How essential is a “system prep” type of product?


Feb 20, 2008
I just finished assembling my first custom loop yesterday. Have yet to fill and leak test and was wondering where everyone falls on stuff like Primochills Sysprep and the like.

I have a bottle of Koolance that was my original plan but my tubing order got screwed and I had to order one of the PrimoFlex bundles that comes with sysprep and the biocide.

I’m already leaning towards not using the Koolance at all, and just doing distilled water and the primo utopia. I put a gallon of distilled through each of my rads (360+420) and a third gallon split between the two blocks and the pump.

This project has taken much longer than I anticipated (lol familiar story I’m sure), and I’m going to have less time to work on it in the next couple months. If I should do the sysprep first I will but if I have take it down again in 24 hours most likely it’ll turn into around a week and a half. That’s a lot of pew-pewing to miss out on.

What say you all?
Just use the Koolance? Use distilled with both Primo products? Or my flush was good enough, skip the sysprep and just fill and go.


May 20, 2011
For a new loop, system prep is unnecessary. As long as you flushed the new radiators real good you should be fine to use whatever coolant you want. I personally just use distilled & ptn nuke. I have tried utopia before, it worked fine but it did leave a slight white residue buildup in my blocks. It was very easy to clean however.