I have a Fluval Chi tank, and on the top there's a tray where you can put stones in for decoration. This tray sits on top of the filter. The filter draws water from the tank, shoots it up through this tray (an opening can be found under this tray) and through the stones and flows back down from the sides into the tank.
So I have been running this tank for about a month and a half now with a few guppies in it. Yesterday, I just noticed that the stones in the tray have white gooey stuff attached to it. If you look at the picture, the dark rock in the center of the picture has white spots. Those are the gooey stuff that were not there orginally when I first put the stones in the tray.
is that the good bacteria found in a healthy tank or is it something that I should take care of? Also, sometimes I find that the water surface seems a little oily. Could that be a side-effect? thanks.