Building A Jellyfish Tank From Scratch

Lacuna

New member
Hey everyone,

I'm currently in the process of creating a custom jellyfish aquarium, aesthetically based on the Cubic Pulse 80, as part of my bedroom redecoration. I'm about to strip out my whole room and put down wooden flooring, new furniture and all that good stuff, and the jelly tank is going to be the centrepiece. I'm buying a large corner desk and the tank will sit on the worktop, visible from the front and both sides.

So, why build one from scratch? Well, I've been looking at Cubic's range of jellyfish aquariums and while they look pretty cool, I'm not comfortable paying about £1200 for the whole setup. Plus, I wanted to add an additional viewport on the front panel so you can see in the tank from all around the room (apart form the back, of course). I am going to see if it's possible to build an all-in-one jellyfish aquarium which is just slightly smaller than the Pulse 80 (my design is WDH 250mmx600mmx500mm, compared to the Pulse 80's size of 270mmx600mmx600mm). The good thing is that I'm only planning on keeping 3 or 4 moon jellies at first, so the tank is way bigger than necessary. You can reportedly keep upto 100 moon jellyfish in a Pulse 80, so I'm expecting the capacity of this tank to be (at absolute maximum) around 80 juveniles, given that additional space is used in my design for control surface to help regulate their movement. You also have to bear in mind that 100 jellies would require greater water filtration to remove their waste (and a ton of food), so I can get away with using a very basic internal filter for now. The rear compartment is designed to fit a Fluval U1 internal filter, which will be more than sufficient for even tens of jellies. I will go into more detail on my filter choice further down.

As of writing this (13/6/16), I ordered all of the supplies today, and they are all being delivered tomorrow (with the exception of some additional clear perspex I need to order now, since I changed my lighting design after ordering the acrylic).

Before I go into more detail, here's a basic render to show the overall style of the tank and to list it's features. Note that there are hatches on top to access both the main tank and the filtration compartment, plus a side panel to access the lighting (under the filtration compartment). Please note that the render does not show the lighting change I made. I'll post an updated design later on which better shows the filtration and lighting systems.

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I notice that there are maybe 3 or 4 posts related to jellyfish per month on Reefcentral, so it's probably worth me explaining a couple of design constraints in case you're reading this but haven't looked at other jelly tanks before.

The main issue is water flow. The current must be regulated so that the jellyfish stay afloat and can swim around the tank, but do not become trapped anywhere. In the past, many jellyfish aquariums ended up with jellies being shredded in the tank's filters, which isn't what I'm going for. Luckily all of the modern tanks seem to be Kreisel tanks, which are tanks where the water is circulated around the tank in a circular motion. In my tank, this will be achieved with a half-submerged spraybar placed above the filter intake. When the jellyfish get near the filter, the current from the spraybar will push them down to the bottom of the tank. The current from the filter intake will control the horizontal flow, therefore creating a circular current throughout the tank.

Other considerations are salinity, pH and temperature, but this isn't really a part of the build. I will include the salinity of the water in the journal once I get around to actually filling the thing up, but aside from that these are environmental. Some people would recommend a chiller but I live in the UK, so there really isn't much risk of a nice day. My ambient room temperature is typically around 21 or 22 degrees Celsius, which means I can control it either side (depending on the species) with my own heating. It's not the best plan for temperature regulation but nothing extravagant is needed here, given that the ambient temperature will be about right for most species anyway. If it turns out that I need to keep the temperature down a little then it will be easy enough to make a fan-based chiller, some simple radiator fins mixed with a couple of fans to pull heat from the filtration area (I always have plenty of PC stuff lying about the place, especially fans) If you live closer to the equator, I'd imagine a chiller with a temperature you can set would be necessary.

Maintenance and feeding will be optimal with the large ceiling hatch as I'll be able to get my arm in to the tank without any trouble. I plan on feeding the jellies a diet of Cubic Medusa, a balanced food specifically for jellies in home aquariums. On paper, this thing should work out pretty well.

