1000 gallon poly tank.. heater question

SO I need an idea of how I can heat 600 gallons of water to about 75 degrees. in this poly tank.. is there such a heater..and where can i get one..

Is this a permanant or a temporary or 'mobile' installation?A hot water boiler with a 'side arm' would work well,but that not very portable.

If it's outside - Paint it Black ???

Its only a temp set up.. I would fill on a thurs night. need to get temp up by Sat. then empty on sunday. This is outside. Dont know what the temp will be in April in Nebraska then. Its been 60-70 during days 40-50 nights..

Years ago I built a portable tank heater by mounting a water tank element on a pipe setup. Wires were inside the pipe and protected from the water. Looked something like this. The collar that held the element was made by drilling a hole in a end cap and it seems like I had to make a collar/bushing to go inside and take up the slack between it and the matching pipe fitting.

As you fill it let a salamander heater blow on it not close enough to melt the tank though.

RV water heater and a circulation pump?

It requires 1 btu to heat 1 lb of water 1 degree F. 600 gallons of water weighs 5000 lbs, therefore 5000 btus are required to raise the temperature of the tank 1 degree. For example if the water comes out of your well at 50 degrees, to heat the tank to 75 degrees would require 125,000 btus (5000 x 25).

If electricity is available, 1000 watts for 1 hour is 3410 btus. A stock tank heater is typically 1500 watts and would require 24.4 hours [125,000 / (1.5 x 3410)] to heat the tank from 50 to 75 degrees. This assumes no heat loss so you would want to up size the heater (use two stock tank heaters) to account for a cold windy day. Also keeping the tank covered until use would reduce the heat loss.

If electricity is not available, propane contains approximately 90,000 btu per gallon. Assuming a heater efficiency of 70% approximately 2 gallons [125,000 / (90,000 x 0.7)] of propane are required to deliver the 125,000 btus to the water. If the propane heater is rated at 10,000 btu/hr it would require 12.5 hours (125,000 / 10,000) to heat the water to 75 degrees, again assuming no heat loss. A standard 20 lb propane cylinder contains a little less than 5 gallons of propane. Again I would keep the tank covered to prevent/minimize heat loss.

Hopefully this helps in selecting or fabricating your heater.