Eyeless: If you have slime, foam and an odor of stagnant water you probably have algae. If you have light and water you'll get algae. Take a glass of water, put it in a sunny window and see what happens, eventually it turns green, that's algae. Your reservoir temperature seems fine. I'd leave that alone. Algae like a warm environment not a cold one and cool is cool/good. But now you have nutes and algae are plants and they eat nutes.
Here's what i suggest: if you have a shower head on your bath tub, even better if it's on the end of a hose, give yur roots a good power wash with what ever water pressure you have. Next, rub a dub dub and scrub your reservoir until it's spotless. Refill with fresh nutes and add some Hygrozyme plus a cap full of hydrogen peroxide per gallon. Not the commercial stuff that will burn a whole in your floor; the 3% stuff you can buy over the counter at the pharmacy at Walmart.
You're not done yet. make sure that there's no light getting into your reservoir or before long you'll be back to square one. I feel your pain because I had the same problem a few years ago in an Aerogarden and now i'm a lot more careful about sealing off my reservoir. I hope this helps. Please keep us posted on your progress. Good luck. HSA