Thank you for the feedback. Yes. The two membrane disk screw into the 3/4" pvc fittings on top. I had no idea that the inflated disks would do that. Do you have any idea what type of weight I would need? I could fill with concrete or change the lower pieces to 3" pvc.

Question. How much do you estimate the Vertex XL2 weighs with the sand inside it? Just thinking, I've got to be able to hoist this beast back up for cleaning occasionally don't I?

Do you know the dimensions of the Vertex base so that I can calculate the volume of sand and compare to the volume my unit will hold?

Thanks again for your great insight,

Dean