Maybe a BIT expensive!

BIG-G

Goliath Tigerfish
MFK Member
Dec 12, 2005
3,856
4,654
179
NC
about how many degrees will you have to raise the temp? What are the air temps there at night and day?
 

Moneypit

Feeder Fish
MFK Member
Jan 29, 2012
78
2
0
Wa
Check into gas swimming pool heaters
It is not a good idea to use one of these unless it has a stainless steel heat exchanger, most swimming pool heaters have Cupronickel heat exchangers that are about 75% copper. These can lead to copper toxicity in your pond.
 

HackJob

Gambusia
MFK Member
Mar 8, 2011
280
1
18
NH
In Florida it would seem that a simple answer would be solar. I have seen solar heating down by using black tubing and leaving it out in the sun. If you run water through a black bladder during the day, it ought to warm it up, some fine tuning would be needed. I would not run it at night so you would need to time the pump to be on during day time. Off at night.

It may look ugly, but it's cheap.
 
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