Ive been using four 300 watt aquarium heaters in my static tank for the last 2 winters!
I have not missed 1 day due to freezing weather conditions
I have one concern tho, legionnaires disease!
Certain conditions increase the risk from legionella:
a suitable temperature for growth, 20 to 45oC
a source of nutrients for the organism, eg sludge, scale, rust, algae, and other organic matter.
a way of creating and spreading breathable droplets, eg the aerosol created by a cooling tower or spa pool.
What do you think guys? are we at risk heating water this way?
Regards
Simon