As a new pool owner, I understand some of your fustrations.
I had a few months where my FC levels were all over the place. The solution I found was to keep a close eye on the CYA levels. I thought my levels were good at 40-50, but I just couldn't keep the FC up....I was running at 80% on the SWG. Then I pushed the CYA up to 70-80 range, and it made all the difference. Now my FC stays at 4-6 easy at 30% output.
So, get a good test kit and keep checking the CYA levels. Also, when you do add CYA, the FC levels will drop like a rock for the next few days. Rather than run the SWG in boost mode, just throw in 1-2 average size jugs of cheap-o generic brand bleach (for a pool around 10-12K gallons). That will get your FC up to the 10+ range and save the life of your SWG.
good luck!
I also did the boric acid/borax additions. The water has a cool shine to it and I think it feels better (not as drying to your skin/hair) when you get out. pH does seem to sit around 7.5-7.8 range much eaiser with the borax [20 mule team] :-D