We have just come out with heating cables. We have three sets but they are not yet available. They are low voltage sets but only heat the substrate, no temp controller is required, a standard tube heater is required to heat the water.
Set 7028.20 20W up to 45gal- $93.70
Set 7028.40 40W up to 90gal- $112.10
Set 7028.80 80W up to 180gal- $153.83