Algae eating fish

It might be worth trying a pleco again. They tend to kick off if the water gets below the mid-50s I believe, so you may need to capture and overwinter him indoors (or take to a pet shop). That's hard to do with a brown fish...

One option to try (no guarantees, just might be interesting) would be a few kissing gouramis. By the time you'd want to net them out to save them from a cold winter, they'd be big enough to spot. I don't know how cold they can go, but they do eat algae and can cohabitate with goldfish. They're also quite pretty.

I'm thinking of trying rosie barbs next in my pond to help with algae. Heard they were great algae eaters! My pleco got to approx 1 1/2 ft long in my pond before it finally died. It was too big to overwinter inside.

I have heard great things about the Chinese Hi Fin Shark, you may want to do a little research into it before you buy though. They are really cute as Juveniles, but as adults they are not very attractive, and can get BIG.

http://www.petsolutions.com/Hi+Fin+Banded+Shark-I-63215-I-C-40001598-C-.aspx

glamp, algae eaters may not eat old established algae, they mostly keep fresh algae from reasserting itself. you may have to prune and/or bleach dip a lot of plants, adjust lighting, feeding, and water chemistry, and maybe then a nice compliment of algae eaters will help keep things tidy even when you slip up.

Plecos are most useful at keeping wood, plastic, rocks and glass clean. they will do little for your plants. to keep plants clean you need a smaller mouth rasper like Ottos, Farlowellas, and algae nippers like SAE's and Flag fish.

Florida Flag fish Jordanella floridae would probably be the best idea for a pond since they are the most resilient besides Plecos.

keep in mind that many algae eaters can get lazy, and simply eat left over fish food instead of algae, so it's important to starve your tank to not only reduce water pollutants that feed the algae, but to condition your algae eaters to do their job.