Mosambiques tolerate the cold for short periods. The larger the water volume, the longer it takes to change temp. The slower moving it is, the longer it stays warm.

IF you don't want tilapia...fine...but it's not an ability issue.
Snails will do it....make sure you have the right kind. Some are live bearers, some are egg layers. Some only eat other snails as is the case with the assassin snail.
There's river sucker fish, they eat algae. And I saw them in Glasgow, MT so I know they tolerate the cold just fine. They are in the Milk River there and at the damn.
Young sunfish will "graze" on it too, but they prefer meaty foods.

It's easier to advise on ways to deal with algae if you know what type of algae you have.