I have some bad news on the cannonball jellyfish. Something contaminated the 200 gallon tank, and caused some damage to the cannonballs. They began to slow down the 3rd day of living in the tank. On the fourth day, they were motionless. The water and even the jellyfish smelled fine. All jellyfish are known for decaying extremely fast. You can check to see if they are dead or just not pulsing by the way they smell. I decided that I would move these jellyfish into my 30 gallon saltwater tank (Non jellyfish tank). Immediately the jellyfish began to twitch and eventually started pulsing again. I kept them in a net while we tried to track down the issue in the 200 gallon. All the parameters were assessed. They all seemed fine except for pH. We adjusted that, but found it did not help. The jellies would stop, as if frozen when placed in the tank. After thinking about things, we eventually decided the problem must be copper. Twice now, i have had LED lights fall into the tank and fry. The first time my LED lights fell into the tank, the jellyfish died. It was unclear as to whether their muscles were damaged from electrical shock, or copper posioning. I dosed the tank with Amquel, which is advertised as removing metals. The second time the lights fell in, I also dosed the tank, and assumed all was well. After dosing with Amquel we even tried a different product, Novaqua. Obviously neither product helped remove our copper problem.
In order to save the jellies, I converted the 30 gallon into a temporary cannonball jellyfish tank. I removed all the live rock, and anything that had sharp edges. The result was a sand bed and some macro algae. I let the jellies go into the tank. After watching them for a while, I assumed it was safe to add a small hang-on in tank filter. The next morning I woke up to find a jellyfish stuck to the filter. Over time its flesh seeped into the filter and formed into the shape of the protective grid. The jellyfish was dead by the time I woke up, but after spending a good 5 minutes working it out of the filter, I found myself with a handful of jellyfish chunks. I decided that I would need better way of filtering the tank.
I took a cooler, and attached a flexible hose to the drain at the bottom. All of the live rock, hermit crabs, snails etc. were placed inside the cooler. Water was then added to fill it up. I took a small fountain pump and used it to pump water into the cooler, and let water drain out of the cooler at the same rate. In a sense, I built a sort of reverse sump. Its pretty low grade, but seems to get the job done. Inside the sump i have three air hoses running, and the internal hang on filter.