Above you said you want to go "filter-less". Why you'd want to do that I'm not sure. A simple air powered sponge or box bubbler filter would be sufficient for a 10g IMO. An AC70 would be marginally insane on one. I dunno of any current loving fish that would thrive in a 10g footprint, but maybe there's some. I've personally never kept a betta, male or female that was bothered by some flow. In fact, they seemed to enjoy it.