We are starting to see 10% ethanol in
fuels here in Florida. Is there an additive
that you can use in this fuel for long term
storage?

I have used Startron's Enzyme Cleaner/preservative. It supposedly breaks down any fuel phase separation into small burnable particles.
I will warn you however, that in my big boat it helped but I still needed to install Racor fuel filters prior to the the water seps to keep from clogging the micro filter at the carbs.

Even after taking those steps, this spring I am pumping out my tanks to minimize the old fuel. This stinks because I am holding about 300 gallons right now. I am in Chicago, I would assume the fuel in Florida, would be harder to keep moisture and mold out of the tanks.

Fo my 2 cents if you are going to store for a an extended time I would empty the tanks down to 1/4 pour in a bunch of additive. At least then when you fill later the bulk of your fuel is new.
Part of the problem with ethanol is its lack of preservative. It loses 10-12% of its efficiency if it sits for more than 2 months.

Dont know if any of this helps but as a guy who lost this season due to old fuel, and after trying to burn and add, burn and add, I am still going to pay $3.00 a gallon to pump it out and then refill (575 gallons) in the spring. Best advice is to keep using the boat and keep the gas moving through the system.

Are they putting it in the fuel at Marina's also. When we we in Jax. for the Poker run, the Marina where we put the boat on the trailer, one of the guys working their saw our MD numbers and made it a point to tell us they have no ethanol in fuel at Marinas. Maybe that has changed since June.

My marina claims they are still getting pure gasoline without ethanol, but I have seen some marinas with the 10% ethanol sticker on there pumps. Some states are required to post there pumps if there gas containes ethanol

I saw an ad for Stabil Marine additive. Supposedly for fuel with Ethanol. I haven't used it yet but will probably buy some in the next couple weeks.

It really varies by state. I boat in couple of different states, and they have completely different laws regarding ethanol in gas.

One state only has ethanol in 89 octane on the road, while another state has ethanol in all their gas except that sold for marine or aviation use.

I purchased the stabil for ethanol marine use. It looks green instead of red and cost twice as much. Hope it works.

You know Marine is a nasty word. As soon as I see it on a product I translate it to mean "costs at least twice as much."

Regular red Sta-Bil works just fine. Been using it for 10 + years and with E10 gas.

remember that the ethanol is not only an oxygenate but octane as well. so you can treat fuel so it dose not turn to varnish but the ethanol still evaporates. this leaves you with a decision, treat the fuel and deal with ultra low octane fuel in the spring. or use it up or pump it out. otherwise the engine will run on the stuff but the risk of damage due to low octane is not worth it.