Mixing bolivian rams and blue rams would not be a good idea, your tank is too small.
A few years ago I tried both in the ame tank and the bolivians managed to beat the blue rams into submission so much so I had to rehome them
I have tried using them, but after a while I wasnt sure they were worth it? you only have to have your hand in over the top and they fill with water, Ive never found a long pair that were good for use in an aquarium in my experience
Flubenol 15 has a half life of 7 days, so use it weekly when needed.
You dont need to do a water change after using it - makes do difference, when you do, just mix it with a little tank water and add it to the tank.
It will go cloudy, but that will clear up and the water will look very clear. :)