Filtering a large volume of coolant


Limp Gawd
Oct 5, 2009
My system uses a mesh filter installed in the case to clean the Feser One coolant as it enters my internal loop and I suspect there is sediment/particles in the fluid that are getting through and causing fouling inside my CPU block. I've already had to remove the block twice to clean it, so I want to do a thorough straining of the coolant before powering everything up again.

What's a good way to filter 4L+ of coolant? I have coffee filters, but I'd like to have something inline that works with the pump. I saw a few inline water filters at Home Depot, would those do a good job? I wouldn't be using the filter while the system is running as I'm sure the flow rate would be far too low. - Home Depot filter link
I'd imagine that you just want any 5-micron or so sediment filter. I think that HD filter would work (I'd check the specs), but if you have VISIBLE particles, then try the coffee filters first.

Edit: That filter is sediment + chlorine + scale... I think I'd rather use JUST sediment for an Aftermarket Coolant. I'm not sure what Feser has put in their coolant. [5-micron sediment = no particles larger than 5-micron will pass through]

Ebay has inline sediment filters for less ($11-$15 shipped), but you'd have to wait on it..

Search terms would be: "5 micron sediment" or "5 micron inline sediment" ... or variations of that... - There are several brands

5-micron is already quite small, but if you wanted, you could go for 1-micron (This will be harder to find in a ready-made inline filter. You'll likely find the DIY filters (which are larger and require a filter housing with inlet/outlet at the top, commonly seen in the better home Reverse-Osmosis systems)).

We DO start with DISTILLED water, so realistically, even 1-micron should be fine. But you're using an aftermarket coolant, so I'm unsure what the protocol should be.
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I installed a filter - essentially the same on in the link - upstream of my pump and my machine is running again. Flow has dropped, but still consistent, so I think i'll just use the filter temporarily for a few weeks while the stuff gets lifted out.
I have a question.

Are you looking to filter it in your loop or are you looking to filter it before it gets to your loop during filling. Because if there are low micron (2 or smaller) from the bottle the most likely cause of the buildup is something is corroding in your loop.

It’s that or you might wish to consider using a different coolant or even distilled water with an algaecide in it.

I've played with some in line filters and found it to be more of a pain then it was worth. I do how ever filter my coolant before it enters my system with a coffee filter. Just to make sure any thing that settled in the bottle or small bits of plastic from the bottle don't get in.

I was having problems with stuff getting into the stream till I realized I was having a reaction to using an older and newer bottle of coolant that apparently the make of up the formula changed. I didn’t see the warning not to use with older bottles. Do’h!

If you are also using a dyed coolant that can cause issues with most low micron filters as the dye is often very large (relatively speaking) around 5-25 microns. Some use smaller but I would not count on it. Easy way to tell is if the color looks like it fades a little over time. The smaller dyes cost more money.

I would run with JUST Distilled water for a few days to clean things up and dislodge anything that might be in your radiator(s). And use a dye free coolant. I don’t know the coolant you are using so I can’t comment on its properties.

Good luck!
I was worried about the dye...

Do those Reserators have aluminum in contact with the water? Is that causing any problems?

Also: I'm surprised that you have a usable flow-rate with the filter installed...impressive.
I was worried about the dye...

Do those Reserators have aluminum in contact with the water? Is that causing any problems?

Also: I'm surprised that you have a usable flow-rate with the filter installed...impressive.

I think the dye is actually coming out slowly, so I likely won't leave the filter for more than a few weeks. I'm considering replacing the block with the EK Supreme HF shortly, so once that happens I'll remove the filter, and hopefully most of the junk will be out. There actually seems to be a lot of material inside the larger mesh filter I've been using for a few months, so I'll clean that while I'm at it.

As far as I can tell, the Reserators are extruded aluminum. Since both were purchased "preowned", I figured the stuff stuck in the filter was leftover from whatever coolant they used.