But for now, I'll go over the tank in more detail. The lighting system I mentioned earlier consists of a single LED lamp, approximately 12cmx8cm, which will sit around halfway up the tank behind a perspex sheet. Again, the lighting section is below the filter system, so the bottom half of the back section will be used to house the light and it's wiring. It comes with a remote-controlled remote so I can instantly change the look of the tank. While reading through other forum posts, I came across some concerns that this confuses the jellyfish, and that it can damage them. This, at least as far as moon jellyfish go, is completely false. They lack the organs capable of distinguishing between colours, which some jellies do have. Therefore, the colour has no effect on them but will have a great effect on the surroundings; moon jellyfish reflect colour due to their translucent structure and so they will appear to glow the same colour as the lighting. I am looking forward to seeing how this turns out in the final build.

I'll be posting updates as I go, with images of my progress. I'm hoping to cut the main acrylic shapes tomorrow so I can begin assembling the exterior as soon as possible. The biggest problem I can see is bending the acrylic. I need to create a jig which will allow me to create curves to match the radial curves of the side windows. I also need to bend these curves into additional sheets to cover the filter and to place at the bottom back of the tank. Acrylic heat bending aside, I'm confident that this build will go more or less as planned. I'm looking forward to sharing this with everyone- please leave me your thoughts or let me know if you have any questions :)
 
Well, everything arrived but the geniuses down at the plastics place apparently thought that black was the same as clear perspex. I spoke to a girl on their sales team and she had me email the invoice number in, and said they will sort it out ASAP. With any luck I'll be able to get the rest by tomorrow.

Today I'm planning on cutting the holes out for the lid and making their perches so they have something to rest on. The floor is already finished as it's a simple sheet of acrylic, as is the rear panel. I'll post an update later on with my progress.
 
There wasn't much I could do this morning, but I thought I'd make a start. Instead of starting with the roof, I cut out the holes for the light and the outflow. I've changed the lighting setup slightly, so instead of sitting behind perspex, the front of the lamp will actually be exposed in the tank. It's already a fully waterproofed LED setup, but I'll be sealing it once everything is together to make sure it's impossible for any water to get where it shouldn't. I had a couple of problems with cementing the back panel to the floor panel because of the size of the things (our garage is on a very slight incline so they kept toppling over after a little while). I had to put together a makeshift jig to keep them both at right angles to one another, and that's curing now. Tomorrow I will see how the join turned out and if it's strong then I'll cement the middle panel (with the holes cut into it) 10cm in front of the back panel, using a similar setup to hold it in place.

Now, I don't think the perspex is going to be getting here tomorrow. I've received 3 or 4 emails off the "support team" at the plastics place but it's not going great so far. Initially I got a response back pretty fast, apologising and telling me that more would be cut and I'd get an email once they're ready.

When I came back inside, I had another email from the acrylic suppliers saying that I should disregard the first email, as they had read through my order (probably would have helped if they'd bothered reading it yesterday), and that I had in fact ordered it in black. I had the order form from yesterday to prove that I was right, so I forwarded it to them and also sent a screenshot highlighting where in my order it clearly stated that I had ordered 2 480x480x10mm clear perspex sheets. I haven't heard back from them since.

This might go on for a couple of days but I'm sure I'll be able to get them replaced soon enough. In the meantime I need to think of the best way to make a clean lid for the compartments. I was going to cut holes and have them resting on perches, but it will probably look better if I just slice off a whole section for each lid so you can remove the whole top. Not only would it be better for accessing the tank, I'm using a handheld jigsaw to cut the acrylic so the cuts aren't exactly the cleanest. Luckily it doesn't matter with the overflow or the light as these are hidden, however I'll need to make sure they're as neat as possible for the exterior cuts. Also, I did plan for this, so I made the cuts just inside of my measurements so it'll be easy to sand them down to where I want them later on.
 
