So i recently set up a above ground pool as a koi pond my plan is to house some temesnsis peacock bass with them but it gets to cold in the winter on some nights. Ive been looking into tankless water heaters. Since it costs so much to constantly run those i would be setting it up on a timer to run at night. To keep costs lower ive been looking at 1.5kw heaters. I would like to set up a permenent soulution for the winters so i can house other tropical fish. I was just wondering what anyone with experince thinks of my idea.