Take 2 – The Extreme Rigs Soft Tube Test


Background Information:

As many regular readers will know, we recently concluded our 3 month tubing test which was run with Mayhems and PrimoChill Advanced LRT 1/2″ x 3/4″ tubing. It was not long after the test commenced we realized that the XT-1 glycol based coolant used was not recommended for use with the Adv. LRT tube. We decided to keep the test going anyway despite being unsanctioned and against the Adv. LRT manufacturer’s recommendations.

We strongly recommend reading the first ER Soft Tube Test before continuing further into this version of the test. The first test’s comments describe many things in more detail than I will go into detail here because this “Take 2” test is basically another version of that test with just a couple of things changed.


The Soft Tube Test Rig for Take 2:

The test rig itself remains almost exactly the same for Take 2 as it was in the original.

• Phobya Dual 240mm Radiator Stand.
• Koolance Dual D5, dual loop Pump Top & Reservoir Combo.
• 2 x D5 Vario Pumps.
• 2 x XSPC RX 120mm Radiators.
• 2 x 120mm NoiseBlocker 1500 rpm fans.
• Seasonic PSU.

Soft Tube Test Rig Front
Soft Tube Test Rig Front

Note: the following photo was at commencement of the 1st test and has the larger 1/2″ x 3/4″ fittings installed and does not yet have the fan controller attached.

Soft Tube Test Rig Business Side

The first difference with the rig from Test 1 is that Take 2 is using 3/8″ x 5/8″ tubing instead of the 1/2″ x 3/4″ used previously. The primary reason for switching sizes was availability of the PrimoChill tubing at my local retailer.

So as far as changes go to the rig, tubing and fittings are now 3/8″ x 5/8″ size.

Additionally we have decided NOT to run the UV cold cathode as this was perhaps another variable which we had no way of really knowing is there was any effect on the tubing in Test 1.

The two types of tubing being used/compared in Take 2 are;

Mayhems Ultra Clear Tubing (3/8 – 5/8) 10/16mm
PrimoChill PrimoFlex Advanced LRT Flexible Tubing – 3/8in.ID x 5/8in.OD – Retail (10ft pack) – Crystal Clear


 After plumbing up with 3/8″ x 5/8″ and new tubing the test rig almost ready.

The biggest change from Test 1 to Take 2 is the fluid being used in the loops.

Using a Glycol based coolant was a major oversight when setting up Test 1.  This was the only real reason why it was concluded.

The new fluid is not a pre-mixed or concentrated commercial coolant.
This time we are using distilled “only”. It is not actually only distilled though, because 2 other additives have been mixed with the distilled:

1: Mayhems Biocide Extreme is being used to prevent any nasties from growing in the loops.
2: Mayhems Non Stain Pink / Red Dye in see if the tubes suffer from dye absorption.  NON-stain dye was probably not my first choice, but I did have it on hand so was the main reason for using it. According to the Mayhems knowledge base the UV pink dye is top on the list of stain ability, so inadvertently the best dye candidate may have been chosen.

Next we see the mix ratios used and the left over fluid after filling both loops.

On the left you can see the actual color of the fluid as a reference. I included this because what we saw in Test 1 was that as the tubing aged and clarity became worse, the color that showed through the tubing differed from the actual coolant color.

STT-3-8-x-5-8-Start-18We always always mix more than is required for our loops and keep the remaining in a well labelled (readable at least) and sealed contained in a secure, dark location (top shelf of cupboard). You never know when disaster will strike and you need to refill or top up a system.


The final step in preparing the rig for Take 2 was to fill both loops and bleed air from the system.
STT-3-8-x-5-8-Start-12The outlet hoses are again deliberately long to enable short sections to be periodically cut out for comparison. Also on the outlets of each loop a temperature sensor has been placed for the fan controller to semi-automatically control fan speeds based on fluid temperature.  Most of the time the fans are not spinning at all.

As in Test 1, the tubing for Take 2 has been set up with the Mayhems tubing installed on the closest loop and the Adv. LRT on the rear loop.

Both loops have their D5 Varios running 24/7 at full speed (5 on the dial). As the D5’s are the only heat source for each loop, full speed and therefore maximum wattage to transfer to the coolant was the obvious choice. The radiators get each loop’s fluid temperature to near ambient, at which point the fans turn off. It takes 1 1/2 to 2 hours for the fluid temp to reach 40° C at which point the fans turn back on to start the cycle again.

With the above information, photos, and having already read our first tube test everyone should have a good understanding of the what Take 2 is all about.

Let’s get started then.

Next up: Let the test and comparisons begin….again!




  1. Cheers for the review. Did you buy it from PLE ? that’s the only store I know that has mayhem’s tubing, and for the same price you mentioned. Great work!

      • true that! Same goes for PCCG, they add shipping costs to each item on ebay, makes it look cheaper to just buy from the store website

  2. I bought the PrimoChill Advanced LRT 3/8″ x 5/8″ and the outer diameter is 1/32~2/32″ too large to use with my Monsoon fittings. I can’t get the compression ring on the thread of the barb, same thing for the tubing I received from RMA. Anyone else had this issue?

    • I can get it to fit by forcing the ring down with the free center wrench. Used the wrench to tighten it all the way. It is a tight fit.

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