This is a simple pool cover pump - which uses gravity to siphon off water or melted snow off the pool cover, without a powered pump.

For those of us that live in northern climates, a cover pump comes in handy to drain water, or melted snow/ice off a pool cover. Unfortunately, electric pumps too often die if they are left on the cover and get “iced in”. For years I had used my dead pump (which I cut the electrical cord off of) as a gravity feed pump, by connecting a 50 foot hose to the hose connection on the pump. The plastic finally cracked, so this is a simple replacement.

This type of gravity feed pump requires that there be no air leaks at the top of the box, at the hose connection, and in the hose itself (until the end of the hose is below the height of the water that you are trying to remove). On one build plate I have combined the hose connection (taken from bdwilson - Fibro Pool Submersible Pump… model) and combined it, a cover, and the box to ensure no air leaks. This may be acceptable if using PLA - however if using ASA (suggested for UV resistance), then I was only successful in separating the hose connection and end cover from the box (otherwise corners curled and destroyed the print). Also, I was only successful in printing ASA on the textured PEI plate, with the addition of bed glue.

For assembly:

1) In order to ensure an air-tight seal between the box and the cover with the hose connection, I first applied 2 part epoxy liberally around the box joint (the side without the holes).

2) After dried, I then applied from the inside a bead of DAP UltraClear - which I consider better than silicone for reliable adhesion.

3) Fill box full of small clean rocks (to ensure adequate weight into the cover to provide a low spot for the water to collect in). Just be sure that the neck of the hose connection is not choked with a rock.

4) Spot epoxy the bottom cover into the joint side with the holes (I did the 4 corners and a spot in the middle of the long sides).

For use:

1. Connect a drain hose with a good washer to the hose connection (don't over-torque - after all, it is a 3D printed part)
2. Place the box into an area on the pool cover - so that all of the holes are below water (otherwise the vacuum will be lost)
3. Carefully pull enough of a vacuum on the drain end of the hose to get water to start flowing over the pool rim, and wait for the water to start rushing out the opposite end.

Yes, for novices this is typically accomplished by sucking on the drain side of the hose (I use my hand between the hose end and my mouth) - but only do this when the hose is dry to begin with - or you won't like the result! Once the hose has been primed, I find there is always enough water left in a 50 foot hose to reestablish a vacuum if you first submerge the box into an area of water, and then just lift the hose about 3 to 4 feet above the ground and move quickly from the pool side to the drain end of the hose.