Biocide side effect - clogging?

Rick D · Feb 4, 2014

I had a bad case. I used a commercial grade biocide after getting contamination from jugging fuel in from gas stations. The contamination was obvious from the primary filter residue. I purchased a used large dual fuel filter from Minney's marine surplus, and employed a high pressue auto fuel pump I had to recirculate the fuel (basically a home-made polishing). I did so for about 40 hours total after a shock treatment of biocide. I used copper tubing for the pick up and return and to agitate the fuel in the tank. They were connected to fuel lines from an auto parts store and then to the fuel pump and filter. Seemed to work well and residue in the primary filter was greatly reduced although i have doubled the frequency of changes just to err on the side of caution.

BTW, there are those who advise what I did was a waste of time and the only lasting solution is to pull the tank and flush it. To your original question, a simple diesel additive like StaBil or ValvTeck or other which has a maintenance-level biocide should not result in a kill off and clogging. From your description, it does not appear you have a (large) problem. BTW, my knowledge is as a practitioner, not a professional, so this advice is worth what you paid for it.

thinwater · Feb 4, 2014

Rick D said:
I had a bad case. I used a commercial grade biocide after getting contamination from jugging fuel in from gas stations. The contamination was obvious from the primary filter residue. I purchased a used large dual fuel filter from Minney's marine surplus, and employed a high pressue auto fuel pump I had to recirculate the fuel (basically a home-made polishing). I did so for about 40 hours total after a shock treatment of biocide. I used copper tubing for the pick up and return and to agitate the fuel in the tank. They were connected to fuel lines from an auto parts store and then to the fuel pump and filter. Seemed to work well and residue in the primary filter was greatly reduced although i have doubled the frequency of changes just to err on the side of caution.

BTW, there are those who advise what I did was a waste of time and the only lasting solution is to pull the tank and flush it. To your original question, a simple diesel additive like StaBil or ValvTeck or other which has a maintenance-level biocide should not result in a kill off and clogging. From your description, it does not appear you have a (large) problem. BTW, my knowledge is as a practitioner, not a professional, so this advice is worth what you paid for it.

Stabil does not contain a biocide. That said, any product containing solvents can have so biocidal effect (Startron is has shown this in testing, though it is not a biocide per se), including a few % gasoline.

Having worked on both industrial scale systems (up to 1mm gallons) and boats, generally it is better make an access hole and clean it out. Removing the tank, of course, should not be needed.

Yeah, any time you kill bugs, the bodies have to go somewhere; there's no magic.

Tom J · Feb 4, 2014

Skipper said:
I don't know if I've got bugs in the diesel tank or not. Engine runs good; filters are good.

But I thought I might de-bug the tank anyway, just in case. Then, I started thinking: If I kill 'em all, they'll then be in the fuel, and clog up the filters, probably when I'm on the bay.

Is this true? What should I do to prevent stranding offshore? I guess carry spare filters, but seems there would be a different, proven process for safely de-bugging.

To prevent standing offshore, you could install a vacuum gauge on the primary filter and monitor it's condition. As the filter becomes clogged, the vacuum reading will increase into the yellow Zone, and then the red Zone.

Rick D · Feb 4, 2014

Thanks!

thinwater said:
Stabil does not contain a biocide. That said, any product containing solvents can have so biocidal effect (Startron is has shown this in testing, though it is not a biocide per se), including a few % gasoline.

Thanks. I could have sworn it did but I looked at the description and (as you know) it did not. Not to doubt you, just to shore up my memory.

Steve Dion · Feb 4, 2014

A cheap/safe option may be to drain the tank. Clean it out and refill with clean fuel. I would guess that this will cost less than $100 for the 30' boat.

Maine Sail · Feb 5, 2014

Easiest and least costly no-strand solution..

Drag needle vacuum gauge

10 or 30 mic on primary

Change when drag need moves away from "normal".....

Many years ago we did a delivery on a Down East style boat that had been used in the Chess as a floating condo. The fuel was in horrible shape but this was well before commercial tank cleaners existed as a business. The new owner stocked if for the delivery with a case of 2 micron Racor 900 series filters. This guy pretty much bought everything by the case but that is another story....

Long and short is we went through all ten 2 mic filters in 1/4 of the trip. We stopped and bought ten more 30 mic filters. We made it all the way to Maine, in 4-8 foot seas, on ONE 30 micron filter and the engine ran perfectly....

Anonymous 121765 · Feb 5, 2014

It's just my opinion however, I'm not real high on fuel additives.
I touched on this in "Does It Know Which Way the Fuel Flows" thread.

