You may notice your jellies starting to curl up and move their bells in an erratic, clockwise or counter-clockwise rippling fashion instead of a normal pulse. We like to call this symptom “the Jellyfish Jig” and it indicates trouble in your tank.
The cause is linked to nerve damage in your jelly, which can arise is several ways.
-Your tank pH spiked suddenly: If you’re having pH problems in your tank, you have to adjust the chemistry slowly. If you add a ton of buffer or change too much carbon all at once, it may bring your pH up too quickly. Jellies always need to be acclimated to new conditions, even within the same system, so even though your goal is a pH of 8.0-8.2, you don’t want to get it there in a few minutes.
-Your jellies experienced sudden temperature change: If you took your jellies out of your tank for a major cleaning and dumped them right back in, or if you did your weekly change with some water from your refrigerator, that can have serious consequences for your jellies. Again, they require stable conditions to be happy and healthy. Always be mindful of temperature when your jellies are going to experience changes in their water.
-Your jellies’ food is too acidic: If you use shelf-stable jellyfish food, or you allow your frozen or refrigerated food to spoil, it can be highly toxic to your jellies. Live food is always best, frozen enriched food is a close second, but using anything below that in quality poses the risk of poisoning your system.
-Your jellies were stuck to the bottom or side of your tank for too long: If your tank flow is dialed down too low or your jellies are getting too big for their system, you may see them start to get stuck to the walls of their space like a suction cup. When this happens, they can no longer exchange nutrients and gases with their environment, so they will start to degrade. Not to mention, they will continue attempting to bell, which can lead to them pulling out their own oral arms. If you see them stuck to the sides or bottom, gently squirt some water at them with a clean turkey baster from a diagonal position to try and lift them off (be sure not to squirt all the water out because that can create problematic air bubbles). If that won’t work, gently nudge the edge of their bell with the end of the baster or another clean, rounded object.
In most cases, your jellies won’t be able to recover from this condition, but you can at least prevent it from happening to future jellies or any survivors.
Relocating? Need some help figuring out how & when to move the jellyfish?
First, there’s a couple things to keep in mind.
Time is of the essence. As you know, your jellies need a constant current of water, so it’s not good to keep them out of their tank for more than a day. For the same reason, it’s crucial that your tank has access to electricity to keep the pump running, so you can’t leave it in your new place before the utilities are sorted out. This process needs to happen as quickly as possible to ensure the safety of your jellies, so it’s probably a good idea to save the jellyfish tank for the last day of your move.
Your filter media needs to remain submerged and in the dark the entire time. You spent a whole month cycling your tank’s bacteria, but it only takes a couple hours to kill them off again if you let your filter media dry out or expose it to sunlight for too long. Make sure you have something to accommodate your bio balls and carbon filters, for example a large, sealable ziploc bag or watertight tupperware container, and something to keep them shaded, like a drawstring bag or even just a towel to wrap them in.
Once you set the tank up, it’s hard to move. Make sure you already have the location picked out for your tank in the new house so you only have to set it up once. You may want to review this guide to choose the right place for your tank.
And here’s a list of the supplies you’ll need:
Buckets or tubs, one or two big enough to hold the water in your tank, plus another bucket for a few gallons of extra new saltwater
2-3 gallons of newly mixed/purchased saltwater to add to your system while you’re setting it back up
Large trash bags to line the bucket(s)
Zip ties to cinch the trash bags closed so the water doesn’t spill
Large ziploc bag or tupperware to store your bio filter media
Towels to keep you from ruining your new or old floors
Small cup for transferring jellies in and out of your tank
Level to make sure your tank is level in your new home
Alright, you’ve gathered your supplies, now you’re ready for the breakdown.
Step 1: Prepare the jellyfish transition container. Line a bucket or plastic tub with a trash bag, and begin to fill the bag with a few gallons of water from your tank.
Step 2: Transfer your jellies out of the tank. Unplug your tank, and gently move the jellies from your tank to your bucket using a small cup.
Step 3: Take the filter media out of the tank. Take the bio balls and carbon filters (and micron pad if you have one) out of your filter box and place them in a large ziploc bag or tupperware container. Fill the container with tank water and seal it for transportation, then wrap it in a towel or put it in a drawstring bag to keep it out of the sunlight.
Step 4: Get the rest of the water out of your tank. Fill the jellyfish bucket the rest of the way up with water, then fill another bag-lined bucket with the remaining water until your tank is empty. Now cinch your bags closed with zip ties, making sure to get ALL the air out of the bags. This way they don’t slosh around or spill in your vehicle, and your jellies won’t be harmed by air bubbles.
Step 5: Dry the inside of your tank. Give the interior a good wipe down with a towel to make sure it won’t get the inside of your vehicle wet. You may want to leave a towel in the display area and a towel in the sump just to soak up any extra water on the drive.
