Threaded Plumbing

[d2mini]

Hi all, just curious what you think is the best way to make threaded plumbing watertight, rather than slip plumbing with glue? Plumbers tape? Something else? And who likes to use threaded vs slip?

When i put together my current plumbing setup with expensive sch 80 pipe and valves, i used slip fittings and now those expensive valves would be trash if I ever need to change things up.
I need to add one or two to my system and plan on going with threaded this time.

[hllywd]

Your existing plumbing isn't necessarily "trash" when you need to change it... If you ever did need to take it apart, assuming you have the space, you can cut it and add unions that would allow reassembly. I would recommend the same with your new additions.

[ryanerickson]

I'm a plumber and I would suggest staying with the slip fitting threaded seems to always find a waY to leak on my reflow pump I had to connect a 1.5 threaded fitting I used Teflon and then reef safe silicon year and a bit later it found a way to slowly leek. As hllywd said use unions if wanna cut and put back together. And by the way sch 80 is crazy over kill on a reef tank sch40 is just fine. In canada we use sch80 for higher pressure lines in the dirt. Example water distribution under a large warehouse.

[d2mini]

Your existing plumbing isn't necessarily "trash" when you need to change it... If you ever did need to take it apart, assuming you have the space, you can cut it and add unions that would allow reassembly. I would recommend the same with your new additions.

Yes, I plan on that if I have a problem and have the room.

[d2mini]

And by the way sch 80 is crazy over kill on a reef tank sch40 is just fine. In canada we use sch80 for higher pressure lines in the dirt. Example water distribution under a large warehouse.

haha, yeah i know. But it really looks nice with my gray walls. :D

[Texas Paul]

I use both, but try to stay away from threaded fittings on the pressure side of any pump. I also use large ID vinyl tubing and barbs to make any drastic turns and keep friction low. It seems to really help my DC pumps run high volumes at lower speeds -keeps them dead silent.

[Da Maui life]

I'm a plumber and I would suggest staying with the slip fitting threaded seems to always find a waY to leak on my reflow pump I had to connect a 1.5 threaded fitting I used Teflon and then reef safe silicon year and a bit later it found a way to slowly leek. As hllywd said use unions if wanna cut and put back together. And by the way sch 80 is crazy over kill on a reef tank sch40 is just fine. In canada we use sch80 for higher pressure lines in the dirt. Example water distribution under a large warehouse.

That’s why it leaked look into what lasco and others recommend, and you’ll find it’s not Teflon and certainly not silicon. Use a paste designed for PVC fittings such as Rectorseal #5
Teflon can distort threads, and cause one to over tighten damaging fittings.

[Da Maui life]

haha, yeah i know. But it really looks nice with my gray walls. :D

You have options other then SCH80 if gray is what you want. One can find SCH 40 pipe and fittings in many colors including gray, check out BRS, Amazon.

[uncleof6]

I'm a plumber and I would suggest staying with the slip fitting threaded seems to always find a waY to leak on my reflow pump I had to connect a 1.5 threaded fitting I used Teflon and then reef safe silicon year and a bit later it found a way to slowly leek. As hllywd said use unions if wanna cut and put back together. And by the way sch 80 is crazy over kill on a reef tank sch40 is just fine. In canada we use sch80 for higher pressure lines in the dirt. Example water distribution under a large warehouse.

Well, it is not surprising that you are having/have had problems with keeping the joins with your reeflo pump from leaking. The instructions, supplied with every pump Reeflo sells, clearly state to use a non-hardening thread sealant NOT teflon tape. Using silicone obviously does not help one bit, and silicone + pvc is a really bad combination.

The PVC fitting manufacturers (Lasco and Spears in particular) say that tape is the wrong way to seal PVC threaded joins, and that a non-hardening thread sealant should be used, as even a single wrap of tape, starts to deform the threads/fitting becasue the threads are tapered; tape lubricates the threads encouraging overtightening which further distorts the threads/fitting. They also say that a thread sealant, that does not contain teflon, should be used, as with plastic fittings a lubricant is not needed nor desirable.

Tape is for metal threaded fittings to prevent galling. Plumbers that actually get this right are the exception, not the rule. ;)

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As to the general discussion in this thread, in just about every case, only two threaded joins are required in an aquarium system and those are both at the pump: the inlet and the outlet. (just the outlet for submersible.)

Although threaded fittings are way overused in the aquarium hobby, sometimes you have to use them (case by case basis, at the pump for instance.) Use a non-hardening thread sealant, and follow the directions (e.g. read them) By applying the sealant per directions, the odds of a leak developing are very slim.

Union use in aqaurium systems is also abused. Again, there are only two unions required: both at the pump. Much of the time, unions are not installed properly and are overtightened, which causes leaks. Overtightening damages the o-rings. Union o-rings should be lubricated to prevent damage using a silicone lubricant. Hobby wise, the only supplier that markets this product is Lifegard Aquatics, part number: R172036X. Nothing should be applied to the union body threads, the o-ring seals the union, not the body threads. Hand tight is enough, tools should not be used.

That leaves solvent weld joins. Folks are lulled into something of a false sense of security, that being solvent welds won't leak. That just isn't true, and the "leaks" can be more insidious and difficult to find. Often a leak in a solvent weld will not show water, but will suck air in creating micro bubbles in the return plumbing, and preventing siphon drains from working properly.

The directons on the cans of glue are pretty clear, but many do not read them. (Incidentally, the directions state: use primer IF required. This is alluding to building codes. It is also makes it pretty clear that primer is NOT required for good solid solvent weld joins, unless the pipe is "dirty", i.e. been buried in the ground.) Poor gluing technique is responsible for leaks in solvent weld joins, (folks seem to think primer will take care of this, it won't.)

I don't think it matters what type of joins you have in your system, because leaks are caused by not following the directions, not an inherent flaw in a particular joint type.

Sch 80 is a real waste in this hobby. However, Sch 80 unions and valves (with viton seals) hold up better, than sch 40 valves and unions. (I use sch 40 spa fittings for connecting pumps, but just the same.) But with sch 80 valves and unions, there should not be a threaded connection to the rest as both Lasco, and Spears recommend agains mixing sch 40 and sch 80 theaded fittings.

[shifty51008]

I use threaded fittings whenever I connect a ballvalve or union cause I use the cpex and spears stuff and would like to reuse them if I ever change things up. has worked for me for 6 years and no issues.