With all liquid fertilizers stored over the winter in very cold conditions. A spring agitation is important to mix the higher concentrated product at the bottom of the tank into the weaker concentrated product at the top of the tank. -20C and colder will cause water to freeze out of the solution to the top of the tank. Agitation with air has been the most efficient way to correct this situation. Any small air compressor coupled into the bottom valve of the tank and run for about 1 hour per 1000 gals in the tank will do the job. Always wait until the outside temperature is above freezing in the spring before doing this job.
Adapting a cam lock to accept air hose coupler