Are Saltwater Aquariums Hard to Maintain? A Beginner’s Guide

Saltwater aquariums have a somewhat undeserved reputation for being extremely hard to maintain, and this has deterred many people who would otherwise really enjoy the hobby of saltwater fishkeeping from starting up a saltwater tank. 

Are saltwater aquariums hard to maintain? The answer is no, a saltwater aquarium is not hard to maintain, provided some basic concepts about marine ecosystems are understood and practiced by the person setting up and maintaining the tank. These concepts include:

  • Filtration
  • Circulation/current
  • Live rock and live substrate
  • Mixing sea water
  • Water testing and supplements
  • Saltwater maintenance tools and supplies
  • Live specimen compatibility

If a person who has never kept fish takes the time to learn about these different aquarium concepts as they apply to maintaining a confined ecosystem, they will find themselves able to set up and enjoy both saltwater and freshwater aquariums. Read on to find out how to set up a saltwater aquarium the easy way. 

Saltwater Aquariums: Not Hard, But Expensive

Maintaining a saltwater tank is not all that much harder than setting up a freshwater aquarium. If anything, people vastly underestimate how difficult it is to set up a freshwater tank properly. The major difference between freshwater and saltwater aquariums is having to mix in salt during every water change and perform water changes more diligently to maintain correct salt levels. 

While a freshwater aquarium can get away without getting a water change for a few weeks and be none the worse for wear, such a period of neglect can have much worse consequences in a marine ecosystem due to the different chemical sensitivities involved. 

Since these weekly water changes for a saltwater tank cannot be safely skipped without damaging water quality, and salt must be purchased and added for every water change, for large saltwater aquariums that can be a lot of marine salt, which can get expensive. 

Not only that, most of the equipment involved in saltwater tanks is generally more expensive than the same equipment used in freshwater tanks. This is partially because saltwater is corrosive and requires stronger materials but is also the result of saltwater aquariums being perceived as a luxury item. 

Here is a list of supplies necessary to start up a saltwater aquarium (before adding fish or other live specimens other than live rock):

  • Aquarium with hood 
  • Aquarium lighting
  • Powerhead
  • Skimmers and filtration equipment
  • Live rock 
  • Substrate
  • Heater (or chiller)
  • Sea salt mix
  • Hydrometer
  • Thermometer
  • Air pumps/air stones
  • Saltwater testing kit
  • Limewater, iodine, and other supplements
  • Buckets, siphons, and cleaning tools

All this equipment can range easily into hundreds of dollars. One of the constraints of saltwater aquariums is that by necessity, they must be bigger than many freshwater tanks, and the smallest nano reefs are not kept in tanks smaller than thirty gallons. 

Some people have kept nano reefs in even smaller tanks, but such tanks are not tolerant of environmental swings and are best reserved for experienced aquarists.  

As anyone who has kept an aquarium can attest to, thirty gallons is quite an investment in comparison to a smaller tank, both in terms of time and equipment costs. Saltwater tanks overall cost roughly twice as much as their freshwater counterparts to set up. But that doesn’t make them harder to maintain.  

Saltwater Filtration

Filtration in aquariums is a process in which beneficial bacteria clean ammonia, nitrites, and other toxins out of the water and render it safe for the fish and other animals that call it home. Filtration is also what is responsible for making sure the water remains crystal clear for optimal viewing conditions. 

Without filtration, tanks would quickly succumb to algae infestations, and the fish and other animals in them would die from their own waste ammonia. This ammonia is toxic to fish and can kill them even in very small amounts, making filtration a vital part of aquarium maintenance. 

The good news is that once a saltwater filtration system is properly established, the bacteria in it are self-sustaining as long as the water quality (and water levels) are kept up. 

Along with filtration, saltwater aquariums also utilize protein skimmers to help keep nitrates in the aquarium down. This is especially important for keeping live coral, an animal that is very susceptible to nitrate poisoning. 

Circulation and Current in the Saltwater Aquarium

Another important concept to understand with regards to setting up a saltwater aquarium is circulation. In addition to normal filtration equipment, saltwater aquariums require powerheads in order to generate an underwater current. 

Powerheads help to mimic the current found in saltwater habitats, and also benefit saltwater tanks in the following ways: 

  • Increases circulation and efficiency of the filtration system
  • Stimulates animal activity and delivers food to stationary animals such as coral
  • Deters the growth of algae (which tends to bloom in stagnant water)

When choosing a powerhead, it’s a good idea to choose a well-known and respected brand such as Marineland or AquaClear rather than an off-brand powerhead, as you’re more likely to get better technical support if you need it with a reputable company.

It pays to choose a powerhead that can be easily disassembled and reassembled, as you may have to clear an obstruction from the impeller at some point. You should also look for a powerhead with a guard over the intake to make sure that none of your tank’s occupants accidentally gets sucked up into the system. 

Live Rock and Live Substrate in Saltwater Aquariums

Before you get involved with any fish for your saltwater aquarium, you need to consider purchasing live rock and live substrate. Live rock is dead coral that contains live microscopic and miniature marine life on and within it. 

Buying live rock for your saltwater aquarium can help jumpstart your saltwater ecosystem, but before you add live rock to your tank, it should be cycled for several weeks with no live animals (just like with freshwater aquariums) to establish the nitrogen cycle and a beneficial bacteria colony for the filtration system. 

