Small Brown Spots On Aquarium Walls

[Smurf]

Hi All

Over the last six months or so, my aquarium has developed a growing number of small (2-3mm) brown spots on the "glass" (its acrylic really). They don't readily scrape off & my bristlenose (Dyson) is having no impact! Do I have diatoms?

If so - why now? (nothing new in tank for MONTHS and the whole set up is a few years old)

Is it something to do with lighting levels maybe?? Do I need more or less? (lights set up for ~8hrs each day and the tank receives natural light as well)

TIA!
Daisy x

 

[drobbyb]

Diatoms generally will wipe off with your finger. If you can't, then it probably isn't diatoms.

 

[Smurf]

Hmm - not diatoms then. A credit card won't remove them... anyone got any ideas what it is/how I can make it go away??

x Daisy