Step 6: Pack it up. Keep the drip tray, soffet, and lid separate from the tank so they don’t rattle around and scratch the acrylic. You may want to wrap the tank in a moving blanket to prevent scratching or other damage.
Now you’re at the new place, so it’s time to set it all back up.
Step 1: Place your tank in its new spot. Make sure it’s level before you add water, but keep in mind it may shift with the added weight of the water. If it’s not level, wedge a shim underneath it in the right places until it is. Keeping your tank level is essential.
Step 2: Add water and filter media to the tank. Take the water out of your no-jelly bucket and put it back in the tank, then keep filling it as close to the top as you can while keeping at least a couple gallons of water in the jelly bucket. Add your filter media back to the filter box, preferably using a clean mechanical filter to catch any gunk that may come out of your spray bars when you turn the pump on. Now fill the remainder of the tank with the few gallons of new saltwater you brought, keeping an eye on the sump level so as not to cause an overflow.
Step 3: Turn the pump on and wait. Now your tank is ready to be up and running again, so plug the pump back in and let the water cycle through for at least an hour before you add your jellies back. There will probably be some loose gunk from the plumbing or the biological filters floating in the system, which you can simply allow the mechanical filters to catch over time, or remove yourself with a turkey baster.
Step 4: “Burp” the air out of your tubing. As you add water back, air bubbles will start to form in your tubing and in your spray bars, which can harm your jellies if they make their way into the display area of your tank later. Give your tubing a gentle shake to loosen some bubbles, then give it a gentle squeeze to help push the bubbles out. Now move your finger under the top spray bar and push the bubbles out from underneath, and repeat the process until they’re gone.
Step 4: Acclimate your jellies. Even though your tank has mostly the same water as before, the new salt water you added may create a slight change in water temperature and/or chemistry that could potentially harm your jellies if you just dump them straight in. So just to be safe, perform 3-4 small water changes [roughly a cup (8oz)] over the course of half an hour once the water in your tank starts to clear up. Then you can gently add them back to your tank one by one with the cup you used earlier.
Step 5: Welcome your jellies to their new home! Sharing cake and balloons with loved ones is encouraged, but not necessary.
Low pH can have adverse effects on moon jellyfish over time, especially when it drops below 7.6. This problem is common in aquariums with filtration systems that don’t allow for adequate aeration or disturbance of water.
The optimal pH for moon jellyfish is 8.0-8.2. As pH lowers below this range, the water becomes more acidic and harbors excess carbon dioxide (CO₂). If prolonged, the lower-than-optimal pH can cause pitting in the bell, eversion, and bell shrinkage in jellies. Although moon jellyfish are commonly described as being “hardy” and “tolerant” of extreme water quality levels, too extreme can and will eventually cause them damage.
Filters that allow for splashing and rapid movement of water through them introduces oxygen to the system, keeping the pH up by steadily off-gassing that harmful CO₂. When filters are completely submerged in water, the rate at which the water is moving through them is little to none and can negatively affect both the water quality of your aquarium and the beneficial bacteria that you’ve worked so hard to grow during cycling. If the water isn’t moving through the filters, then the filters are doing nothing to clean the water. Adequate and efficient water flow through the filters is necessary for both the water quality and beneficial bacteria to stay in tip-top shape.
Luckily, this is an easy fix!
There’s all kinds of water conditioners, additives, and buffers on the market today that are specifically made to raise pH… for normal fish tanks, however. Since jellyfish are 96% water, they are a bit more sensitive to the chemical makeup of water than normal saltwater fish. So, adding in a bunch of chemical powders and liquids, especially into a small desktop jellyfish aquarium with less than 10 gallons of volume, isn’t always the best idea and can cause more harm than good! So, don’t do it!
Instead, we recommend the following tips to help keep your pH optimal:
Adding a bubbler is an easy and worry-free fix to raise pH. Bubblers (also known as aerators) constantly introduce oxygen to the water via bubbles. Most aerators include a valve or dial to alter the rate of bubbles giving you more control, which is even better.
It’s best to place the bubbler in the filter compartment, away from the pump, and as far down to the bottom of the tank as possible. This way, the bubbles are not being sucked into the pump and have a longer path to reach the surface, releasing a bit more oxygen into the water.
Note: You do not need an air stone, if one is included. These will only create smaller, erratic bubbles that have a higher chance of getting sucked up by the pump and into the jellyfish area – which you don’t want!
Always make sure your new saltwater has a pH of 8.0-8.2. This will help raise the overall pH of your aquarium and keep it up through weekly water changes.
We experienced this problem when working with the 6 gallon Cubic Orbit 20 jellyfish aquarium, as you can see in the video below that we put together some time ago.
