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These are each half of a slip/socket type (glued) Union fitting!These are labeled as “union connector kit” but doesn’t show where they’d go.
Assuming the 1 inch plumbing from waterbox you’re referring to is rigid, it’s actually capable of flowing right around the same as 1.25 inch hose/tubing!The Sicce SDC 6.0 outputs a 1.25inch soft hose connector and the Waterbox uses a 1inch.
I just looked up the SDC 6.0, the hose barb is tiered. From what i can see the top half of the barb fits 1in tubing and the bottom fits 1 1/4.Nah. Apparently it’s common that the pumps don’t line up with the tank plumbing? I had to order an adapter that hopefully works. The Sicce SDC 6.0 outputs a 1.25inch soft hose connector and the Waterbox uses a 1inch. Frustrating as hell that there’s his last mile that apparently nobody in the industry has resolved as I know at least 2 others that ran into the same plumbing challenges. And it’s not a random part readily available at Lowe’s or Home Depot without several adapters.
You’re correct. The Waterbox take a 3/4. I might have misspoke earlier.I just looked up the SDC 6.0, the hose barb is tiered. From what i can see the top half of the barb fits 1in tubing and the bottom fits 1 1/4.Nah. Apparently it’s common that the pumps don’t line up with the tank plumbing? I had to order an adapter that hopefully works. The Sicce SDC 6.0 outputs a 1.25inch soft hose connector and the Waterbox uses a 1inch. Frustrating as hell that there’s his last mile that apparently nobody in the industry has resolved as I know at least 2 others that ran into the same plumbing challenges. And it’s not a random part readily available at Lowe’s or Home Depot without several adapters.
Thank you for grabbing parts and looking that up! I agree parts would be for a UV Sterilizer.These are each half of a slip/socket type (glued) Union fitting!These are labeled as “union connector kit” but doesn’t show where they’d go.
Google didn’t yield any good exploded diagrams of a union fitting, so forgive my crude attempt with one I have laying around:
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As you can see, there is a side with a sealing O-ring, and external threads… then, an internally threaded locking collar, and another side with a flange/shoulder for the locking collar to clamp against…
Note that this particular union is National Pipe Thread (NPT), vs. yours which is slip/glued!
— my best guess is that these are for a UV sterilizer, given that you have two single halves of two unions… the other half of each union, and the locking collars would be integrated into the UV sterilizer’s body!
Sorry I misspoke. The Waterbox comes down to a 3/4.Assuming the 1 inch plumbing from waterbox you’re referring to is rigid, it’s actually capable of flowing right around the same as 1.25 inch hose/tubing!The Sicce SDC 6.0 outputs a 1.25inch soft hose connector and the Waterbox uses a 1inch.
— to explain, rigid PVC pipe (schedule 40,etc…) is typically measured by Inside Diameter (ID)… tubing, even when measured by ID, doesn’t account for the associated barbed fittings which seats inside it, not outside it…
This said, the 1.25 inch barbed hose fitting coming off the pump probably has a ID closer to 1-1.1 inch; nearly identical to 1 inch rigid PVC pipe!
3/4 barbed.Sorry I misspoke. The Waterbox comes down to a 3/4.Assuming the 1 inch plumbing from waterbox you’re referring to is rigid, it’s actually capable of flowing right around the same as 1.25 inch hose/tubing!The Sicce SDC 6.0 outputs a 1.25inch soft hose connector and the Waterbox uses a 1inch.
— to explain, rigid PVC pipe (schedule 40,etc…) is typically measured by Inside Diameter (ID)… tubing, even when measured by ID, doesn’t account for the associated barbed fittings which seats inside it, not outside it…
This said, the 1.25 inch barbed hose fitting coming off the pump probably has a ID closer to 1-1.1 inch; nearly identical to 1 inch rigid PVC pipe!
No worries, so the waterbox soft line is 3/4 ID? it does not fit on the barb at all correct?Sorry I misspoke. The Waterbox comes down to a 3/4.
Ah, okay! So, one convenient way to go from larger to smaller tubing without any NPT or glued fittings is a part called a “barbed reducer”!3/4 barbed.
What’s the advantage of the hardline over soft? I thought the soft would allow more vibration absorption. And my pump is to the right so if it was a hardline I’d need two elbows I think.No worries, so the waterbox soft line is 3/4 ID? it does not fit on the barb at all correct?Sorry I misspoke. The Waterbox comes down to a 3/4.
Personally, i always swap out fittings and hard plumb the return (using a few unions so i can easily take the return pump out for maint.) I've not had a waterbox so i cant say what it will take to do this though.
This thread might help if you wanted to hard plumb it : https://www.reef2reef.com/threads/need-help-with-hard-plumbing-return-on-waterbox-reef-100-3.885456/
this has pipe threads on one side; will they match the threads on the pump?I grabbed this in hopes to reduce the out on the pump and use the soft tube the Waterbox came from to link.
https://www.bulkreefsupply.com/schedule-80-straight-reducing-barb-x-male-thread-1.html
I hope so. Someone on Reddit pointed me in this direction. Why do you need to know plumbing to hook up a return pump?this has pipe threads on one side; will they match the threads on the pump?I grabbed this in hopes to reduce the out on the pump and use the soft tube the Waterbox came from to link.
https://www.bulkreefsupply.com/schedule-80-straight-reducing-barb-x-male-thread-1.html


You’ll be able to tell by unscrewing the factory barbed fitting, and seeing if there’s a rubber sealing ring between the fitting and the pump body!I hope so. Someone on Reddit pointed me in this direction. Why do you need to know plumbing to hook up a return pump?![]()
Its just personal preference. I run a manifold directly off the return. If new to the hobby and plumbing in general, soft is the easiest way to go.What’s the advantage of the hardline over soft? I thought the soft would allow more vibration absorption. And my pump is to the right so if it was a hardline I’d need two elbows I think.