I've been running this custom loop for a little over a year now and it's been working great. No leaks, low temps, nearly silent. I noticed the coolant in the res looked like it lowered, not uncommon as air bubbles work their way out of the nooks and crannies. I went to add a little but when I unscrewed the fill port, the coolant was backed up all the way to the top. Has my loop built up pressure due to the heat cycling? Would my loop benefit from a pressure relief valve on the res? I don't want it to start bursting at the seams.