I just found this excellent DIY
Venturi! “Don W” from Reef Frontiers originally posted his made from acrylic rod. I couldn’t find acrylic rod so I made mine out of PVC
filled with a 2-part material from www.sanitred.com
called Quick Patch. I simply mixed it, poured it into a piece of ¾” PVC
and it cured solid in less than 2 min. Popped it into a lathe and drilled it with a tapered drill bit from both sides.
The coolest thing is that you can make a venturi out of any inlet fitting that comes with your pump; like a barbed fitting or even a worthless venturi.
This is the very best venturi I have ever used. It certainly beats any venturi that comes with a pump. These things are so easy to make you can make smaller or bigger ones and it only takes about 10 min to make.
Here are my pics:
Don W from Reef Frontiers: