A Guide to Nano Saltwater Aquariums

Stability:

Because nano saltwater aquariums are that much smaller, their fluctuations will be noticeably larger than that of a bigger tank.  Saltwater systems rely on stability.  This means that any changes you make need to be done slowly.  Anything from raising or lowering salinity, lighting levels or water changes, should all be done in small increments.

Water:

Tap water is not good enough for keeping saltwater fish in.  Using tap water will create all sorts of problems, not least algae blooms.  You will need RO water (see this article for more information).  You can make this at home using a filtration unit attached to your home’s water supply or you can buy it directly from your local fish shop (lfs).  When starting off, the latter may be a better idea until you’ve established that you want to carry on with a saltwater aquarium.  After that, you may want to invest in an RO unit.

Water testing:

You will need to have test kits in order to keep an eye on your nano aquarium’s parameters.  Test kits for phosphates, nitrates and alkalinity will be the main test kits you will need to start off with.  You can get your tank’s water tested at your local fish shop, buy a water test kit online (which you then have to send off in the post) but having your own test kits is much easier as you can retest the water’s parameters once you make any changes. 

Water movement:

Water movement is critical to all saltwater aquarium life.  Not only does it create flow that keep fish healthy through exercise but it circulates food and food particles, especially important when keeping coral and invertebrates.  Waste is moved about where it eventually finds it’s way into the filtration system.  You will not need anything as powerful as a gyre but a powerhead or two will do the trick. 

Evaporation:

Water lost through evaporation must be replaced with RO water and NOT SALT WATER.  As water is lost, the salt in the aquarium becomes more concentrated so you only need to replace the RO water that has evaporated.  You can make a small mark with a marker or a piece of tape where the tank’s water level should be.  Once it drops below that line, you can then add RO water to top it off.  

Filtration media:

Filtration media such as sponges and filter wool needs be cleaned regularly, more so than in larger aquariums.  If detritus is allowed to remain in the filter media, it will cause an increase in ammonia and nitrates which is toxic to fish, as well as encourage unwanted algae growth.

Feeding:

A big mistake that beginner nano saltwater aquarium owners make is to overfeed their fish.  Overfeeding only adds to the bioload of the tank and can end up causing unsightly, hard-to-get-rid-of algae.  It is recommended that you feed your fish small amounts twice a day.  Fish and invertebrates are constantly on the lookout for food which is why feeding smaller amounts twice a day is better than a large amount only once a day. You can read more about what to feed saltwater fish here. 

Substrate:

If using sand, one of the most popular is Caribsea.  Cured live rock (more on that here) should be added before sand however, as this creates a more stable structure.  If placed directly onto sand, the rocks can end up shifting due to the movement of sand underneath.  

Feeding coral:  

It should not be necessary to feed coral in such a small tank as the environment is small enough for food to pass them easily.  However, if you do, the same as feeding fish applies, do not overfeed.  

Tank maintenance:

Water changes should be done roughly once a week along with regular tank maintenance such as cleaning filters etc.  Water changes should be 10 – 20% of the tank’s volume.  This keeps your system stable with no increased levels of nitrates and reintroduces nutrients back into your aquarium.  

Carbon should be replaced monthly and filters cleaned regularly, depending on how dirty they get.