Would 3/8 ID Tubing fit on 1/2 Barbs?

Just get some primoflex black tubing. Its readily available, extremely flexible and resistant to algae as it is light proof.

Why are you trying to do this?

Most people that try to use smaller barbs use 1/2" barbs and 7/16"ID tubing, not 3/8"ID.

Again, why are you trying to do this? I see no point and you run the risk of the force needed to push this on causing permanent damage to threads or causing cracks.

Why are you doing this?

No, steel barbs do not help...you are still threading them into something else, likely delrin or plastic. The amount of force required could potentially cause you long-term problems.

Tubing is relatively cheap- $2 foot for Primochill or even less for 3/8"ID. If you really are that broke, go to the hardware store and pick up some cheap vinyl tubing at $0.80 foot.

You can possibly dip the ends of tubing in boiling water, but not sure this method would work as well as if you were using barbs/tubing closer to same ID size. Wouldn't it just be easier to wait until you had an extra $15 and get the right tubing? Half-assing it in watercooling never leads to good things.

I'm just trying to warn you- fitting 3/8"ID tubing over 1/2"ID barbs is a lot harder than you might realize. Yes, it can be done, but do yourself a favor and make sure you do it right.

If you are doing smaller tubing on 1/2"ID barbs, go with 7/16"ID tubing, it will still be a tight fit, but not nearly the wrestling match that 3/8"ID tubing would be.

3/8 barbs. If you wanted to try your stretching concept, 7/16".

I've always used matching ID tubing and barbs with clamps or good zip ties and not had issues. I know a lot of people like the 1-step smaller tubing concept and I've been thinking of trying it just to see. If you go this route, use very hot water, dip the tubing ends to heat and slide over. As they cool, they should fit very tightly.

I've also noticed that matching tubing size (say, 1/2"ID tubing and 1/2"ID barbs) nylon barbs fit much more tightly with tubing, metal barbs have a little less snug fit. It's a good idea to use clamps of some kind with barbs, especially as a beginner.

I think XSPC kits use 7/16" tubing, don't they?

Did you use distilled water and biocide or any anti-microbial? When you say murky, do you mean the tubing got cloudy like the inside was 'frosted' or was it discolored and greenish?

Would it be easier to go with 1/2 tubing with my 1/2 barbs ??

This is common with about any tubing- coolant and plasticizers cause this. Coolants stain tubing and plasticizers leech out of tubing causing cloudiness.

I'd say the largest cause of tubing cloudiness is plasticizer reaction within the loop. You can easily see the results in less than a week of loop operation- which is exactly what I saw during the testing I did.