Melafix and other things

Question
Hi Paul,

I have a 30 gallon tank with 6 adult Mollies, 2 adult Platies, and tons of little babies everywhere.  Today I looked in and saw that one of the female Mollies had a puffy, cloudy eye.  I separated her in a hospital tank and started treatment with Melafix.  Then I was watching the fish in the big tank again and noticed one of my other female Mollies, a big pregnant one, had a split fin.  Is it ok to treat the 30 gallon tank instead of trying to put everyone in the hospital tank.  I'm worried about all the babies and the pregnant Mollie.  Also, I've heard that you have to take out the carbon filters when using Melafix.  Why is that so?

One last thing.  I have the worst luck with placos.  I do have a good amount of algae in my tank and I've had several placos, but they all die.  I also give them the algae chips, but they never touch them and the Mollies eat them.  Are those things a scam or something?  

Answer
You can just treat the whole tank.  You have to take out the carbon or the carbon will take the medicine.  I  use them for my plecos so I think they are fine.  Try to find out what the pet store feeds them so you can feed them what there used to.  

Paul