Again, trying to keep costs to a minimum I went to a local sign making company and purchased scrap 1/4" plastic to create an insertable plastic box to fit down inside the 20 gallon aquarium I was using for a sump.

The bubble trap would provide an area for the return from the display tank, and a place for my skimmer, along with an area for a suspended bag of carbon, some foam filter material and a 9" by 8" refugium area for caulerpa, some rock and whatever managed to make it's way into the sump.

I cut the plastic using a jigsaw with metal cutting blades. One of the problems I had with cutting the pieces involved heat from the blade causing the sheets to melt back together as fast as I could cut them. I ended up using a back and forth cutting motion to create a seam that could be broken by hand. Look below for an overall view of the sump,

and how the bubble trap fits into the scheme of things. The grey tube on the right is the hang on skimmer, and the position of the foam filters, carbon bag and SEN 900 return pump is also indicated.

The pieces were glued together using acrylic glue that I purchased at the sign company, and they were sealed using aquarium sealant that I purchased at a local pet store.

Current in the refugium is a bit high, and I've added some coarser aragonite and crushed coral to keep the Home Depot sand from blowing around. An overhead diagram is shown below, indicating the position of the two 250 watt heaters.