Originally Posted by Narco944
i think i get it too...or a kind of red algae. about once a week it starts to spread and cover the walls. water change or no water change it always happens. i just wipe it down with a magic eraser.
The red is likely cyanobacteria which tends to be fueld by nitrates and phosphates. Their fertilizer comes from food and fish waste, but can also come from your source water. Diatoms are generally brown and fueled by silicates. The reason they tend to clear up on their own is that you introduce very little silicate over time. It tends to orginate in the rock and sand.