While shopping in a petstore the other day, I noticed they were offering a cool cylindrical aquarium. A black tower is partially attached to the tank, which allows you to hide a traditional hang-on-the-back style filter. LED lights in white and blue were included with the tank as well.
The price was really good ($69) so I picked it up. Once I got it home, I immediately began to dissect the tank and figure out how I could make it jelly safe. The hang on power filter couldn't be used, at least not if the intake was put directly inside the aquarium. I also noticed the black back tower was attached to the aquarium by setting it into the stand. It was by no means water tight, however. I thought I would start by siliconing the back tower onto the tank. I could make it into a filter chamber.
A few problems came up though. The cables that power the lights and filter ran through the tower. At the base of the tower is a master switch that controls everything. I would need to glue a piece of plastic over these components, so they aren't submerged or exposed to water at all. Secondly, I would need to drill holes into the back of the actual tank so that water can flow into the new filter chamber. Thirdly, I noticed the filter was hardwired into the lights. The AC power adapter first connects to the filter, then the wire runs out of the filter and can be plugged into the lights.
The first issue was easy enough to solve. The tank comes with a little black panel that you are supposed to attach to the tower so it can cover up the filter for aesthetically reasons. This little panel has two grooves on either side that allow it to slide up the tower. If you cut these grooves off, the panel fits snug inside the tower. I chose a spot about 2.5 inches above the switch and glued the panel in with silicone. A rubber band around the entire tower helps to keep everything in place. I also used super glue to make sure the weight of the water wouldn't cause the silicone to fail.
I decided at this point, I had no use for the filter. I cut its two wires off. If you are good with electronics you can strip an old AC adapter and save the filter. You should be left with a stripped AC adapter and a wire with a LED connector at one end. Strip both wires and merge them. Use heat shrink tubing or electrical tape to cover the exposed wires, and you should be good to go. I drilled a small hole in the tower near the switch so I could feed the internal wires out. Then you can attach the two LED wires from the lid down to the wires that were fed through the tower. Plug the adapter into the input wire. This should have allowed you to successfully omit the filter.
At this point, I had the tank drilled out, and the back cover glued in permanently. The holes allow water to pass freely into the tower chamber. I plan on putting a Tetra Whisper Filter in this chamber. It will draw water in and then overflow it into the tank. Using some paper towel shreds as test jellyfish, I noted that the flow on the holes didn't seem to be high at all. That's good, as the jellies shouldn't get caught on the holes.
This modification was a little bit of work, and kind of redundant, but it produced a nice tank. The advantage of a tank like this is that it has actual filtration. Other cylindrical jellyfish tanks generally use air powered under gravel filtration. That works, but isn't terribly efficient. This filtration system will allow a better efficiency. I'm thinking the tank can hold Moon jellyfish, Blubber jellyfish, Lagoon jellyfish, Upside Down jellyfish, small Sea Nettles etc. I will probably test it with Moon jellyfish soon.