I came across this diagramn today
reminded me of when i first started keeping fish
we had metal framed tanks standing on asbestos an heated by gas jets, or parafin heaters
. in tank immersion heaters were available but we didnt always have enough the electicity connections

( and no !! I didnt live n a hole in the ground with a tarpaulin for a roof.)

couldnt afford tarpaulin

hey the way electric prices are going I may be looking your help!

got a link to the diagram?

i've used gas and parrafin heaters as well as electric heaters to keep temps up over winter onto of in tank ones and still not found the balance to make things affordable

At present i am planning to shut down fishroom next winter, let my pond koi and goldies use my planted/lit tanks and keep my filters going, obviously i will keep a select few bettas in the house but i would love to find a nice solution to especially heating the chilled well water and the room over winter periods now we are getting below -5 temps!

I know this is an old thread but does anyone use solar panels for heating?