White buildup on return tube: XD5 Res/Pump

[lukacsmw]

I have an XD5 Resevoir/Pump combo that I've been using for about a year. I've only run Distilled Water or clear EK Cryo Fuel through it. For a couple months I had it at about 50% full (I was lazy after bleeding the air) and I noticed a strange white buildup, like Calcium as well as a blue/green discoloration on the return tube in the reservoir at right about the water line. I tried to manually remove it with a wire through the inlet on top, but it's stuck hard. I took the top cover off (the leds) and submerged the tank it organic CLR for a couple hours. It did nothing. Strange thing is there is no buildup anywhere else in my loop, just on that one tube. Anyone have any other ideas how to clean it off?

[LeDoyen]

if you ran the loop with pure distilled water, then it's not necesarely organic, but more likely corrosion.

It will strip the nickel plating from waterblocks in a few weeks typically.

It's extremely bad for the waterblocks and radiators to run just on water.

[lukacsmw]

So I pulled the pump apart and discovered it’s not buildup, the tube melted!! I don’t see how since my loop runs pretty consistent around 65-67C under load. It’s melted and deformed and some buildup around the melted area. Image attached. Anyone seen something like this? I think it has to be a defective part since nothing else on the pump has melted and the motor works perfectly.

[LeDoyen]

when you say your loop runs at 65° is that the coolant temp?

if that's the water temp then you are heavily overheating.

What type of tubing are you using? soft? PETG? Acrylic?

 

I ask because PETG starts to soften above 60°C.

 

If that's indeed your coolant temp, it would help to know more about your build, maybe photos, components, to help you tame that thermal runaway