The clear perspex will be here today, and I get to keep the old stuff for free (just under 1m^2 of 10mm black acrylic)- it's nice to have some extra in case I need to reinforce anything. I also have a 180mm tube coming on Friday which will let me mold the corners to the perfect radius. I should be able to simply heat the acrylic and then overlay it onto the pipe and smooth it over, which will save a lot of time if it works properly. I'll be testing this out as soon as it arrives.
 
Well...

I'm now having trouble with DHL. Their £25 overnight service is now 2 days late and apparently it's been delivered and signed for. I didn't get anything. They're looking into it and I'll know what's happened (lazy driver I'm assuming) by 12:00 PM on Monday.

In the meantime, a lot more stuff has arrived. I'm swapping out the rather ugly lighting system for an inline LED strip, IP68 waterproof standard so it's fine to have it submerged in the tank. It's RGB and I've hooked it up to an IR remote control and it's working great. So the lighting will now be even more robust- it even includes randomised sequences so the tank will be able to transition seamlessly from one theme to another.

I had some fine foam pads delivered (pond filter grade) to cover the outflow to minimise the food which reaches the filter. Should help to keep stress off the filtration system. I also swapped out the 4mm airline for 10mm silicon tubing so I can simply run it up to the top and make a small acrylic endcap to attach it to the 20mm PVC tube (the spraybar).

I am hoping to buy a bandsaw tomorrow (found one on Gumtree in my area, fingers crossed the guy gets back to me soon) so I can get all of the cuts perfect. I managed to cut with the handheld jigsaw and file it down but they really aren't built for accuracy. I need to make sure everything fits very snugly or else it's going to look shoddy. It's not even a matter of waterproofing- the sealants I have will cover gaps of upto 1mm- but I'm trying to make this look as high-quality as possible.

Also, I realise I haven't posted any actual pics yet but there really isn't too much to show. This first week has revolved around sourcing parts for the tank, and as soon as I have all of the tools I'll be able to get down to it. With the bandsaw, I'll probably have the tank built in a week or so, depending on my schedule.
 
Gumtree guy replied- going to pick up the bandsaw sometime today. This will make everything a lot neater.
 
I'm still waiting on the clear perspex (they said it will be here by Friday at the very latest) but I've made good progress. There have been some significant changes because of structural considerations and the fact that bending the acrylic is almost impossible to get right (and it needs to be perfect or else the tank won't fit together). I've decided to remove the exterior curves altogether and make the tank a cuboid. Four clear inserts will sit inside the tank to provide the curves needed to protect the jellies. The four inserts are cut and almost ready- I just need to remove 2cm off the end of each of them before they can be used in the tank.

I've assembled the filtration box- all 4 sides are up and attached to the base. The front panel is attached and two runners connect everything at the top. There is a loose panel which sits on top to act as a large lid. It will be very easy to access the internals.

I've cut the new channel for the LEDs to sit in. Once the clear perspex arrives I'm going to use the leftovers to create a cover for the lead channel to make sure that no water goes through that way (or else it won't be filtered properly). I've also made two brackets which will hold the LEDs in place behind the channel (those are attached to the tank and drying as of typing this).

I have £40 worth of high-quality bioballs arriving tomorrow. I'm going to cut a divider for the filter- the filter box will be split into two sections, with a gap at the bottom, so the water has to travel down to the bottom and back up the other side before reaching the filter. When entering the box, the water will pass through a foam filter pad, before going down into the pit of bioballs. It will then go through the filter itself as the final filtration stage, before travelling to the spraybar and being circulated back around the tank.

While it's not as fancy without the curves, I do have to say that it's looking pretty damn good so far. I'll try to get some pics up tomorrow. The more squared shape will certainly be a lot stronger than the original design, and it's slightly more compact so it will fit on my desk better too. The volume will be just under 60 litres when full.
 
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Bioballs are here. There are just under 2 litres of these things so it will really help with breaking down ammonia in the aquarium. I'm going to cut the divider for the filter later on today and get it fitted (after sealing the bottom of the filter box), then I can place the balls and the filter in to see how much space everything takes up. I'll probably make the pad holder today as well- there will simply be 4 perches in the first half of the filter on top of which a foam pad will sit to catch the largest particles.

