That’s not a pump, it’s just the regular drain thing, I have one of those that came with the bed.
I also read that once you get a lot of the water out from siphoning, that you can hook up a wet/dry vac (which I have) and suck the water out of the baffles, so I’m going to give that a try.
There’s also this, but I can’t imagine it would have any kind of effect on getting the water out of the baffles. Have you tried?
https://www.homedepot.com/p/Water-Source-200-GPH-Drill-Pump-DRP-1/203449537
It is a pump.
ETA: run it, and feel the vacuum it generates.
You can call it a pump, but it’s not really, look:
https://www.walmart.com/ip/Waterbed-FILL-AND-DRAIN-KIT-Blue-Magic/344396609
Same thing, comes with every waterbed fill and drain kit. I’ve used them in the past for beds that don’t have the baffles in them to make them waveless. The issue is getting th water out of the baffles.
A slight hijack. But very funny,
A long time ago, before cel phone videos. My friend, Mike, was moving downstairs.
And he thought, “Why drain it”? “Just have to fill it again”. “Let’s just roll it down the stairs”.
This did not turn out well. A video would be priceless!
Look, I had a waterbed for years, and an aspiratior like that was able to suck the mattress flat, even with a fiber pad inside. A pump isn’t going to get you any more vacuum, although it might be faster.
Ok thank you - I’ll let you know how we make out 
Make sure there are no air leaks in the connection from the aspirator to the waterbed - you want to pull a good vacuum. Test the waterbed end of the hose with your hand - you should feel a decent suction.