There is an inline fitting my friend swears by. It's purpose is to NOT kill the bugs, so they end up sludge. It's an inline magnet that makes the bugs sterile, where the can't multiply. Your system is a looping one where unused fuel to the injectors circulate back to the tank & then repeat the loop again & again.

There are several types on the market. Check em out.

CR

Maine Sail · Feb 5, 2014

captnron said:
It's just my opinion however, I'm not real high on fuel additives.
I touched on this in "Does It Know Which Way the Fuel Flows" thread.

There is an inline fitting my friend swears by. It's purpose is to NOT kill the bugs, so they end up sludge. It's an inline magnet that makes the bugs sterile, where the can't multiply. Your system is a looping one where unused fuel to the injectors circulate back to the tank & then repeat the loop again & again.

There are several types on the market. Check em out.

CR

I have some swamp land in Florida to sell you and a copper bracelet that will let you live to 120 years old.........

Warren Milberg · Feb 5, 2014

I've had some luck avoiding bugs -- dead or alive -- in my fuel tank by going to some lengths to avoid water getting into the fuel. I check the "O" ring on my deck fill regularly to make sure no water gets in that way. But I think what has worked best for me is always try to buy the freshest diesel I can find (from busy truck stops, not marinas that don't sell much fuel) and to triple filter the fuel with a BaHa like water separating filter before any of it goes into the tank. I also change the primary and secondary filters regularly. To me, no water means no bugs.

Maine Sail · Feb 5, 2014

Warren Milberg said:
I've had some luck avoiding bugs -- dead or alive -- in my fuel tank by going to some lengths to avoid water getting into the fuel. I check the "O" ring on my deck fill regularly to make sure no water gets in that way. But I think what has worked best for me is always try to buy the freshest diesel I can find (from busy truck stops, not marinas that don't sell much fuel) and to triple filter the fuel with a BaHa like water separating filter before any of it goes into the tank. I also change the primary and secondary filters regularly. To me, no water means no bugs.

I replace our deck fill o-ring at LEAST 4X yearly. Once you know the size you can order DOZENS of them for next to nothing... I have about 30 left and I bought 50 of them.... The cheapest insurance there is....

If I had a $1.00 for every cracked and leaking o-ring I discovered......

Another good tool is the H2Out fuel vent drier....

I buy all my fuel from marinas specifically Valvetect dealers. To carry the Valvetect line they come and physically test your tanks, fuel condition etc. multiple times per year. I have been there and seen the testing, takes the guy about an hour and the marina gets a full report after the samples are sent out for further analysis....

The idea that marinas don't move fuel is an odd one on me as the big power boats can take 1000+ gallons per fill.. One of the marinas I buy from is getting filled 1-2 times per week, in season.

TIP: Just buy where the commercial guys do, they don't tolerate down time and around here most buy from the Valvetect marinas. I don't know any of my commercial customers who don't...

Heck a boat I used to work on took its own tanker truck for fuel fills.......

Try coordinating that one when you need fuel....

Just find a marina that moves fuel and you will do fine. Even better if it is Valvetect because the fuel is physically tested to be sure it meets Valvetect standards. Here in the NE Valvetect is very strict on marina fuel quality. I can't comment on other regions....

alexco38 · Feb 5, 2014

How many people check the o-ring on the deck fill?

It's water that help breed the bugs.

I replace the o-ring every 2 years or so when I see any crack.

Warren Milberg · Feb 5, 2014

A number of marinas in my home port are mostly sail boat marinas have stopped selling fuel completely due to minimal business. The manager of one such marina told me last year that the amount of diesel they sold in a week -- during the season -- was the amount a nearby truck stop sold in a few hours. I asked him what happens to the fuel in his tanks over the winter when no one is boating or buying fuel and he said it just sits there waiting for me to fill up in the spring. No, thanks. So, wherever you decide to buy your fuel, it may be a good idea to find out just how much fuel they sell on a regular basis. Keeping your fuel fresh and clean is hard enough without starting out behind the power curve.

Maine Sail · Feb 5, 2014

Warren Milberg said:
A number of marinas in my home port are mostly sail boat marinas have stopped selling fuel completely due to minimal business. The manager of one such marina told me last year that the amount of diesel they sold in a week -- during the season -- was the amount a nearby truck stop sold in a few hours. I asked him what happens to the fuel in his tanks over the winter when on one is boating or buying fuel and he said it just sits there waiting for me to fill up in the spring. So, wherever you decide to buy your fuel, it may be a good idea to find out just how much fuel they sell on a regular basis. Keeping your fuel fresh and clean is hard enough without starting out behind the power curve.

I would not fill up there either.

