Originally Posted by Aqua Jon
Sounds like Stealth is the way to go. I will be looking those up shortly. And good to know if Stealth isn't available local that there is a standard with that UL rating. Thanks! :)
Still wondering about those under-gravel heaters. For those of you who don't use them - any reason not to? If not i can try it out for all. Give some feedback. Add extra info to this site :)
Thanks again all
The "undergravel" heater I am thinking may be substrate heating, since you mention it in connection with plants. Several years ago the planted tank aquarists tossed around this then-new suggestion of improving plant growth with heating cables buried under the substrate (gravel, soil or sand as you choose). The idea is not common now because it frankly did not make much if any difference in plant growth, and I know of no authors today advocating substrate heating as beneficial enough to be necessary.
The idea behind it comes from nature: the substrate is normally slightly warmer than the water in rivers and streams. This causes currents as the water that percolates down into the substrate is warmed and then rises back up into the river/stream. This circulation of water ensures that nutrients in the water column will move around and continue to be brought into contact with the plant roots. Such circulation is normal in the aquarium without added substrate heating.
Another point is that this substrate heating is not sufficient to heat the aquarium. It is (when mentioned) always additional to normal aquarium water heating.
Diana Walstad mentions that substrate heating may prevent allelochemicals and other plant inhibitors from building up in the substrate. This is connected with allelopathy which is the release of chemical substances by some plants that can inhibit other plants from growing, a sort of plant chemical warfare
. That is quite another subject.