Pseudomonas in M. Ramirezi

So I'm thinking there's a spot of pseudomonas sp. on the gold ram in the 20g. The anal fin seems to be rotted out in a very small area, there's some clamping and flashing to go with it. Not much in the white and fuzzy department. No other body marks. If it's not pseudo, it's probably some other gram-negative bacteria from the look of it.

My issue here is treatment. I'm not about to do something like throw antibiotics for gram-positive bacteria at a gram-negative bacteria. So that seems to leave me with cefalexin as the most realistic treatment I can get my hands on. The problem is it'll treat every other suspect BESIDES pseudomonas.

So I guess what I'm asking for here are scientificaly proven (journals and lab results, not hearsay and anecdote) treatments that'll do pseudomonas in, as well as other bacteria. Any ideas?

Also, water is showing 5gh, 4kh, and yet 7.8ph. The only change in variables I know of in the tank is a new source of RO. In the midst of doing a full test, but none of the fish are stressing like it's a mini cycle. What in the blue (insert expletive) is happening?

*update*
.1 iron, 0 ammonia and nitrite. Nitrates should be fine; water changes are 50% weekly and the bioload is low, with 2 min feedings. No test kit for it though. pH is equal to the tap water around here, but the KH and GH in the tank are 1/2 of tap.

*bump*
If the disease doesn't have a cure, I'd at least like to know what's up with 4kh, 5gh, 7.8pH

The infection seems to be clearing on its own. Might just do lights out feedings since the fish seem to get it all anyhow, and the ram is far less aggressive, thus less stress.

Anyhow, the strange thing with the water is that tap is 7.8 with very high hardness on both kh and gh. A water change with some questionable RO brought the hardness down, and the ph back up from 7.4 to 7.8 during a routine weekly 50% water change.

It's more the issue of understanding the mechanism because it might come up again. This tank isn't 'tope. The LFS that provides good RO water has raised prices up to $4/5 gal so we're looking some where else. I want to say ion exchange resin but usually that drops ph. The gold ram is the main reason for the params, since there might be some prospect of breeding. Some plants that like soft/low ph water are another reason. I guess my fiance and I will have to head off to the store and poke our heads in to their RO system.

I'm not sure it is ion exchange that they're using in their filters. I know it's horrid stuff, and that's why I don't use it. My issue is finding out if its what they're using, and whether its what's causing the messed up params. The problem is that there's a lot of places I have to go, and I can't imagine how many different methods these places use to filter the water. I know better than to trust a salesman, so I'm not about to trust their pitch either; I'm doing my best with what I have to find out what they're leaving in the water in each case. From there, it's a matter of finding out the best bang for the buck. I may get out hunting tommorow, but it looks like i'll be left over-paying again.

The ram doesn't seem to be flashing, and I can't see anything left in terms of infection on the little guy now. It looks like the damage is some of the fin being eaten away between the first two rays; it expanded some to include where what i'm assuming is a white eshcar or some other infected tissue/slime coat was.