Algae Eaters For A 20 Gal?

[KrystaK]

I have a 20 gal female betta tank. It is near a window and as such has algae problems. I dose with liquid CO2 and leave the light on for about 6 hours a day. (But as I said it's buy a window so it gets natural light too.) 
 
My stock is:
6 female bettas
2 Juli corrys (I know two isn't enough but the bettas are pigs and usually eat any sinking food before the corys get to it)
a myriad of assassin snails. 
 
So I'm having trouble keeping the algae at bay. I want to add a fish that can control algae, as I cant use an algae eating snail with the assassin snails in the tank.
I don't really want any ottos as they need to be in larger groups and I don't think there is room for a group of fish.
With that being said, I wanted to get a BNP, but I dont know if there is enough room for one with the bettas and the corys (Especially if I up the number of corys to 5 or 6 to make them happier.) 
I just wanted someone else's opinion on how many fish I can fit in my tank, 

 

[TallTree01]

Tbh, I don't think that a BN would be happy in a 20 gallon permanently ( im going somehwere with this ) . I see from your sig that you have a BN in your 30. If it were me, I would switch the BN from the 30 to the 20 for a couple of weeks or until teh algae is controlled. The shrimp may also help but I think the bettas may snack on them . As for Plecoes that I'd put in a 20 permanently, I'd say either ottos or ..... Nothing.

 

[Zante]

How about a few amano shrimps? They should be aggressive and large enough to keep the bettas from snacking on them.
 
Also the assassins shouldn't be much of a problem with larger snails, like apple snails.
You could also try and remove as many assassins as possible, you won't find any trouble in finding people who'd buy them.

 

[bigcheed]

i keep apple snails in my tank with assasins. there far too large for them and dont even try. i also have 5 ammano shrimp. these guys are the buisness at cleaning up. anything.

 

[betta fish]

Nerite snails are an excellent choice for algae infested tanks, much better than apple snails for this purpose in my opinion but I would be worried about the assasins as they don't get as big as apples but having no experience with assasins as I like snails in my tank lol I don't know how big a snail needs to be to not be predated, switching the bristlenose if you have one from the bigger tank for a bit may work but they tend to get lazy with age, juveniles are far more efficient algae eaters

 

[SamB]

What about ottos?
EDIT Muppet points for me. I didn't read very well there.

 

[wrightt3]

Zebra plecos, clown plecos and goby plecos could all work in that tank. Many people say 20 gallons is too small for bristlenoses but I have successfully kept and bred them in 15 and 20 gallons for a number of years. However if you decide to up the size of your cory shoal (which you should) then there would be too much competition for food to have them so I would stick to  one of the others I mentioned if you want a Pleco.

 

[KrystaK]

Upon some research into the pleco's you mention I wouldn't mind having a Clown Pleco (As apparently the Zebra's are quite expensive and require more room) But that being said, as I'm planning to up my number of corys I feel it would be more wise to clean out as many Assassins I could and get some other snails and/or shrimp to help with algae control. 
And find someplace away from the window to move the tank to.
 
Thanks for the help