There are many posts that recommend running the powerheads in either white vinegar or some diluted muriatic acid ... That does remove hard build-ups but, how do you remove the thick algae build-up. Feels almost like moss, and despite prolonged stay in vinegar, it does not come off. I've used an old toothbrush in the past, but that's good for simple shares/. Good luck cleaning a koralia PH with a toothbrush.
Any clue?
Any clue?