Being a newbie to pools, I am looking for guidance on purchasing a cover for our 22 ft round ultra frame Intex pool. I have looked online, and honestly, there are too many choices. I am not looking to spend a lot (already had to buy a new liner after we took the pool down last year...mice ) but, I don't know what kind of cover for Northern Illinois winter/wind. I see covers that profess to be 8 or 10 year covers and the reviews are saying they last 1 or 2 years for around $40-60 and I see mesh covers...? Dumb question, is the purpose of the cover to keep debris out or to prevent rain/snow melt from entering the pool? Also, any suggestions for keeping the cover on would be welcome, there is no rail to ratchet under. I was planning on snugging the cover with the ratchet tie, then using the saran wrap. Thanks.