IMHO, the borates make the polyquat unnecessary. Your choice--expensive polyquat weekly or relatively cheap borax and acid once a year (and $10 for a tube of borate test strips!)
Borates do not have an effect on FC, make the water sparkle (not joking about this), help stabilize pH, reduce chlorine usage in many cases, and will lead to world peace!

Only time I ever break out the polyquat anymore is when I am doing AA for stains (and have not had to do that in a few years since I started keeping my CH higher in my fiberglass pool.)


BTW, I have to share a good laugh I just had (a bit off topic). I was browsing another forum and saw someone who is held out to be an 'expert' trying to explain where cobalt spots come from in a fiberglass pool. He was so far off the money it was sad. If he had just googled it he would have had correct info. Sad, no?