Told DCQuarterCircle I would post some pictures of my Matala diffuser base modifications and thought this thread is as good of place as any.
The Matala bases are nice, good quality plastic. They have a hole to fill them with sand for weight. All this works well.
The problem for me was placing them and being able to retrieve for maintenance. I wanted to be able to let them down with a rope, be able to move them if I did not like the placement, have a rope attached with buoy so they could be located in case they quit working, and be able to pull them out when needed.
The Matala bases had no place to attach a rope. I guess that is fine if you are placing them in the bottom of a dry pond.
I made nice bases out of 2x6 boards to attach to the bottom of the plastic base. Then I ran a rope through holes in the boards first cadi-corner then to all four corners. This worked but not very well. Putting buoyant wood on the bottom of a heavy item tends to make it want to turn over in the water. I got them down, but it was not easy to get them on the bottom without them turning upside down. But it worked for the first year.
My attempt this year was to add eye bolts to the wood, and attaching the ropes above the diffusers with the idea of changing the center of gravity. But I had removed the diffusers for the winter and the boards dried completely out, so they were even more buoyant. Still wanted to turn over and would barely sink. After getting one down that way, the other two decided to do something different.
The pictures below show the final attempt that worked excellent. The changes I made were to take the wood 2x6 structure off and replace it with 15"x20" nylon kitchen cutting board. Not wanting to repeat previous problems I also added the two eye bolts so the center of gravity would be lowered. I also drilled small holes in the Matala plastic base at the upper and lower part to let air out and water in more quickly while trying to sink (they are already full of gravel).
Worked like a charm. Stayed upright and level and easily was able to let the diffuser down to the bottom. Now they can be pulled up for cleaning or other maintenance easily. The cutting board also makes for a larger base so it will not sink into the bottom as far.
The rope attached has a float on the surface so I can easily locate the diffusers and lift them onto my boat if/when needed.
