Welp. It's not as easy as adding 8 days of your recent loss worth. Chlorine burns off as a % and the added loss becomes real noticeable once you're well above target range.
Can you cover it with a tarp ? That would help a whole bunch. I'd buy a Costco roll of seran/cling wrap and use (the whole roll) as a belt to hold the tarp on. It would hold for 8 days and maybe even the winter. Lol.
Your FC is safe to slam level (24). I'd tarp, slam, and toss a couple of pucks in a floater to help add some slow release FC. If you can't do the tarp, then slam and floater.