Setting up a Jumbert system

[goodreef]

In a pure Jumbert system, I need to have a plenum, 4 inches of 2-5mm grain sand, and minimum rocks touching the sand bed. I've got the first 2 points covered, but the 3rd point is really difficult!!!

From what I've researched, I'm suppose to prop up the live rocks with PVC pipes. This way, water can easily flow around the PVC pipes, and detritus are not pushed into the sandbed.

However, setting this up is a killer.

WHAT I PLAN TO DO ...

1. Using 2 inches diameter PVC pipes, I will cut each to a length of about 6 inches. I plan to have 4 inches of PVC inside the sand, and 2 inches sticking out of the sand to support the rocks.

2. For each of the 6 inches length of PVC pipes, I will drill many big holes on 4 inches length, and leave no holes on the 2 inches part. When I stick the PVC pipes into the sand later, only the portion in the sand will have holes. The top portion will not have any holes. This way, within the sandbed, water can easily diffuse into and out of the PVC pipes through the holes. However, above the sandbed, water cannot easily move in and out of the dead space inside the PVC pipes. Though this creates a permanent dead space in the PVC pipes, it also limits the accumulation of detritus inside the pipe. An added bonus is that Pods are protected inside these pipes.

3. After setting up the plenum and filling up with 2 inches of sand, I will push the PVC pipes into position. A netting is placed on top of the sand, and 2 more inches of sand is placed on top. Check to make sure that the sand level inside and outside the pipes MUST be about the same.

4. Small holes are drilled on the PVC end caps, and fitted to the TOP end of the PVC pipe. This way, pods can easily move in and out without being eaten. Also, this really limites the detritus accumulation inside the pipes.

5. Rocks are arranged on top of the PVC pipes.

6. A wave maker is used to make sure that there are no dead spots between the sandbed and the rocks.

Potential issues with the above ...

1. With this design, there will be dead spots inside the PVC pipes. Yes, water can still diffuse through the top cap of the pipe, and at the bottom of the sandbed. That's it. Anyone feel that this will be an issue later??

2. If all the 2 inches diameter PVC pipes are stand-alone and not connected to any main structure, do you think that the entire rock structure above will collapse after some time?? Afterall, 4 inches of the PVC pipe is burried inside the sandbed, and only 2 inches will be above the sand bed. Also, I assume that the pressure from the weight of the rocks will be downwards, making the overall structure even more stable?? Any engineers can help??

3. Any obvious design flaws??

Please comment. Thanks!!!