Thursday, August 28, 2014

Water Quality in Jellyfish Tanks

What kind of tests should you be doing on your jellyfish tank and what levels are safe?

Jellyfish are interesting creatures in that they often appear okay with less than perfect water quality. They don't show many obvious signs and the jellies aren't talking. So what should you be testing for?

A good, basic and inexpensive test kit. 

Here is a list of the most important (In my opinion) factors to monitor in your jellyfish tank,

Ammonia- Ammonia is toxic to most invertebrates at low levels. Jellyfish have a knack for surviving in fairly high levels of ammonia that would easily kill other aquarium life. That being said, they might be surviving but certainly aren't thriving. Ammonia can burn at their tentacles and cause them to stop eating. High levels of ammonia also seem to be a factor in how long jellyfish live. It's best to keep ammonia as low as possible, as it affects their health in the long run.

Causes: Over feeding is the biggest cause. Dry or preserved foods are big ammonia creators. Having a good cycled aquarium with plenty of helpful bacteria will reduce ammonia build up.


  • Complete more frequent water changes and ensure that your tank has enough bacteria in it. This can be accomplished by seeding your tank with water from an established system or by adding any of the readily available "bacteria in a bottle" cycling products.

Nitrates- Nitrates are far less toxic than ammonia, but they accumulate over time. They are a product of ammonia being broke down. Nitrates tend to harm jellyfish in similar ways that ammonia does. High levels can slowly harm the jellyfish and cause an overall shorter life. Another side effect of high nitrates are increased bacterial and algal growth. Bacteria can feed on nitrates. Having a tank with really high nitrates can cause increased bacterial infections in jellyfish.

Causes: Nitrates tend to build up in aquariums over time. They accumulate due to a lack of frequent water changes or not enough to meet your systems production of them.


  • Water changes are the quickest way to lower nitrates. It's far better to stay on top of your water changes to begin with rather than doing massive water changes later. Jellyfish become used to high levels of nitrates and the sudden and rapid change can actually harm them more. 
  • There are a number of chemical filtration medias available to remove nitrates. Some work and others are just hype. They may be worth a try to lower your maintenance. Bio reactors are also a new form of nitrate removal. The employ the concept of growing bacteria on bio-plastics so they will remove the nitrates for you. 

pH- pH is another sneaky problem in jellyfish tanks. It slowly changes over time and suddenly your pH is way off. pH tends to be an issue when it becomes too low. This becomes an issue as the water leans towards acidic. The jellies can be burned and tend to have trouble consuming food.

Causes: Rotting food or dry and preserved foods tend to lower the pH. A lack of water changes will also result in lowered pH as various elements in the water are depleted.


  • Rapid changes in pH can be very dangerous to jellyfish. Use a buffer or basic (high pH) chemical to slowly bring up the pH over several days. Such chemicals include baking soda and sodium hydroxide. Note that sodium hydroxide will bring the pH up substantially as it is a very strong base.  A number of saltwater buffers are available at pet and fish stores, already mixed and ready to add. 

It is also a good idea to test for phosphates, nitrites and your alkalinity. These tests are important as well, but seem to have less of an effect on jellyfish. Phosphates can induce algal and bacteria growth as well.They are an issue with dry or preserved foods. Water changes will remedy them.

Remember: Nothing is better for your jellyfish than frequent and routine water changes!

Picture credits

1 comment:

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