Take a look. 20 FC at 50 CYA has less Hypochlorous Acid than tap water with 1 FC @ 0 CYASolid covers deteriorate faster and become more brittle from high levels of chlorine. If you’ve been maitaining proper chlorine levels, I dont see why you should have bacteria growing in the dark.
Even at our best attempts each season, some pools simply turn green and others don't. Owners do their best to increase the FC level al bit at closing, while others try the Polyquat 60 route. Still, some pools simply react differently than the year before. It's not an exact science, and pools in various parts of the country react much quicker than others. But owners do their best with the info provided. The cold water certainly helps which is why our moto is always, "Close late - open early". Covers of various types have their own pros & cons as well. If your pool is cleaar each spring, you must be doing something right - don't change it. But for many, the insurance of increased chlorine (or using Poly 60) at closing helps get them through those critical 4-5 months.I never SLAM my pool before closing and water was always clean at opening.
Yeah, I dont think SLAM is always a must at closing. Solid covers are expensive, if I can help it last a bit longer its a winI never raise my pool for closing. Make sure waters sparkling clear. Just add poly60 and close end of September. Always open to clear water in late April. I have a safety cover on my pool which allows fine sediment in. Three years ago we had an incredibly mild oct/nov, I was worried but the poly60 did it’s job thankfully.