I've been wanting to do something that looked like it came from a mad scientist's lab so a few months ago I started looking on ebay for laboratory equipment. I found two quadruple neck boiling flasks (12L and 5L) and cork rings to set them on. I've seen one or two other boiling flask aquariums on stempunk sites but I've never seen two separate spheres linked together. I decided to try using a parallel distillation connecting adapter but I'd either need to run a vinyl hose through it or connect some acrylic tubing so that I could create a siphon. This has been the most difficult part of this project. It was a lesson in fluid mechanics/hydraulics as I had to balance the output from the filter into the 12L against the input to the pump from the 5L. If it was off then the 5L level dropped and the 12L overflowed. I finally found through trial and error that the minimum diameter tubing between the two had to be at least 5/8" I.D. The tubing to the Zoomed 501 pump is 3/8" I.D. I ended up having to use silicone rubber to glue acrylic tubes onto each end of the distillation connector.
I currently have Azoo substrate, some Hornwort, and some Nerite snails in them. I'm using a Catalina 50W titanium heater in the 5L flask and I have an ADA glass feeder in one of the necks of the 12L. I'm using ground glass connectors wherever possible to maintain the laboratory look.
Two of the nerites decided to attempt to clean the inside of the connecting tube and caused my 12L to overflow about a liter of water before I saw it so I had to cover the tube with an intake cover I found at the LFS. I'm using one of h4n's 9mm stainless steel guards on the filter intake in the 5L tank in case I want to add any shrimp to it.
I also wanted to have submerged lighting in the main center neck of each flask.
I looked in vain for lab equipment that would be small enough to fit into the neck, not fall through, and be large enough to accommodate LED's. I contacted DP Glassblowing which I saw advertising custom chemistry glassware on [Ebay Link Removed] I told them what I was looking for and asked for an estimate. I got a reply asking my address, thinking they were going to give me shipping costs. They sent me two sets of the tubes I needed free of charge! I couldn't believe it. I've never had anyone so generous before.
Enough talk, here's some photos: