I've been going back and forth on doing a water loop for my last several builds but have never pulled the trigger because I wasn't sure it was worth the time and hassle. Now that I'm getting ready to do another build I'm having the same debate (again) and I think the look/durability of hard line may have tipped the scale. I came upon this thread because I was looking for some info on the differences between acrylic and PETG and I have to say: some of the nonsense in this thread (and elsewhere) is pretty appalling. I don't have a horse in the race (so to speak) so I thought I'd post some of my thoughts on the subject:
1) People need to understand that there is a LOT of bad information floating around the internet and you need to fact check before you post. I've seen a number of "tutorials" on how to bend acrylic that are flat out telling people to do things that will compromise the strength/integrity of the material. For example, I've seen a bunch of people saying to "quench" the tube after bending it... which is a TERRIBLE idea. Bending acrylic isn't like forging a sword, and most materials when taken from hot to cold to rapidly will be weakened tremendously if they don't flat out break. In other words: there are a lot of people out there who don't know what they are doing, and the fact is that acrylic is only prone to cracking or shattering if you've done a poor job of heating/bending it. It isn't brittle or weak at all, so it's pretty safe to assume that people who have had problems like that are almost entirely from user error and not some characteristic of the material.
2) If you're going to claim a position of "expertise" as a way to validate your argument (such as being an Engineer) then not only does your information have to be correct, but also relevant. I saw someone post a few pages back about how PETG actually has the higher melting point and they went on and on... but the entire argument is baseless. Why? Because it doesn't matter at what temperature the materials melt, it only matters at what temperature they deform. It is a fact that PETG deforms (and thus bends) at significantly lower temperatures, which means that in the event of a major failure where the system continues running (and heating up) the PETG tubing will deform in situations where acrylic won't. Even if PETG does have a higher melting point it's meaningless because at those temperatures the machine is toast regardless of which material you've chosen. Context is a thing, even if he/she was technically correct it wasn't relevant and only serves to confuse people by muddying the discussion.
3) People need to stop bringing up the "hammer" test and tensile strength and all the other things that either: a) don't apply or b) they don't understand. I'm not sure if the video I saw was the same video people were referring to, but the one I came across was so flawed (and biased) that I was literally laughing at how absurd it was. First of all, the method of heating was inconsistent. He had no way of controlling the rotation or distance the materials were heated at and didn't have any clear indicator of when the tubes were properly heated. Second, he waited pretty varied amounts of time between when he bent the tubes and when he "quenched" them. Third, he quenched them. Which aside from having a negative effect in general, has a differing impact on either material (IE: it doesn't affect each equally) and regardless of any other factors invalidates any "conclusions". Fourth, in the other tests (snapping/hammering) the force being applied was neither measured or consistent. It was pretty obvious even to a casual observer that he was skewing his tests in order to achieve his desired conclusion. Finally... none of it matters, because no one hammers their system and most people don't even touch, let alone move their towers, and if you do then perhaps you should take measures to make sure you protect the system and NOT DROP IT.
4) Everything has pros/cons, and neither material is the IDEAL solution for everyone. It depends on what YOU value most. For someone who doesn't mind the time/cost of learning to bend acrylic properly then I'd say it's clearly the better material, but that isn't saying it's better for everyone, just in that situation. For someone who doesn't want to spend a lot of time/money learning (and re-doing) bends to get them perfect, then PETG is going to be much simpler/easier and is clearly going to be the better material. It all comes down to each individual making their own choice.
5) You need to understand the motivation behind how/why companies would choose to release a "new" product that competes with their OWN products in the same category. It would need to either a) be a vastly superior and thus more expensive product, or b) be a cheaper/easier to manufacture product that will cost less or provide some other benefit to the company. If PETG was the superior material (in general) then I can assure you it wouldn't be less expensive. Period. Not even if it was vastly cheaper to manufacture, if it was better it would cost more than acrylic unless the market was dying and lowering costs was the only way to continue making money. Typically innovation that ALSO lowers prices happens when the lower price point is going to "unlock" significantly larger consumer bases (and there are plenty of examples of it), but water cooling is a TINY niche market even among enthusiasts that are themselves a tiny niche market. So innovation (superior product for less) doesn't apply, because there would be no pressure or motivation for the companies to lower prices.
Well this got longer than I intended so I guess I'll stop there, but hopefully you get the idea...