If you don't have access to a marina with high turnover then I would personally Jerrycan truck stop fuel... We are lucky up here that we have enough high turnover marinas that the fuel is excellent.

Tom J · Feb 5, 2014

Maine Sail said:
Easiest and least costly no-strand solution..

Drag needle vacuum gauge

30 mic on primary

Change when drag need moves away from "normal".....

Many years ago we did a delivery on a Down East style boat that had been used in the Chess as a floating condo. The fuel was in horrible shape but this was well before commercial tank cleaners existed as a business. The new owner stocked if for the delivery with a case of 2 micron Racor 900 series filters. This guy pretty much bought everything by the case but that is another story....

Long and short is we went through all ten 2 mic filters in 1/4 of the trip. We stopped and bought ten more 30 mic filters. We made it all the way to Maine, in 4-8 foot seas, on ONE 30 micron filter and the engine ran perfectly....

I helped make a boat delivery last spring from Long Island to Cape Cod. The boat was a 28' Cape Dory trawler that had been used for the past 20 years to run to Fire Island and back to the owner's house, about 45 minutes each way in protected waters. I suggested to the new owner that he have the fuel polished and the filters changed before we took delivery of the boat. He called around, and found a guy who would come to the house and do the job there. Another marina manager told the new owner, though, that nothing grows in diesel fuel in the Northeast, because it is too cold there. The new owner chose to believe him. As you can guess, the leisurely trip with an overnight stop turned into a 3 day pain-in-the-butt delivery with multiple stops, changes of filters, and finally a tow to Westport, MA, where the old, rusty Perko filter was exchanged for a new Racor, the tank was flushed, and the fuel polished.

Solstice · Feb 5, 2014

Maine Sail said:
I replace our deck fill o-ring at LEAST 4X yearly. Once you know the size you can order DOZENS of them for next to nothing... I have about 30 left and I bought 50 of them.... The cheapest insurance there is.... If I had a $1.00 for every cracked and leaking o-ring I discovered...... Another good tool is the H2Out fuel vent drier.... I buy all my fuel from marinas specifically Valvetect dealers. To carry the Valvetect line they come and physically test your tanks, fuel condition etc. multiple times per year. I have been there and seen the testing, takes the guy about an hour and the marina gets a full report after the samples are sent out for further analysis.... The idea that marinas don't move fuel is an odd one on me as the big power boats can take 1000+ gallons per fill.. One of the marinas I buy from is getting filled 1-2 times per week, in season. TIP: Just buy where the commercial guys do, they don't tolerate down time and around here most buy from the Valvetect marinas. I don't know any of my commercial customers who don't... Heck a boat I used to work on took its own tanker truck for fuel fills....... Try coordinating that one when you need fuel.... Just find a marina that moves fuel and you will do fine. Even better if it is Valvetect because the fuel is physically tested to be sure it meets Valvetect standards. Here in the NE Valvetect is very strict on marina fuel quality. I can't comment on other regions....

+1
I stopped using Biobor a few years ago because our Marina is a Valvtect customer. However I did start using the Startron corrosion inhibiter this season (thanks to Thinwater for his testing and findings). But the real bonus came this past season when our marina decided to become the defacto fuel provider for all the commercial ferries in Boston. This includes the NE aquarium whale watch boats, Ptown fast ferries, tourist ferries, T commuter boats etc. this equates to 200,000 gallons a week. The tankers come every 4 hours around the clock. They installed high speed pumps on the outside of the breakwater and left the original fuel dock for us small guys, so we don't have to deal with waiting in line with the big guys. They also change the filters at the pumps 4 times a day. Between that and replacing the O ring at the filler regularly as MS suggests gives me a fighting chance against contamination. I do plan on installing an H2OUT vent filter as well.
Maine, where do you source your O rings from? I like the idea of buying in bulk...

Maine Sail · Feb 5, 2014

Solstice said:
Maine, where do you source your O rings from? I like the idea of buying in bulk...

Where else, McMaster-Carr....

All you need to know is the thickness, such as 1/8" and then the diameter.. The diameter of the o-ring should be slightly smaller than the OD of the ring groove on the fill cap for a snug fit and no buckling when tightened.

They sell 50 & 100 packs, depending upon the size, for about $12.00 +/-...

Solstice · Feb 5, 2014

Maine Sail said:
Where else, McMaster-Carr.... All you need to know is the thickness, such as 1/8" and then the diameter.. The diameter of the o-ring should be slightly smaller than the OD of the ring groove on the fill cap for a snug fit and no buckling when tightened. They sell 50 & 100 packs, depending upon the size, for about $12.00 +/-...

Should have known...thanks for this. I've bought them one at a time for years and obviously wa$ted a lot of money