So I've just restarted work on my WCing after a 5~ months due to getting put off that I had killed my MB/GPU/RAM (turns out I may have bent a few CPU pins) and have opened up the system to clear out water I may have left in there (only rads, res and one pump, no blocks and not connected in a loop). Got some out of the front rad (was water I had been using, deionised from supermarket + biocide) but noticed that the inside of my tubing was white.
Can't see anything like this on my UV green tubing that's been sitting on a bench since I disassembled the loop several months ago but I noticed a buildup of black stuff on the CPU block when I went to lap it to clear off the liquid metal (at least I remember seeing a darker area, didn't have much luck cleaning it with a toothbrush when I tried iirc)
Would this be just plasticising or could there be algae because I left the loop a lone for so long? Recommendation for replacing tubing or cleaning? I was going to run pure deionised water through rad/tubing for a bit then some more with biocide in it before I connect up the blocks but should I do more?