The best solution to an algae problem is keeping your water in good condition, not giving your tank too much light and purchasing an aquarium safe sponge to scrub the algae off when you do a water change.
Even small plecos get to big for most anything under 20 gallons, otos can work in smaller tanks but require mature well cared for tanks. Algae shrimp are about the only low waste producing algae eaters, and as such are a good option for cleaning up planted tanks though they don't do much for algae on the glass.
Dojo loaches as with most other loaches love meaty foods, not algae. Dojos also get very large and practically all loaches prefer to be kept in groups. I love loaches myself, if you're going for the dojo look, a group of kuhli loaches are suitable in anything ten gallons and up. They're tropical, get on well with most community fish and are more colorful than the dojo loaches. They do need a sandy substrate and will spend most of their time hiding, though when they do come out they're very entertaining to watch.