Hi there, I was cleaning one of my old systems and realise that the tubing is all white cannot see the water any more. Also the reservoir has some sort of stain on it that looks like sugar dried up and stuck on it and I cant get anything small enough to fit into the hole to clean it. What is this and how can I stop this on my new loop? I have purchased new tubing and cleaned the radiators (hopefully its good enough). I previously used distill water and liquid utopia.