Last week of flower . . . high PH

I'm in the last week to 10 days of flower and in the last few days my PH is running at 7.0 or higher. I am putting in 2-3x as much PH Down as I have previously and it doesn't drop the PH much at all. I can eventually get it to 6.0 but within 24hrs it is back to 7.

I have been using Drip Clean to reduce salt build up and I'm using the entire House & Garden line (Aqua Flakes) and the plants look great!!!

ANY THOUGHTS???

PS. I just did a reservoir change yesterday and filled with fresh water & mutes. There is no noticeable salt build up.

are you going to flush the last week or two? although their is some debate on whether flushing does anything to enhance the final quality of the product.

what do your trichomes look like?

what strain are you growing? Indica? Sativa? or a lil of each?

how big is your rez? your grow space?

whats your lighting like?

what type of water are you using? tap? R/O? etc..etc.

I haven't decided on flushing yet.

Trichomes are clear, Nirvana Swiss Cheese, 25 gal reservoir using tap water in a 6x6 space running 2000w lights & CO2

6 plants RDWC setup

Anyone? . . .