I use a Rule fully automatic pool cover drain pump. I leave it on my automatic cover all winter long. The pump automatically turns on and checks for water approx. every 2-1/2 minutes. If water is found, it will run or as long as water is present, then it shuts off and returns to its 2-1/2 minute "check". The pump is equipped with a protective circuit that prevents damage in the event it gets imbedded in ice or the impeller becomes jammed with debris. Its a great pump and wouldn't be without it. I bought it online. In fact, the first one I bought died within the warranty period (three years) and they sent me a brand new one, no questions asked.
I can co-sign everything in the post above, including the no-hassle warranty replacement. The newer replacement models (for several years now) have a domed top, as opposed to flat, and are better sealed so hopefully they won't need it. This is the only pump I have seen that can survive being frozen and thawed. Here in NJ we can go from rain to freeze and back again many times in the course of a winter. The Rule can handle it. Mine stays out all winter.
Another one to consider is the Little Giant (model# 5-APCP). I've gone thru 2 in 11 years. We have some cold hard winters here in Indiana and I leave it out all winter. The only reason the one went out was my lack of preventative maintenance on it. We have many leaves that get on the cover over the winter season and I didn't clean them out like I should have. The one I have now is on year 3 and it's running strong.
You may find mixed reviews from various sites that sell it but I'd buy another if this one quits.
Placement is pretty self explanatory. Just wait till you get a little rain and you'll soon see where it needs to be placed. When mine went out I wasn't aware till the following day after a hard rain and I had somewhere in the neighborhood of 100-200 gallon on my cover. I'm shocked it didn't bust my straps/springs that hold it down.
I am looking for a solid cover pump as well. I have looked up the one listed above, the Rule, and it is discontinued per their website. Any other recommendations? I live in Illinois and last few winters have been brutal. First year with a solid cover, we have always had mesh. Liked it but was sick of it taking 2 weeks or more to clear up water when opened. Also ours got holes in it from mice eating thru it last summer. Any suggestions are appreciated.