I will be out of town for about ten days and need to "close" my 12000 IG vinyl-liner pool while I'm gone (actually I have no choice). I was thinking of simply turning off the pump, putting on my solid winter cover and leaving. My usual numbers are: ph 7.8, alk 110, CYA 30, Total chorine 5, never any combined chlorine. Water temp has been between 70-80 past two weeks, outdoor temps between 75-90 high and 55-65 low.

Does anyone have any experience on what I should expect when I return? This seems similar to closing in the fall, except I won't be blowing out the pipes like I do in the winter. Usually, in the spring, we can swim within 72 hours of opening, with a little debris in the water but no algae problems visible or any difficulty maintaining a chlorine level.

Should I keep a "shock" chlorine level for a few days before leaving? Should I raise my CYA level? I have been adding 60% poly algacide every week for the past month or so and have no apparent water problems now.

Thanks for any advice or experience you can share.