I currently have 7 females living in a 10 gallon tank and they get along very, very well. I have a lot of plants in the tank and some little caves for the fish to have hiding places.
The best way to have multiple females living together, is to find a tank of co-habiting females in a fish store, rather than buying the females that have been "jarred" and living separately. If they have been raised to lived communally, you have a better chance with them.
I would suggest getting at least 5. Don't get less than 4. When you only have two, one will pick on the weaker one, and with three, often two will gang up on the weakest one. When you get to numbers like 5, usually you don't get one that will be picked on. JMO.
As the previous poster mentioned, sometimes you can have a bully. You will have to keep a close eye on them for the first few days. That is when a pecking order will be established in the tank. If there is any serious aggression, then that female will have to be removed. Hopefully, though, that won't happen

Usually after a few days, the pecking order is established and the fish will settle down.
I use AquaClear mini's on my betta tanks. I cut down on the current by putting a peice of filter material hanging over the outflow of the filter. I just hook it under the lid and let it drape down into the water, then the water flow through this before it enters the tank. It cuts down on the current and I haven't had any trouble even using AC mini's in my 5 gallon betta tanks
Please feel free to ask any questions.