We have had an established 10 gallon tank for about a year. We have one balloon molly in it at the moment. The tank was going along perfectly until very recently. We now seem to have a red dust-like substance coating everything! When you wipe it with a cleaning brush it floats like a dust and does not cling to things just settles on them. The fish seems to be just fine with no signs of distress at all. We haven't made any recent changes to the tank, except our usual water changes. We do not have a substrate, just the glass bottom. We have been very careful not to overfeed and there is no food debris left in the water. There is also no salt in the water. I couldn't find anything on here about this type of dust, it is almost the colour of bricks, dark reddish orange. Any idea what's going on?