DIY Jellyfish tank!

Here I’m going to show you how to make a quick and cheap jellyfish tank that is great for catching your ephyrae from your polyp bank and even growing the ephyrae up. Obviously this isn’t a display tank, but it’s great for holding and growing your jellies until they are big enough to display. If you build several of these you can distribute your ephyrae between them to achieve greater size before going into the display tank…

You are going to need a few things before we get started:

  • Some type of rectangular or square container, a Critter Keeper, acrylic tank or even a Tupperware storage bin which is what I have chosen to use for this project.
  • Painter’s tape
  • Scissors
  • Nylon screening, I used a 150 micron sized mesh for this, found here at Aquatic Eco-Systems.
  • Silicone, I prefer Dow Corning 999-A, but you can use almost any silicone. Just make sure its not for roofing or concrete work. I find it easiest to work with clear silicone so I can see bubbles.
  • Bulkhead/PVC tank adapter, 3/4″ is going to work for most of you. For larger applications you may want to use 1″.
  • A cup of ice cubes
  • Disposable gloves, even though I didn’t wear any for this project, I recommend wearing them.
  • A well ventilated space if you do not enjoy the smell of silicone

Step #1

Save the lid! If you chose a Tupperware container like me, keep the lid. You are going to want to use the lid to control evaporation, hold your incoming water lines and help keep the structural integrity of the container.

You can find these at Home Depot for a few bucks when they are on sale.

Step #2

Install your bulkhead, no I’m not going to go over this, but do remember that the gasket goes on the wet side! Backwards tank adapter = leak.

Gasket goes on the inside!

Step #3

Tape off where your screen will attach to the sides. You’ll want to leave some space so the screen does not suck up against the bulkhead. Cut your screen material to match your taped lines, you will want to leave a half inch extra on each side to allow for a nice curved screen. You can also use some rough grit sand paper to rough up the area behind the tape (everywhere silicone will go) in order to help the silicone hold onto the plastic.

Step #4

Lay a nice thick bead of silicone along each tape edge as shown. Now use an ice cube or your finger if you are wearing disposable gloves to smooth and flatten the bead. Some people spit on their finger to smooth the silicone, ends up smelling nasty though! Saliva + acetic acid, yuk!

Step #5

Do the other side, should look like this.

Step #6

Lay the screening on your silicone. Don’t worry if your screening is wrinkled, we’ll straighten that out later.

Step #7

Lay another bead of silicone on top of the screen and flatten/smooth with an ice cube again. Put enough pressure on the silicone that you can see it work its way down into the mesh, this will provide a strong bond. It’s ok if the silicone spreads over the tape, we’re going to peel the tape off later.

Step #8

Now we need to glue the bottom of the screen down. This is the trickiest part, especially if your Tupperware container has an uneven bottom like mine does. We are going to fill in that uneven part with silicone.

You will want to lay enough silicone down that it gets behind the screen and acts as support structure.

Again, use an ice cube to smooth all this silicone out. Its important that its smooth, you don't want ephyrae getting stuck in little pits.

Step #9

Use this time, while the silicone is still workable, to shift the screen any direction you like. Sometimes you’ll see an angled side or a bubble that needs to be pushed in. Or maybe the bottom of the screen isn’t a perfect curve, you can use your finger or an ice cube to smooth it all out again. What you don’t want to do here is move the screen until it is taught, if the screen is taught it can tear off the wall when you fill the container with water due to the plastic flexing. When you’re satisfied with your work, go ahead and peel off the painter’s tape.

Pull nice and slow.

It should look something like this when you’re done…

Last Step!

Don’t like that crinkled screen? Not to worry, simply wet it with those ice cubes or just some water and leave the container on its side to dry. The water weight on the screen will help re-shape the mesh. Sometimes mesh is too old or bent to re-shape which is why you should use new nylon screening. Also, the larger the container, the harder it will be to keep a nice curved screen. You can add support rods if you really want to. Sometimes if I have a screen that is sagging down in the middle I will insert a zip tie to hold it upright.

That's a little better, once it's underwater it should hold up ok.

Now leave it to dry for 24 hours!

Did you get some silicone somewhere you didn’t want to? Leave it alone! And once it dries, then remove it. Smearing it will make it difficult to remove.



About Wyatt

I am a professional jellyfish aquarist in the public aquarium industry. I have worked in marine animal husbandry since the age of 17, it was my first job. I love raising jellyfish, especially new species, and finding better ways of caring for them. Here, I hope to provide great ideas and product suggestions to help you create your own successful jellyfish displays.
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8 Responses to DIY Jellyfish tank!

  1. Travis Brandwood says:

    Thaks for posting this!

  2. This is such an informative article. The do it yourself jellyfish tank procedures is really helpful for those owners who wants to save money, but I I would prefer to get a service aquarium designer.

  3. JT says:

    great idea for a behind the scenes tank. i am interested in possibly building my own jellyfish tank, and was wondering if you had any thoughts or references. I was thinking the tank would be a little bigger than a table top display. i am fairly handy at building things. do you have any suggestions?

  4. Ash says:

    For my marine biology project I am going to build a tank for a moon jellyfish. Do you know where I could get the acrylic and what would be the best inexpensive way to build the tank?

    • Wyatt says:

      Hi Ash,
      McMaster-Carr is always a good place to get small sheets of optically clear acrylic:
      You could also try to find scrap or recycled acrylic at a second/last chance mercantile type place, usually at the town dump. You are going to want to study up on how to properly score, cut, bend and glue acrylic. There are many instructional videos on YouTube you can check out. I suggest you start out with a 12″ diameter pseudo-kreisel, so that’s an 18.8″ half-circumference and then add maybe 5 inches to each side to allow room for a screen. Good luck and let me know how it goes…

  5. Angel says:

    I have just started with jellyfish and I cant seem to keep the tank clean enough. I do weekly and monthly partial water changes but its still not as clear as I think it should be. Is their any type of filtration system you can safely use with jellys?

    • Wyatt says:

      Hi Angel,
      How much water are you changing? Try to aim for 100% changed out over the course of a month, so 25% minimum per week. If that doesn’t do it then I would start with some bioballs or other biological filtration substrate, zeolite is nice. I do not recommend carbon media, unless it is super washed or on a larger system, because the fine dust has caused several instances where folks have lost their entire tank of jellies when the dust particles get trapped on and inside the jelly.

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