Water Gardening: winter covers on ponds ?, 1 by gardenkat

gardenkat wrote:
I got these directions from Steve C. through another forum. ( I hope it's OK to post this here.) I used the 1A modification to make it easier to change the lightbulb. The bulb in mine burns out in January or February and has to be replaced but by then the base is frozen into the ice. The modification makes it easy to get to the bulb to change it when necessary.

POND DE-ICER
Parts needed: 1: 4 PVC 90 deg. elbows ( 2" to 4")
2: 4 ft. of PVC pipe ( 2" to 4" )
3: 1- 12" plastic flower pot (12" dia. )
( 12" to 14" tall)
4: 1- weatherproof lamp holder
(with cord attached)
5: 1- 75-watt light bulb
6: a few sheet metal screws
Mount the lamp holder to the inside of the flowerpot with sheet metal screws and run the cord out of one of the side holes in the pot (the pot I used is thin and had 4 holes around the bottom)
Cut and glue four pieces of PVC pipe so the ring you make has the same inside diameter as the outside of the flower pot (try before gluing). Attach the flowerpot to the PVC ring with 4 sheet metal screws (use a small dab of caulking on each screw hole.

As an option, you can fill the pipes with spray foam like (Great Stuff) to make sure the whole thing never sinks, although I haven't had a problem. Make sure the cord on the lamp holder is long enough to be outside of the pond. And please make sure you have this plugged into a GFCI receptacle.
I think the holes in the bottom of the pot are important. First, they let any (bad) gasses escape if this is the only open hole in your pond and second, they won't let the plastic pot
get too hot yet still provide enough heat to melt any ice.
I'm using a 75 watt light bulb but I'm sure you can go all the way up to 150 watts if you
had to but 120 watts should be more than enough no matter where you live.

NOTE: 1A shows a modification to make it easier to change the light bulb should it ever burn out and the base is frozen in the ice.