How small is small? I'm pretty happy with my Aqua FX Barracuda. It's a 50 gallon per day unit, which was just about perfect for my 46g tank, even when I added a 30g frag tank onto the setup. Of course, that's the only one I have personal experience with.
I have a 90 gallon
I am looking to make approx 30 gallons. The problem is I live in a apartmet so i need something small touse in the kitchen or the bathtub.
The size of the RO is measured in gallon per day, which is more to do with capacity than the actual physical size.
Unfortunately, almost all RO filter are standardized so that it can have interchangeable membrane and parts. This means that there is no difference in physical size between a 24 GPD (small) unit from a 120 GPD unit. Majority of the space is taken up by the prefilters, not the RO filter. A 2 stage RO filter will take much less space than a 5 stage RO with 2 stage DI, for example.
But for apartment, you may apt for a small capacity unit that you can easily detached and attached to kitchen faucet/garden hose.
