Hello everybody! I would like to introduce myself. Im fairly new to the aquarium world. I have a 20 gal starter tank for about a month now and i can say im hooked! I have a tetra 20 filter soon to be uupgrading to a aquaclear or fluval. I have 2 black mollies, 4 zebra danios, 3 red plateys, 5 guppies (3female 2male.) I need all the pointers i can get. Also recently my two black mollies were diagnosed with columnaris and i have been treating with maracyn oxy whats your opinion on that!?