments please please PLEASE chime in.
My sanity depends on it...
Thanks.

iv had a similar problem b4, i had a recirculating dripper system, what i did was when i changed the tank i used ph up to make quite a strong alkaline mix my ph went to about 8.5 initially then the next day i checked it and it was 6 and stayed at 6. you just need to use a strong alkaline mix so neutralise the excess acidity

For some reason that doesn't work either. If i set it out of range it stays out of range. Only if it's set correctly does it then go out of range. You can clearly see where the frustration starts to set in haha

Have you drained the whole thing and refilled with fresh ph'd water?

did you recently change your air lines or stones?

Originally no hoses or stones were new. Since the issue I've changed everything from the stones and lines to the buckets and syringes I use for nutes and such. Water change was the absolute first thing I did when I noticed the issue