I've had this tank set up for over a year now and no issues except for crazy nitrate cycle when it was first set up. I usually leave the tank light on longer than I probably should which is why I have green algae on the sides of the tank which doesn't bother me much since it's just cosmetic.
But I did about an 80% water change the day before yesterday (silly me forgot I had the tank filling back up and it started to very slowly overflow) but my fish are doing great, not flashing, gills and scales good, always excited to see me- food! But I noticed this weird purple algae or fungus mixing in with the green algae. I don't know what could even cause this. Everything I've come up with online is only for algae or bacteria that grows on all surfaces. This is only on the tank itself. And it's freshwater not a reef tank. If it can affect my fishes health I want to nip it in the bud as soon as possible.