Red Algae in Fishtank

[Izzie]

I have a 3gal freshwater Eclipse Aquarium that I keep my halfmoon betta in.
When I brought everything home from college in SD this christmas, the tank froze overnight during a stopover (betta safe in a travel container inside).
Was pretty unavoidable, didn't think it would be a problem.

Got home, of course the few cheap plants I had were dead, as was my HUGE snail population- kind of happy about that originally. They were the smaller long skinny ones- I probably had <50 of varying ages.

However, after a couple weeks, I encounter a problem. I sterilized the entire tank when I got home since it sat for a while (couple weeks) before I set it up again, however:

Within a week of cleaning the tank, I get a large red algae growth on the decorations I have in there. Betta just not impressed with the situation. The algae is red-brown, I can take pictures if requested.

I have a biowheel with my filter, so there is some healthy bacteria in there, apparently no more in the tank. I've been doing water changes/scrubbing every two weeks to keep up with the growth. pH has been okay, I do have a way to adjust/measure it, haven't checked recently.

Should I break down and get snails again? I got the little ones because they didn't creep me out like the huge 'mystery snails' you can get at Petco/Petsmart.
Being only a 3 gal, I don't know if can support an algae eater like an oticynclus.

ETA pictures of the obviously tortured betta. (his name is horus)