Could be diatoms, or it could be anything; really no enough to go on here. If it's not overwhelming your tank, all you need to do is scrub it off when it builds up enough to bother you.
Don't even get plecos just to remove the algae. Not all plecos eat algae and it certainly does not help. They excrete more wastes than you can cope. Sorry, this is just not a good idea.
well i don't plan on getting a pleco. i do plan on getting a synodontis eventually. with the amount of fish i currently have in my 30gal i don't think that i cud even support a baby syno until my 75 is fixed. am i right?