Filtering gasoline

I have a large fuel tank …350 gallons.  Of course, the fuel at the bottom is pretty dirty.  How can I effectively filter it? There is no pump. I siphon the gas out.

And yes, otherwise the gas is still good.

The challenge is to find a filter that won't dissolve in gasoline, won't have a spark/static risk, and won't leave a trail of new and different crud in your tank.

How much do you siphon at a time, and how fast? How large/small is the crud?

I recall that camping stores used to sell funnels for white gas (Coleman fuel or generic equivalent) used in liquid fuel camping stoves. It was a plastic unit with a superfine brass mesh screen. The large ones could handle the flow from a siphon setup. (Looking online, I see lots of funnels  with screens built for this purpose.)

I also think you could install a large inline fuel filter. But these are designed for the substantial vacuum "pull" of an engine rather than slight pressure differential of a gravity system; getting your siphon flow established might be a hassle.

Luckily only the gas near the bottom of a concern. As long as I draw from higher up, things are ok. But, it seems like a good time to draw it down and clean it out.  I normally don’t take out more than 15 gallons at a time….usually less.

To be clear, the filter doesn’t have to be in the siphon line.  I will accept any approach that results in cleaner gasoline as I approach the bottom of the tank.

For lack of a better suggestion, I am going to try to filter it through a coffee filter in a funnel.   Hopefully that will lighten the color a little.  I notice that a filtering system is available through Amazon in the $50 range.  Of course, that drives up the price of gas even if it does work.

figuring you have over $1000 worth of gas its probably a wise investment to get an inexpensive hand pump and a goldenrod filter inline after the pump and before the hose. or you might get an inexpensive 12 volt gas pump and put a small canister filter inline with 3/8" gas hose.
using a funnel and coffee filter might work but the fumes along that could probably gag a maggot. I dont take chances with dangerous stuff I would only use pump, hose and filter that is designed to handle gasoline. I am currently dealing with 10's of gallons of bad gas in old machinery and fortunately I know someone who has a waste oil workshop heater and he puts it to good use. I wish I had your problem of 300 plus gallons of good gas. on one machine ive been using compressed air through the tank fill hole and pushing it out through a hose into 5 gallon containers.

Hi Bruce,

I came upon the tank pretty cheap. Maybe $50 or so. Anyway I buy at $3 a gal or less and use it as the price goes past $4.50.  For the most part, the gas is in good condition (I treat with PRI-G).  As you observed, it is that 10 or 20 gal at the bottom that looks darker than I would like.  I do have a hand pump, but I am a creature of old habits.  

As I write this, I am wondering if the dark gas might have more PRI-G that settled near the bottom.

So, since you said you don't like the dark look of the fuel at the bottom, I'm guessing it is a translucent plastic tank, like an IBC?

I'd try to take some samples from near the bottom and from at the bottom. Put those into clear jars so you can better assess what's going on. Like you said it could be a different ratio of your stabilizer, especially if you are overdosing it, or at the bottom there could be sediment or water.
You could also try "magnet fishing" in the tank to see if the darkness is rust, a magnet would get fuzzy with rust particles if they were present.

I've had success with "cleaning" tiny amounts from outdoor power equipment and jerry cans that have gotten water or dirt in them. Drain into a clear container, let it sit. Often the dirt gets caught up in the water, so when I decant the fuel I just leave the blob of water behind. I had a can of diesel with a half-pint of fuel, a half-pint of water, and some debris, I swished it out of the can into a jar where it was a milky mess. Wait a week, and the fuel is perfectly clear with a blob of dirty water in the corner of the jar.

Hi Kenneth,

It is a steel tank.  I can judge from how deep I put the hose when I take gas out.  I did put some gas from the bottom in a gas can to let it settle for a few days. I suppose it is time to check.