Heating for fish

I was wondering how you guys keep your fish tanks warm during the winter months.

i have a 1,000 gallon tank for my tilapia in the small green house. the weather here in Ohio has started to be in the 20's most nights.

I have a recirculating solar system that works reasonably well during sunny periods, but could use some improvement.

i also have a portable hot water heater that runs off a portable propane tank.  in the current weather conditions. (no sun for over a week) it's using a 20lb tank in about a week.

what are other people using .

regards Phil

I got nothing to share, but I admire your setup!
Putting the solar water heater outside along your knee wall is great.
What tempature do you keep the tank at?
How warm is the air in the greenhouse?

Hi William.
I have 2 tanks in the green house 1 is about 1000 gallons and the other aprox 800.
the larger tank has Tilapia which needs the heat in this weather, and the smaller tank has trout which like the cooler water.
i keep the Tilapia between 70 - 80 degrees and the green house temp when i check in the mornings is 50+ this is with the outside temps in the low 20F
I only run the Propane for a few hours each morning as the temp drops over night to either high 60's or low 70's.
I run the propane until i get it to the mid 70's and when if the sun comes out i use the Solar to raise the temp as high as I can get.
so far the fish look to be happy..

Regards Phil

A 5 gallon tank per week could be considered pretty darn  cheap depending what you get out of it.
Tilapia eat veg, but trout prefer insects,I think.
Any luck growing your own feed?
50 or better is plenty good for plants, I see some vines in the photo.

The vine you see growing across the back there is Water Spinach. i planted around 100 in there for my wife's garden in the summer. i left a couple in the floating trays once she had replanted everything she wanted and they took off around the pond.
I have several floating seed start trays that I'll be using to plant tomatoes and different peppers starting around February (each tray has over 200 plants), the plan is to get them started in the fish tanks, once large enough they can be potted and put on the shelves in the green house. then sold at the front of the house for a couple of $ each. I'm not trying to retire on this endeavor, just hoping it can cover its own running costs.

Regards Phil

Just a couple ideas that I am using for my 100 gallon pond (water trough) inside my small greenhouse.  I have an appropriately sized fish tank water heater inside the tank to stabilize the water temp where it needs to be.  For the extra cold nights (high desert in southern Utah may dip to about 20 on occasion and sometimes lower if a storm comes though) I have a heat tape, designed to keep pipes from freezing, wrapped around the outside bottom of the tank and about 6" of insulation over top the heat tape.  The thermostat for the heat tape is halfway out of the insulation so it comes on more often when the air is extra cold but it wont stay on nonstop and cook the fish.  I used old plywood to build a box around everything to reduce airflow.

I am guessing they don't make a fish tank style heater large enough for 1000 gallons but you may be able to use a couple 500 gallon models or three 300 gallon models depending on what is available.

Well, first thing that comes to mind is using something like heat accumulators. Design can be different: from (amature build) bricks cowper that are heated during day and return heat and up to tank with paraffin that melts during day and solidifies at night.
Second thing would be insulating fish tanks.