Cheap, Adaptable and Safe Seed Bed Warmer

This just popped into my head so I thought I would throw it out there for discussion.

Get yourself a bucket, a couple nipples, hose clamps, aquarium heater and garden hose.

install a nipple near bottom and one at least 2 fists from the top (on the side) attach hose and run in a zigzag pattern under your starter flats. Position the bucket so the top nipple is below the level of your flats, ensure the top of the bucket is above the level of the flats to avoid a flood.  This is important as the circulation of water is based on thermosyphon (heat gradient driven).

Fill and vent the line, you don't want air pockets in the line.

Drill\cut\whatever a hole in the lid for power cord. Place heater in bucket and tweak as necessary. Inhibit algae growth as needed... pennies, bleach, vinegar, etc.

Feedback requested.

I plan to build this in the coming days.

Interesting idea, will be interested in how it works for you

  What I have always used for my propagation beds is an old water bed heater.We are in the process of building a larger propagation table for the new propagation room James built.This will be built from recycled materials as is all of our projects, the table large enough to hold 10 to 12  flats, first layer is the actual water bed liner, next the heater itself,then another piece of the bed liner followed by a two inch layer of sand with a drip system laid in for easy maintenance.Then one more layer of plastic,to keep the sand bed moist.We will also have lights and a mister system  for this.
  My last system like this lasted me 13 years when I was running the greenhouse.Keep in mind we propagate thousands of plants through out the season.We can also use it through the winter for growing all types of greens. In the unheated room..