Got this IM Fusion 20 gallon all in one setup on craigslust, then saw the inside surface to the right looks hazy. See photo attached. Previous owner said this side was away from sun light and the clear circle was where the wavemaker was located. There are a few random smaller clear circles on this side - I wonder if they tell some clues of what caused the hazy look. I have tried diluted and pure vinegar, no luck. Then Turtle Wax Heavy Duty Rubbing Compound with a sponge, and with a powered polishing tool (its surface is black foam), again no luck. I will try rubbing with baking soda, and i also have polishing compond for brass ware i will try. Is it ok to try muriatic acid at full strength on this inner surface? Anyone seen this kind of stubbon stuff? Maybe the hazy look is iched glass instead of buildup?