I don't think you can prevent algae from growing if you leave the pool closed THAT long. But here's how I close:
1) get the water PERFECT and clear and raise FC to shock level. If it's going to be warm for a while, I'd consider raising CYA levels to 60 or 70 ppm and using 20ppm as my FC shock level.
2) add an entire quart of Polyquat 60% algaecide (that's a type, not a brand. If it has "Poly....<something>...60%" and nothing else as the ingredients, that's the stuff, no matter what they call it.)
3) wait 48 hours. FC will drop precipitously from the Polyquat--that's OK and normal.
4) run the FC back up to the shock level for your CYA.
5) Close.
The only thing I see you can do is add more polyquat--two to 3 quarts total, but no more. It should get you through the winter with clear water.
But I think it's a crap shoot either way, since it sounds like you will have NO maintenance on your pool for a year.
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