For various reasons, I have to store my BD outside.  I do, however, mix with kerosene and anti-gel when I add it to the storage tank in the winter.  But I only mix it for what I expect to encounter, not what can be the coldest in my area.  I am worried about needing fuel during a frigid (for the area) cold snap.

Has anyone used a submersion heater in their storage tanks, and does anyone have any guidelines for sizing such a heater?  I can get one on ebay for about $46 shipped that is 1000 watt.  My tank is a 300 gal IBC plastic tote type.

Well, since no one had any input on this, I picked one and tried it.  Luckily, it worked well for me.

Here is what I ended up buying.  I got it through ebay for less than $50 delivered.

Allied Precision Rapid Water Warmer Model 742G.  It is a 1000 watt heater that runs on 120V.

Now, as with probably all immersion heaters, this had the warning "DO NOT HEAT ANY FLAMMABLE LIQUID" with the paperwork, and as such, I am saying I did this, not that anyone else should, and I take no responsibility for anyone ignoring the directions.

I had about 225 gallons of fuel (B66/K33/Addative1) in a 330 gallon tote.  There was about 5 inches of settled out solid fuel in the bottom of the tank.  Lowering the heater through the 6 inch openning on top of the tote, I tied the heater up so that the heating element would be submerged, but not the handle or cord.  In about 50 degree weather with sun on the tote, it took about 8 hours to liquify all the fuel.  I also, at least once an hour and sometimes more, reached in, grabbed the handle, and stirred the fuel for about a minute.  Without stirring, it would have taken a lot longer to melt the fuel with this method.

Hi All,     I am responding to you about using an electric emersion heater in a poy tank  If you check with the manufactures of those types of tanks you will find that most of them don"t stand behind their tanks if you use heating elements in them.They say their tank is only rated at 70 degrees to 100 degrees F.  and if you use a heat source in the tank it will soften the tank walls and the tank looses it"s strength.Also there are issues with permeration  through the tank walls.If you use a cross linked polyethylene tank of 1.9 specific   gravity or higher you can get by with a little more heat in the tank,,but the manufactures still will not stand behind their tanks with heating elements in them. Be careful,and I would recommend steel tanks or stainless steel for your biodiesel fuel processing and storage needs if you are putting heat in your tanks.. Thanks,,Duff Streeter  www.michiganbiofuel.com

With your warning, let me just add something...  The heater was no where near the sides of the tank, and the fuel got up to maybe 50 degrees after the 8 hours of cooking.

I am glad everything went well for you using your electric heating element. Just be careful as poly, tanks well not take a lot of heat untill their sides weaken. We don"t want anyone getting hurt or any fires relating to this type of tank heating system.It could be very bad for you as well as this  new exciting industry.The Gov. would like to clamp down on us small to medium sized producers,so please be a little bit careful..    Thanks Duff  www.michiganbiofuel.com

Poly tanks can take a lot more heat then you think . I make my biodiesel in a cone bottom 110 gal poly tank . My first tank had a heating element through a bulkhead fitting in the side heated to 65c no problem . I even get my suppler to beef up parts to take the heat better .