Thanks! I didn't know it degraded that fast. Got some 12.5% yesterday that seems to work better. Added enough at 10pm to raise the level to 12 PPM again and this morning the FC was at 4PPM. So it seems to be getting better, I can see the drain on the bottom of the spa againIt's almost the end of August and that's 6 months. It's definitely weakened, possibly even half strength.
No biggie so long as you know about it, you just need to add more of it.
Keep us posted.
keep slamming 