I have a 100G tank with red spots on the glass only?

Question

I have a 100G fish tank with African Sicklets it has been healthy for around 2years now. the fish are breeding and all my tests are normal ranges. In the last 2-3 weeks I have noticed redish-brown spots that have appeared only on the glass. I can scrub these off with the brush but it requires alot of force. what can cause these and how do I prevent it from happening again?

Answer 1

Sounds like your brown stuff are diatomes (sometimes refered to as brown algae). These usually apear in new tanks. However, they can apear in established tanks and it usually means a fluctuation in nitrate or phosphate levels.
Do more frequent, smaller water changes, be sure not to over feed, and keep scraping it off the glass if it apears.

Also, it's Cichlid, not Sicklet :)

Answer 2

your red spots are caused by either too much light or too many nutrients in the water, or both. Does the tank get direct sunlight- this will cause this. Also you said the Chiclids are breeding- they may not be eating as much as they used to and they are probably creating large amounts of waste as they mate -increasing the nutrient levels. Do 25% water changes about every 2 weeks and clean the algae off the glass, invest in an algae eating fish like a chinese algae eater and start feeding a little less for now.

Answer 3

You have red algae, it sounds like. It is almost impossible to get off. Try using a sharp utensil such as a pencil, or look in an aquarium store for a solution that could prevent it from forming.

Answer 4

Alga, harmless, but ugly. Just clean off the glass regularly and it will be fine. Sounds as if your pH has shifted one way or another. Bring back to slightly acidic for the chiclids. The easiest way to do this is to add peat moss to your outside filter...softens the water and adds acidity to it.

Answer 5

Its algae, you can get a proprietary anti algae treatment in most pet stores...;