I myself have a seaclone 100 and I know it is not the best but if money is a prob. It works just fine. I also have a prizm on a nano and I hate that thing. It requires babysitting. I have to mess with the flow daily just to get it to work.
I'm not too sure of the price difference anymore, but the BakPak 2r is ALOT better than the Seaclone and wasn't too much more price wise back a few years ago.
IMO, it's really not worth the money that you'll spend on it even with the modifications. It may work decent on maybe a 10g nano though.
One thing I forgot to add. You may try checking out the For Sale threads here and on Reef Central for used equipment. I've found lot's of good stuff for about half price.