Technically called “eversion,” it’s defined as the process of turning inside-out. In jellyfish, eversion is when the outer perimeter of the bell has flipped up and over the top of the bell, creating a saucer or cup-like body shape. The oral arms of the jellyfish also hang down and are not tucked up under the bell, as per a healthy jellyfish.
[Note: “eversion” is when the bell is flipped inward; “inversion” is when the bell is flipped outward. “Inversion” is commonly used instead to describe this process in jellyfish.]
Here are things that can cause jellyfish bell eversion:
Malnutrition leads to thin and weak jellyfish that are prone to flip
Flow rate is too high causing the jellyfish to spin like socks in a dryer
This prevents jellyfish from belling or swimming naturally, which means they also are not eating properly, ultimately leading to malnutrition
Flow rate is too low and the jellyfish are unable to bell properly due to the lack of “support” they get from the water movement
Belling problems always lead to eating problems—if they can’t bell properly, they can’t eat well, causing malnutrition (again) and creating thin, everted jellyfish
Physical damage that occurs when a jellyfish becomes stuck to the bottom or side of the tank for over an hour, damaging their bell
Luckily, these are all fixable issues!
Happy and healthy jellyfish should have rounded bells
Here’s how you can prevent eversion from happening:
Feed only nutritious, neutrally-buoyant foods on a daily basis to maintain proper cell growth and function
Adjust the flow rate just enough to keep the jellies off the bottom of the tank, but not so much that they are being propelled around the tank.
When trying to find the perfect flow, adjust your flow control valves and wait 20 mins between each adjustment to watch for a difference
Want to see an example of what proper flow looks like? Check out a few of our jellyfish aquarium videos on YouTube.
Maintain the proper flow rate and the jellies will not have the opportunity to get stuck for long periods of time
Read more about the physical differences between HAPPY (healthy) and SAD (unhealthy) moon jellyfish on our Jellyfish Troubleshooting page.
Let me start by saying this video and post were inspired by a real customer of ours, and the tank pictured is his real system. He was doing everything right to cycle his tank before he ordered his jellies, but for some reason the bacteria just weren’t doing what they were supposed to and his tank’s ammonia levels wouldn’t go down.
As we can see in the video, his tank was not quite level on its stand, and that was forcing the water to trickle unevenly over one side of the drip tray and bypass the other side. While that might not sound like such a big deal, it’s actually a recipe for disaster.
When your tank is leaning to one side, most of the water will obviously tend to flow that way, which means that all of your system water is flowing through only a very small part of your filter media. So not only will that water not be filtered properly, but the bacteria on the dry side of the filter media won’t be able to survive well enough to cycle your system and keep it healthy. Beyond that, keeping your tank on uneven surfaces can create uneven flow from the spray bars, cause a full sump to overflow and create troublesome air bubbles.
So what happens if you notice your tank isn’t quite level? Don’t panic! Just do what this customer did: wedge something underneath the low side of your system and adjust it until the drip tray gets proper flow! A simple fix like this can be the difference between a healthy system and toxic water, so keep an eye out!
Okay, it might not be that dramatic, but the amount of flow in your tank does have a huge impact on the health of your jellies.
Jellies are considered planktonic, which means they cannot swim freely against a current and therefore rely on some sort of flow to stay afloat. However, this doesn’t mean they need to be propelled through your system at mach 3. When you make your jellies race each other, nobody wins!
When the valves in the behind your EON jellyfish tank are fully open, like the one on the left side of the picture above, the your jellies will move so fast that they won’t be able to catch their food efficiently, nor will they be able to hold onto it if they do capture some. It’s almost like they’re getting motion sickness on the tilt-a-whirl at a carnival… forever. Understandably, they won’t react well to starvation and will stop belling and start shrinking until they die.
Instead, keep your valves at about 50% flow like the picture on the right. This gives them enough circulation to stay off the bottom of the tank while still giving them enough freedom to bell around and hold down their lunch.
Just remember: if the flow is too high, jellies die, moderate flow, good to go!
Now that your EON Jellyfish System is completely cycled, it’s ready for jellyfish! Watch Part 3 in our EON Instructional Video Series to learn about optimal water quality parameters for moon jellyfish and how to properly acclimate your new jellyfish once they’ve arrived at your doorstep.
Part 3: Acclimating Your New Jellyfish Opening sequence.
“It’s the moment you’ve been waiting for! Your tank is cycled and you’ve placed your very first order for jellyfish! Now wait one business day for delivery…”
“In the meantime, why don’t you double check to be sure your system water is suitable for new friends?”
“Your pH checks out.”
“Oh no, looks like your salinity is a little too high. You’ll need to bring it down by adding reverse osmosis or distilled water.”
