Better pic of the flat spot...
You can see that the rocks should not be causing an issue since they are all smooth and large. I do not think the Tetra caused the damage. The Tetra has become the most calm fish in the tank and almost never goes into the bottom half of the tank where the Pleco spends its time.
My QT tank would be a totally uncycled 2.5g Mini Bow. I think the Pleco would produce enough waste in one day to cause water issues even if I changed the water all the time. If the Pleco gets worse, he will end up in the QT tank, but I am trying to avoid it if possible since I think he would be doomed and stressed in a tank that small. I need a cycled 10g tank with some snails or something in the future...
In other news... There are baby Cherry Barbs in my tank
I do not suspect they will last long, but I am thinking they are a good sign that the water is OK.
2x Sunburst Platys (2M, 2F) // 3x Neon Tetras (?) // 2x Cherry Barbs (1M, 1F) // 2x YoYo Loaches (?) // 1x Bushy Nose Pleco (M) // 1x Clown Pleco (?) //
-30# Live Rock
-Mixed Snails (Nassarius // Cerith // Astrea // Black Turbo // Mexican Turbo)
-8x Blue Leg Hermit Crabs // 1x Banded Serpent Star // 1x Cleaner Shrimp
-1x Royal Gramma // 1x Percula Clownfish
-2x Mushroom Leather // Metallic Green Star Polyps // Pulsing Xenia // Striped Xenia // Blue Mushroom
-Remora + Maxi-Jet 1200 // 2x Maxi-Jet 600 // Maxi-Jet 400 // Visi-Therm Deluxe 50 // Current USA Orbit 2x 40w PC