I got my Vertex Diffusers from Hoosier Pond Pros (the business owner, esshup, is a very active PB member)...

https://hoosierpondpros.com/

They have been in my pond for 4 or 5 years now and have performed very well. The ones I bought were just the head and needed to have the base added. Here's a thread with a few ideas...

https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=525288

I used concrete and have since added an eyebolt to the concrete base to pull it up from the bottom. Originally, I tied the rope to the pvc plumbing and I was afraid of breaking the plastic pipe works.

I also bought my weighted line from there too.

Fish on!,
Noel