All that will be left after that will be fitting the windows (when they get here), sealing the rest of the tank and making the spraybar. I think I'll be cutting a PVC pipe to the interior width of the tank so you'll actually be able to see inside the spraybar from each window. Then I'll just cut a hole into the back of the pipe and secure the inflow pipe from the filter to that.
 
Please excuse the mess of both my room and the tank itself- I'm completely remodelling my bedroom so I figured I'd finish the tank in there. The tank is pretty dirty on account of the sealant gun not fully reaching all the required angles in the tank. I ended up having to put sealant on my fingers and run it along the edges by hand, which covered everything but left a lot of mistake areas. After it's all fully cured, I'll be cleaning it up. Also note that the way the lid isn't flush with the top at the back end of the tank- this is because of the LED slot I cut at the back. I need to file it down a little more (again, after everything has cured), and that will fix the problem.

Also, in this image the tank doesn't exactly look sturdy, but in actuality none of the panels budge at all. It's very strong and should be more than capable of holding the weight of 60 litres of water.

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All that's left to do now is drill the intake holes, fit the four curved inserts (they need cutting down slightly) and get the spraybar set up. I've already created the bar itself- a 20mm PVC pipe just slightly shorter than the inside of the tank, with outflow holes drilled across it at even intervals.

The tank has taken me a lot longer than expected due to the various shipping delays and the fact that I've been very busy, but it's almost finished now. I'm planning on starting a journal of the tank's usage, so if you're interested you can find out how well the tank is serving it's purpose and if the jellies are doing well in the setup.
 
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Did a test of the sealant and the tank is fully waterproof. Nice to know before moving on. Filling it with water also rinsed off most of the rubbish and it looks a lot neater now. I was able to tip it towards it's front to empty out 60 litres of water and the weight of it didn't budge the front panel, so it's safe to say that it's sturdy enough for usage now. Almost there now (I'm very busy today or else I'd have it finished tonight).
 
I've been so busy this past week that I barely had any time to work on the tank. I have pretty much finished decorating my bedroom now which took up a couple of days last week, and aside from that I ended up with tons of work to do. I was free today (mostly) so I went ahead and grabbed some pics of what I've been up to, which show how the tank looks in the room and showcases some of the features.

First up, the tank after I cleaned it some more and double-sealed the thinnest areas. I am covering the joins with black gorilla tape (arriving tomorrow) so you con't be able to see the sealant at all. Admittedly I made quite a mess of the edges but the sealant doesn't come out like standard ones and is very difficult to apply neatly. Although I'm pleased with it for my first build :)

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The spraybar is now securely attached to the filter and everything is sealed so the water has to follow the path I want it to. The tubing is 10mm silicone and the spraybar is a 20mm PVC pipe. The pipe is the perfect width to fit between the two windows of the tank. Here it was while curing:

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I grabbed this a couple of days back, before I finished decorating. It shows the first stage of the filtration system- a triple-layer mechanical filter which increases in density from top to bottom. This is to catch any large particulates such as food to keep them out of the main unit.

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Here you can see how the tank sits on my desk. The LEDs used in the room are the same as the ones in the tank (not turned on here, I am waiting for another connector to arrive tomorrow so I can power them both at the same time). The room and tank LEDs run on separate boxes, but are controlled by the same IR remote, and because of the positioning you can change their colours individually.

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I also grabbed a couple of shots of the extra equipment- a huge tub of marine salt so I can keep on top of water changes and a refractometer for accurate salinity recordings.

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And that's just about it for now. Tomorrow I'm going to (finally) cut the inserts down to the right length and get them secured in place, plus I will be drilling outflow holes and a 10mm hole for the spraybar inflow pipe into one of the four pieces. I will be filling the tank up with water again tomorrow and washing everything out (I drilled the outflow holes in the separator panel so there is a lot of loose material in the bottom), and then I can test out the water flow. Fingers crossed I will have it completed tomorrow night.
 
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