Algae problem...

So my twenty gallon tank has started to get some algae issues since we had to get rid of our pleco that was outgrowing the tank... I really dont want to have to get another one that I will have to just get rid of in a bit. I also have never ever had luck keeping ottos alive for more than a month. Whats the best option for something that will quickly deal with the issue and not die or outgrow my tank?

bristle nose pleco.

they only get about 5-6" long

See I think that even they are a little too big.. They produce so much waste! That is why we got rid of the first one... We leave for a week and come back and there was so much poo everywhere lol. He was probably only 5 inches when we sold him. But if it really is the best option I will try and track one down. The old guy did keep the tank spotless.

Siamese algae eaters

snails

both are really good at eating algae, careful with the snails though!

Nerite snails are great at algae munching and they don't reproduce in freshwater.

Floating plants (like frogbit or duckweed) help suck up nutrients that would otherwise feed algae. Or you could plant a larger plant outside the tank with roots that trail down into it. Depending on the tank size and the amount of light the plant has outside of the tank, this can work really well - mangroves are fantastic at nutrient uptake directly from water.

I hate nerites, them laying little white eggs all over the aquarium glass would have been fine if it were actually possible to get them off. I tried absolutely everything to get those eggs off, just had to wait for them to decompose. And then you have to make sure any tiny opening in the tank is sealed because they will climb out. All of mine ended up on the living room floor shriveled up so... Some people really enjoy them so more power to ya if you do.

Whatever animal you choose is going to produce waste so if too much waste is your main issue aside from algae then you'd be better off not getting an algae eater and doing more water changes or as pbmax suggested adding more plants.

Otto's dont get any larger than 1.5"