Filtration - Version 2
Why rebuild?
When I rebuilt the pond, I decided to rebuild the filter at the same time. The old filter worked fairly well, but there were several things that I did not like about it. Also, being an engineer, I just couldn't resist the temptation to tinker with the design. ;-)
- Pump Location - This was more an issue for the pond design, but it effects the filter as well. In the previous version, the pump sat on the bottom of the pond, and therefore picked up a lot more junk and became clogged easily. This had two effects on the filter. First, it had more sediment and debris that it had to deal with. Second, as the pump got clogged, the filter (and falls) got less flow. To correct this, I mounted the pump on a rigid pipe that holds it about 8" off the floor of the pond.
- Restricted Flow - The small diameter of the vinyl tubing that connected the pump to the filter, restricted the flow by adding to the dynamic head that the pump sees. The new falls were going to be slightly larger, and I wanted more flow through the filter and over the falls. To correct this, I went to a 1 1/4" PVC pipe to carry to water. This greatly increased the flow without having to buy a larger pump.
- Aeriation Tower Placement - The design of the tower and its placement made it difficult to get to the various parts of the filter for cleaning. It also was not a very stable connection from the pump to the tower. For this design, I wanted the tower to connect from outside the filter instead of down through the center, and I wanted the feed from the pump to be rigidly connected to the tower.
- Bio-filter Media - The lava rock turned out to be hard to clean, very heavy. Also, I have heard that it clogs easily and soon has much less surface area for the microbes to colonize. I decided this time to go with one of the comercial materials.
Design
(Click on picture for a full size version)
Most of the materials and construction techniques are the same as the first version, so look there for pictures of the filter itself. I still haven't taken any pictures of the current one.