How many ramshorn's could I add (5.5 gallon)

[Ezzie]

Hi all!
I currently have a fully planted 5.5 gallon that's been set up for a little over a year now.
It currently houses:
1 male betta
6 nano harlequin rasboras

It also has a tiny brisslenose catfish (he's about 3cm's) but he will be rehomed soon.

I'm wanting to add some ramshorn snails to help fight the algae.
I have the green fuzzy kind that's on the glass and hair algae.
That's why I originally bought the brisslenose however I can swap him for some ramshorns at my LFS.

How many do you think I could get for the tank?

I do about 20% water change a week
Parameters for the water are all spot on:
Ammonia: 0
Nitrite: 0
Nitrate: very little, probably under 10, it's just a dash darker then yellow.

 

[Ezzie]

It's actually a little over 6 gallons, sorry.

 

[Khuligirl93]

Ramshorns will overpopulate your tank quickly just like pond snails. I have been struggling to get rid of them in my 10g for 6 months. Finally got them under control with an assassin snail.
I would suggest to get a couple nerite snails because they are great algae eaters and do not reproduce in freshwater.
It might be a good idea to figure out why you have an algae problem in the first place though. Are your lights on for too long? (Try only keeping them on 6 hours) What type of light do you have?Are you using CO2 or liquid carbon?