pH stays down - needs constant adjustment

Hello,

Beginning about the middle of week 4 in flower, my pH has started to go below 5.0. I check the pH in the a.m. and it will be around 4.8...I add a small amount of pH up and a lot of fresh water, get it back to about 5.8, the leave it alone for the rest of the day.

The next day, I will check pH and it is always back down to ~ 4.8. I started to ease off on the nutes (now in the middle of week 6) and I am still getting pH droppage. I went from 1100 ppm's to 900 in this 2 week span and I have changed my rez once a week during the entire grow cycle.

On the other hand, the plants are looking great!!! I mean, they are lush green, show no signs of deficiencies/burns, and are filling out quite nicely

So I guess my question is, is this droppage a bad thing? I don't mind having to top off the rez with fresh water everyday to get it back in balance, but is it normal? Does anyone else have a similar problem? I figured it was just cause the plants are drinking/eating like crazy at this point with all the flowers blooming and it's lifecycle coming to an end...Any feedback is appreciated!!!

Thanks...

My ph normaly goes up, so I add ph down almost every day.. That is unless I add fert (fox farm which is ph balanced)....Maybe your nutes are breaking down slowly and slowly lowering your ph...Ive heard that a .8 flux in either direction is not considered to be a big deal... Have you double checked your ph meter?