To answer the question, I use STA-BIL Marine Formula Ethanol Treatment (blue/green color)... Have since they started making it... I've had great luck with this that I did not have with the old STA-BIL "red" treatment. This stuff works well for me and my customers boats and other vehicles. I does have fuel system cleaners as well as non-alcohol water removers. I have recently been trying the Sea Foam in my own vehicles (thanks Mike and Jim) .... but do not have an opinion on it yet.
I've never seen algae grow in gasoline... unless there was a ton of water in the tank...Plenty with diesel though.
After fogging the motor heavily..... I've been storing my CFi sleds DRY... pulled the tank to drain every last drop, removed the injectors, blow out the fuel lines and install a new filter.
The injectors get sent out to WitchHunter performance for cleaning and flow checking $19 each for this service. (cheap peace of mind, IMO).
I install them when they are returned (they have storage chemical in them from the service) and re-assemble the entire sled...waiting to fill the tank and prime the fuel system in the fall when I'm ready to ride.
With the gas quality so poor recently and getting worse... I dont want to risk being stuck in backcountry because of fuel problems or injector issues.
I'm not saying to run the injectors "dry" either... I pull them with fuel in them and send them in for the service.
The old "fill her up to avoid condensation" doesn't work anymore as the fuel litteraly goes bad even with addatives and looses it's abilty to work.
The other alternative is to drain the tank completly and use VP fuels "SEF 94" as a storage gas.... start it up after you put in a couple of gallons and then shut it down (fog the motor heavily before storage as well). It is expensive as far as gas goes... but worth it... I may do this for some freinds that I will "summerize" for them this year. SEF-94 is about $10 gallon... but worth it, IMO, as a "tool" to protect your investment.
In the boats that I store for customers...very expensive boats... I have been using the Stabil "Marine" treatment which is the ONLY one they make that is rated for ethanol .gasoline.....I also use it religiously in any "jerry can" gas that I keep in the shop... It has fuel system cleaners as well.
After Both AK's have been talking about the SeaFoam.... I will be trying this in some other vehicles this summer and doing a test with sealed containers comparing straight gas, Stabil-marine treated and SeaFoam treated gas this summer... I think I have lined up a lab to test the fuels after sitting all summer indoors (non air conditioned).... I hope to post up the results next October.
With the sleds costing so much these days, with the crappie gas that we have available to us (even if it is non-ethanol.. the Quality is still poor comparded to years ago), with the cost of injector/fuel pump/regulator/hose issues being so high, and the PITA caused by a broken sled in the back country due to fuel issues.... I feel an afternoon of work to be worth it IMO...