I am not quite sure what to do - I could bring Zop in for the winter, but my tank wold be overstocked and Val nibbled his fins when I brought him inside to do maintanence on the pond. The heater I bought (and returned) said not to be used where exposed to weather. The pond heaters are HUGE and expensive.

What kind of a heater is small enough for ~25 gallons, fish-safe, and okay outside in freezing conditions?

In anything raised and exposed to the cold, it will be easier for it to freeze. Can you not bring the barrel inside into a cool room somewhere so it can winter with the fish in it?

I have searched high and low for a heater that will work for an outside tub/barrel; can't find any. Some are using acquarium heaters and then covering the tub with styrafoam to hold the heat in. I have not tried this because I'm not sure it will work in my climate.

I agree with Sandy, I think if you can somehow bring your fish in for the winter it's best.

I CAN bring my fish in - though not the barrel - but right now, all I have is a 10 gal. I may be getting a 33 gallon, but that may or may not fall through. Also, I'm worried about the roots of my lily freezing solid.

Would putting in a two-litre bottle of warm water every day help any?

Where do you live? How cold will it get?

From dec through feb, it could be -2 to -10 © at night.

Yikes!

Yes, they have to come inside. What do you do with the plants?

Maybe a Bird Bath de-icer will work. Check this out:
http://www.watergarden.org/s.nl/it.A/id.78...sc=2&category=7

You can write an email to these folks at The Water Garden to ask them advice.

Well, it probably won't - those are just the possibilities. And it's rarely below zero during the daytime. Isn't 150 watts too much for 25 gallons?

I know that the nearby water plant place leaves their barrels out & they don't freeze all the way through - doubt they care much about their fish, though. Do you think any of the aquarium heaters could be safely used? I don't care about replacement so much as not electricuting Zop/Myself.

I would not recommend using a heater designed for indoor use.

The birdbath heater is thermostatically controlled, and probably safe - or it would kill the birds. There's a page on the website for submitting questions. Can't hurt to ask them.

If the barrel is located under a shelter, like a porch you might be safe to use acquarium heaters. If it's going to be out in the direct weather then I woudn't. I have tried using acquarium heaters in my porch pond. They never heat the water adequately. The heat escapes. This is why some use the styrafoam tops. I have even contacted TetraTec regarding a heater for outdoor containers and they know of no heater for outdoor use. I expressed a need for one. The deicers are only that, they will keep ice from freezing the top completely, but will not heat the water.