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What's the best way to clean out your watercooling system?

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Senior Member
Feb 15, 2001
Harford, WI.
Do you use a chemical of some kind?

Reason I'm asking is when I installed my new block last week sometime I didn't have any distilled water on hand. Well I used some tap water and didnt add any Antifreeze along with it. Now around a week later my temps have went up a few degrees and the water is not really clear anymore!

I want to clean the system out and start fresh with some distilled water but I want to be certaing I get all the crud out.
get some muriatic acid and dilute it down some and use that. its 6M so don't use it pure. You should dilute it to about 1 molar. the formula is M1*V1=M2*V2. M is the molarity and V is the volume. Don't worry about units, as long as you are the same on both side. Don't leave it going through too long, especially if you have aluminum stuff in there. Would be nice to flush it with dilute strong base too if you get some. If you have an all copper setup you are good with Muriatic acid. That should do it.
Bleach water should work fine, run it through the system to kill any algae/bacteria that has formed. You could also go to the auto parts store and get a radiator flush, they are designed to get rid of all kinds of crude that builds up in aluminum radiators, you need to get one that doesn't require the heat from the engine though, most want you to start the car just to pump the chemicals, but some actually need the heat (I guess you could put the water block on the stove in that case... :) )