Winter Pool Covers: Water, Ice and Snow
How to remove rain water from a pool cover?
Small electric submersible pumps are used to pump water off of the pool cover. Large sump pumps can damage a pool cover, for this reason small pool cover pumps are recommended. Connect the cover pump to a length of garden hose, and plug the cord into an outdoor electric outlet. You can use an extension cord if needed.
Cover pumps are available in automatic and manual. Auto cover pumps turn themselves on and off as needed, but manual cover pumps are either on or off only. Automatic cover pumps will turn on when the water level reaches 1/4" deep. Manual cover pumps should be plugged in when water depth approaches 1 inch, and shut off after pumping, to prevent pump overheating and failure.
How often should I pump water off a winter pool cover?
More than an inch of rain water or snow melt on a solid pool cover can begin to stress the seams and 2-4 inches of water can begin to pull the pool cover into the pool. In freezing climates, several inches of frozen water on top of the cover can damage the cover and possibly the pool.
Another reason to keep your pool cover nearly dry is that water on the cover attracts worms, and worms attract birds, who can poke holes in your pool cover with sharp beaks and claws.
For aboveground pools, a small amount of water on the cover can help hold down the cover in high winds, although using wall bags and air pillows is a better solution.
Pump off solid pool covers when the rain water on the cover is over 1 inch deep. How often that is depends on rain and snow totals, but about 1-2x per month in most cases.
Setting up a pool cover pump
Cover pumps should be placed and removed carefully, to avoid snagging the pool cover. Some pool owners set it on an upside down Frisbee, and push it out to the middle with the pool brush. This also helps avoid pumping out pool water through small holes that may be in the cover, close to where the pump is placed. Connect a garden hose to the pump to carry the water away from the pool, and plug the pump into an outdoor electrical outlet.
Setting up a pool cover siphon
Siphoning pool water is not recommended as the primary cover dewatering method. It's ineffective because it won't pump off all of the water, and it can be hard to start a siphon, unless you already have way too much water on the cover. However, if you find yourself without a cover pump and you have a small hillside near the pool, or a point that is 3-4 feet lower than the pool, you can siphon off water from your pool cover.
Use a garden hose, or a pool vacuum hose, and fill the hose completely full of water, either from a garden hose or by pushing it hand over hand into the water until it no longer floats above the water. Attach a heavy but smooth and soft item to one end of the hose with duct tape to weigh it down. On the other end of the hose (now full of water), cap the end with your hand or thumb, and quickly move the hose to the location 3-4 feet below the pool water surface, keeping the hose close to the ground as you move it. Release your thumb from the end of the hose and water should begin to flow. Adjust the cover as needed to help pool the water in the area of your suction hose.
Pool cover pump maintenance
Heavy leaves and debris can clog a cover pump. Use a pool leaf rake net to scoop leaves and sticks from the pool cover regularly. Leaf Nets or Leaf Catchers, spread over the pool cover, allow you to remove all leaves in one fast and easy motion. For very heavy leaves, the pump can be placed inside of a larger strainer basket (such as B-37 or B-152), to help prevent cover pump clogging.
Check on your pool cover pump during the off-season, to be sure that it's operating correctly, and is positioned properly. Tightening the pool cover, or pulling out slack or wrinkles, helps collect the water more uniformly, for faster pumping and easier leaf removal.
Ice on the pool cover
In the northern half of the country, pools freeze solid, to a depth of 4-12", depending on how far north you are. Not much you can do about the pool freezing under the cover, but as for the rainwater on top of the cover, it's best to remove water before it freezes solid. Why? Ice expands 9% as it freezes, and puts pressure on the pool cover, and as the ice sheet begins to melt and shift, sharp edges of the ice sheet can damage a pool cover.
When the pool cover turns to a solid sheet of ice, unplug the pump until the ice begins to melt. Running the pump while it's encased in ice (and not pumping water) can cause overheating and failure, or it may trip a GFCI breaker if the pump impeller is frozen. If your cover pump is buried in ice, just leave it alone until the ice sheet begins to thaw from underneath, you can plug-in the pump again, checking the hose to be sure it's pumping water
Snow on the pool cover
Snow on a solid pool cover is not a problem. Winter pool covers are designed to float on the pool water, so even several feet of snow on a pool cover is no problem in most cases. Snow will melt eventually, and as it does, the cover pump is used to pump off the snowmelt water. Do not attempt to remove snow from the pool cover; it's unnecessary and could damage the pool cover.