“You can add freshwater to two places in your tank: the main viewing area or the sump.”
“NEVER add freshwater into your filter box.”
“This can kill all of the tiny bacteria you’ve worked so hard to grow!”
“Excellent, it looks like your tank is ready for jellies.”
“Well what are you waiting for? Let’s get them into their new home!”
“Don’t forget to take a look in the bag first to make sure they arrived safely.”
“Cut the bag below the metal bracket, then pull the tab to release the rubber band—No, no, no! Didn’t you read the sticker on the box?”
“You have to acclimate them first.”
“Take out a little water and slowly place the bag in your tank to float for 15 minutes to acclimate them to the water temperature.”
“Gently transfer your jellies with a ladle into a small cup full of water from the bag.”
“Carefully perform small water changes in the cup every 20 minutes for one hour to acclimate them to your tank’s water chemistry.”
“Now your jellies are ready to be released into your tank. Just look at those little guys go.”
Despite what some conspiracy theorists might shout at you, tap water is generally safe to drink for humans. For jellyfish, on the other hand, it might as well be poison.
Tap water contains small amounts of metals and minerals that you and I can hardly notice when we drink from the sink, but even in small concentrations, these elements can seriously disrupt a small jelly’s bodily functions and cause them to shrivel and stop belling. This is why we insist that whenever you add saltwater to your tank, whether you’re filling it for the first time or performing a routine water change, you ALWAYS mix the salt with either reverse osmosis (RO)water or distilled water, and NEVER use water from the tap, no matter how nice your filter pitcher might be.
Same goes for bringing your salinity down with freshwater: ONLY use RO or distilled when adding fresh water to your system.
*** Side note: bottled water is not always distilled water. Your jellies don’t drink Dasani! Jugs of distilled water are available at most grocery stores, but beware as there will be various types of water. Be sure it is labeled only as “Distilled Water” and not “Spring Water,” “Purified Water,” “Mineral Water,” “Alkaline Water,” or anything else. ***
Additionally, if your system maintenance requires filters to be rinsed periodically, it is best to do so with old saltwater taken from your system during a water change, rather than just running it under the sink. Your tank’s beneficial bacteria don’t care much for tap water either, and you certainly don’t want to make them unhappy.
The same rule applies with your algae scrubbers and any other items you might rinse and stick back in your tank. ALWAYS give them a quick dunk in some old salt water or some RO/distilled water and allow them to air dry before you place them back in your system. Your jellies will thank you!
If you’re looking into getting new pets, it’s always important to consider how long they’ll be with you, especially if you’re going to make the effort to set up a specific living space for them.
In our many years of experience, we’ve found that in small home aquariums, your pet moon jellies will typically live for about one year after their strobilation, or their ‘birth’, from the polyps.
Now that doesn’t mean they will necessarily live a full year in your tank. The distinction here is that we aren’t sending you a set of one-day-old jellies. It takes around 2 months for us to raise them to the 1-inch ‘small’ size, so by the time they get to your tank, they’ll have another 10 months to go. If you get the 2-inch medium size, it’ll probably be closer to 9 months, and so on.
But that’s only an average!
If you keep your jellies happy and fed with a stable water system, healthy bacteria, and constant water chemistry, they could last even longer. It all comes down to how well you maintain your system. And since you’re reading this blog, you’re well on your way to being a true jellyfish master– the sky’s the limit!
Introducing our EON Instructional Video Series – a new and improved video series to show you how to set up, maintain, and care for jellies in your new EON Jellyfish System from start to finish.
We made this series last year as a better way to actually show new and prospective EON owners what it takes to get one up and running with moon jellyfish (and how simple it is to do so!). We’ll be posting each video from the five-part series every week.
Below you’ll find the video and a follow-along script.
Part 1: Your EON & You Opening sequence.
“So, the day has finally come, your very own Sunset Marine Labs EON jellyfish tank has arrived at your door! Now what are you going to do?”
“Well, take it out!”
“But wait, do you have a proper surface in mind?”
“Well, is that surface level?”
“Can it hold more than 85 lbs.?”
“Excellent! Your EON jellyfish system should also be situated away from direct sunlight and nearby an available power source!”
“NOW would you like to see what’s inside?”
“In addition to your EON jellyfish tank, you’ll find:
shelves for the filter box,
power supply and instructions for your tank lights,
carbon filters, and
“Now, let’s add your premixed salt water, plug in the pump and put it all together!”
“First, place a shelf at the bottom of your filter box and add in the bio balls in an even layer…”
“…Then add a shelf…”
***please note: the micron pad is no longer included with EONs***
“…And place the three carbon bags on top, adjusting them so they completely fill the space for optimum filtration…”
“…Then add the thick mechanical filter pad…”
“…And place the drip tray flush to the inside just below the drain.”