Plumbing help - stepping up or down?

I ordered the Whale Gulper IC for my forward head, and it arrived today. I've looked through the manual and I understand installation, it's pretty straight forward. However I have an issue with the two way manifold.

My sink, and shower (2 drains), all connect to one hose via PVC tee's. So I have a 1" or 1 1/4"ID hose coming from those drains. The other line that I have is a 3/4" coming from my A/C condensation pan.

The two way manifold on the Whale isn't threaded, so how do I step up to the larger hose size from the shower, and step down to the smaller A/C line? I know I'm going to need some kind of barb fitting, I just don't know what's the best option.

I used double male step up fittings, West Marine carries them. Not the most elegant solution as it uses a lot of hose clamps, but works fine. I also used elbows in the hoses where needed rather than trying to bend them.

So male to male barbs, and hose splicing.

That was my original thought, but hoped I could get around that somehow.

I though I saw fittings on a Whale pump that had stepped inlet / outlet that let you cut off the smaller dia portion if you needed a larger size. I'm pretty sure that's how they configure their shower dumps. Check to see if you can get a T w similar steps?
How about...
A threaded female thread reducing Tee with Male thread to barb fittings? Even if you need a thread bushing its compact and neat and only needs clamps on each hose?

https://www.westmarine.com/buy/mari...hose-manifolds--P011_332_002_508?recordNum=33

https://www.ebay.co.uk/itm/20239828...0943b7216b0a688fa162cf6fff16006&ul_noapp=true

While I not exactly clear what you have, the pvc pipe fittings can be your answer. Start with the largest hose, let's say it's 1 1/4". Buy a tee that's 1 1/4" and adapt it to hose barb for the shower. Buy a bushing to reduce the tee to 3/4" and add a hose barb to that for the AC. Finally, bush the last outlet of the tee to the size for the pump and add the hose barb to that. Lowes usually has the best selection of pvc fittings. The tees and bushings are available in glued or threaded. Threaded may be better for this application as the hose barbs are generally threaded.

Ted

This is what I have...

Hello there .you can buy multiple different sizes which are called Menders. which is Barb to Barb that go from 3/4 to 1 or whatever size you need it to step up or down. the one thing you do not want to do is step down to a through-hul. will guarantee you get a blockage at some point in the future unless it is just clear water passing through