Actually Enrico, your CYA is not bad. I was at 80 back in April, and I’m down to 60 now from oxidation. You’ll probably finish out the summer at 60, which is fine for the Desert. I wouldn’t bother with the water change unless it bothers you that much. If you do do it, you want daytime temperatures to be under 80 so your plaster will be safe to be exposed. So Dec-Feb is the best time for the drain/refill. Keep in mind though, depending on what town you’re in, check with your water company to see when they set sewer rates for the year. I’m over in Chandler and they just have a flat rate for sewer, so no worries if you live there.
So your numbers are all good, so then the next culprit is like you said, the cartridges are most likely shot. We have the same size pool, and I have a Hayward with 4 cartridges as well, and my pool was back to normal the next day. And I didn’t run my pump anywhere near as long as you did.
I’ve only cleaned my filters once since new (nov) and they really didn’t need it then. (I was just curious)
Do you use hairnets on your skimmer basket? If not, you really should as it helps with the dust we have here. Also I noticed you don’t have a canister filter on your Kreepy Krauly hose, you should look into one of those as well. Everything that it sucks up, goes straight to your cartridges. The more you can grab before it gets there, the less you have to tear that puppy apart to clean it.
