Testing
Next, we used various-sized pipes inserted within the LFOM to test the "pipe within the LFOM" theory. See the image below for a diagram of this setup. First, we tested a 3cm-diameter pipe by inserting it vertically into the 7.5cm-inner diameter LFOM. Second, we tested a 5cm pipe, and noticed that it produced a reduction of bubbles. After leaving the 5cm pipe in the LFOM for 5 minutes to ensure no overflow, we moved to test the 6cm pipe. This pipe also showed signs of reducing the amount of bubbles, so we left it in for 5 minutes as well to determine if it would overflow, which it eventually did.
Results and Discussion
With our initial test of the 3cm pipe, there was no noticeable change in the amount of bubbles formed under the LFOM. For the 5cm-diameter pipe we found a drastic reduction in the amount of bubbles formed under the LFOM. Keeping the pipe in for 5 minutes showed no signs of overflowing the LFOM or even raising the water level, so we can assume that 5cm is a possible solution. Finally, we tested a 6cm pipe for 5 minutes in the LFOM. We noticed that the water level outside the LFOM rose slowly throughout the 5 minutes until the water flowed over the top of the LFOM. This clearly meant that the 6cm pipe was too big, and was causing a backup of water within the LFOM. (When explaining these results, how are these helpful to the dimensions in an AguaClara plant at 6". If they are helpful, talk about how you would scale this.)
See the gallery on the retrofit designs main page for the photos documenting this test.