This feser one you have, UV dyed is it? Hope it isn't blue. The dye has a nasty habit of dropping out of the water and cloggin up your blocks. Whether this happens or not seems fairly random, though there have been enough instances of it to put me off any and all dyes or premixed fluids for life, *especially* blue. I still have 5 litres of feser one sitting in their original bottles next to my PC, from when I was setting up my water cooling, 3 greens and 2 blues. Make nice UV ornaments as they pick up the UV light form the case. I wouldn't let them anywhere near my loop though. Another interestung fact is that in the year they have been sizeable clumps of algae have grown in the green ones.