I have built a system that I believe contains about 600 gal of water. My grow bed contains 3 tons of gravel and is 4*16' and a dwc bed 4*8'.
My greenhouse is 24*32 and single ply plastic.
I live in kingsport TN where out fall and winter is rather mild. 2-3 weeks in Feb will stay below freezing.
My water temp has been swinging from 50-60 deg .
I have 40 +/- goldfish between 4-8"
My question is two fold.
Is it necessary to heat the water. If so, does anyone have a reasonable idea the cost to heat with electric heaters?
I would prefer to select crops that are cold tolerant and not heat the system.
Any thoughts or advise would be great.
Jeremiah has lots of info on cold weather aquaponics: https://www.frostyfish.com/
I think it will be necessary to heat the water. Or at least to be able to. Not just for the fish but also for the plant, root, and beneficial micro-organisms. temperature. The coldest months could probably require about 3 to 4 watts per gallon of water to heat. So 4* 600 = about 2.4 kW/h. I looked and found that this time last year in the Kingsport area the residential rate was just over 8 cents per kW/h. or $1.92 *2.4 = $4.60 per day max. during prolonged low extremes.
It is very important to maintain proper flow rates along with high and low temperature limits so that swings are avoided.
I hope this helps.
I have a 600 gallon system in a 8'x22' greenhouse with double layer plastic and spent $100 a month last year just to heat the water (1000watt heater running 24/7 and barely holding 67F). I used low tunnels around my grow beds rotating on/off of 3- 400watt lights. This year I'm going to try heating the greenhouse with wood and propane combination to 50-60F and the tank to 65F with the tank heater. I also insulated non-essential sides (east and north walls, lower 4' of other walls, and roof over fish tank) and added insulation to the fish tank. I don't think it will cost any more to do this but I'll find out. But I'm in Michigan and it was reeeeeal cold last year. So far this year I haven't needed any of the improvements lol.