There are two major kinds of live rock used in saltwater aquariums:

  • Reef rock: This is live rock taken directly from a saltwater reef or which has broken off of a reef and is considered the superior choice for stabilizing a saltwater system.

  • Inshore rock: Inshore rock is coral that is taken from the interior of a reef and is more likely to house unexpected stowaways. These can range from harmless mussels and bristle worms to major hassles like aipasia anemones that can kill your fish.

  • Dead rock: Dead rock is completely dried former live rock that does not contain any living micro or macro-organisms. It is sometimes used as a foundation to lay down other kinds of live rock in a reef aquarium. 

Live rock has many different functions in the saltwater aquarium. It acts as the primary biological filter for the tank, helping to remove excess toxins in the water column, and also serves as a natural home for many of your tank’s denizens. 

Because many saltwater fish are still wild caught from the ocean, they can be more fragile and sensitive to habitat than freshwater species. This means that replicating their natural environment as closely as possible is vital to maintaining their health. 

Mixing Sea Water for a Saltwater Aquarium

There are two ways you can get saltwater to maintain a saltwater aquarium: premixed saltwater bought by the gallon, and a synthetic seawater mix that is mixed into freshwater to convert it to saltwater. 

You might be tempted to use premixed saltwater for your aquarium, and this can certainly take a lot of the difficulty out of trying to maintain it, but these gallons of premixed saltwater are much more expensive than mixing the water yourself. 

If you can afford to buy the saltwater premade, it does save a lot of work and money associated with saltwater maintenance. But using a synthetic seawater mix to mix your own saltwater, you can save a lot of the money associated with saltwater maintenance, and it’s really not that difficult. 

For a saltwater aquarium that only contains fish, you can get away with mixing tap water. However, if you want to have a reef aquarium, you’ve got to use a reverse osmosis system to generate reverse osmosis/deionized (RO/DI) water for your tank. 

To mix sea water for your aquarium initially, you’ll need the following supplies

  • Tank
  • Submersible water heater
  • Thermometer
  • Powerhead to maintain circulation
  • Hydrometer (to measure salinity)
  • Something to stir with

Note: It is important not to add live rock or live animals to a saltwater aquarium until the nitrogen cycle has been established to prevent fish and animal death. 

To mix up a batch of sea water for a water change on a saltwater aquarium, gather the supplies and then perform the following procedure:

  1. Add freshwater (either RO/DI water or tap water) to the aquarium. Be sure to leave a gap at the top of the water, as adding substrate, live rock, and other features into the aquarium will displace water.
  2. Add the thermometer to the aquarium and record the temperature of the water.
  3. Add the powerhead and heater to the aquarium. The aquarium should be set at the optimal temperature for the marine life you intend to be adding to the aquarium.
  4. Place the powerhead in such a way that it causes visible turbulence at the surface of the tank’s water. This will help with oxygen dispersion in the water column.
  5. Add the sea salt mixture to the water and stir to mix. The amount of salt mixture to add into the water will vary according to the instructions on the manufacturer’s label. You should add the sea salt in three parts, being sure each part is fully dissolved before adding the next.
  6. Check the salinity of the water with a hydrometer. You’re looking for a specific gravity between 1.020 and 1.024. If the level is lower than 1.020, add more salt incrementally until you reach at least 1.020, or if the level is higher than 1.024, add more water until the specific gravity is 1.024 or less. 
  7. Let the saltwater stand overnight and leave the powerhead running so it can continue to circulate the water and aerate the tank.
  8. After letting the saltwater solution sit overnight with the powerhead running, measure the salinity again and check the aquarium’s temperature.
  9. Be sure to let the aquarium fully cycle (over a period of several weeks) and test for a functioning nitrogen cycle before adding live rock, which should be added and established before adding live fish or marine invertebrates. 

Once an aquarium is established, water will need to be changed out each week at a volume of roughly 20% and should be topped off occasionally to account for evaporation. 

To prevent any shock to the fish, you should test the water temperature and salinity and make sure they are equivalent to the temperature and salinity in the tank. This will help you prevent any stress, illness, or shock-related death in your fish. 

Saltwater Water Testing and Supplements

While it may seem like it adds a lot to the maintenance schedule of a saltwater aquarium, doing water quality tests on your saltwater aquarium allows you to catch problems with chemical levels or water quality at an early stage before that problem becomes dangerous to the inhabitants of your tank. 

Water Testing

Saltwater testing kits are widely available both online and in pet supply shops and contain all of the necessary chemicals to test the levels in your aquarium. Like freshwater test kits, saltwater test kits test for the following water parameters:

  • pH: pH is the measure of how acidic or basic a solution is; ideal pH is determined by the type of specimens kept in the tank
  • Ammonia: Ammonia is an inorganic compound produced as a waste product of animals living in a saltwater aquarium; if not removed via the nitrogen cycle, it can quickly kill a tank’s inhabitants
  • Nitrite: Nitrite is the substance formed when beneficial bacteria convert ammonia; nitrite is still toxic to fish until it is further converted into nitrate by other kinds of bacteria
  • Nitrate: Nitrate is the least toxic compound of the byproducts produced by living organisms in a saltwater aquarium, but is still toxic to aquarium inhabitants in cumulative doses; nitrate should be removed from saltwater aquariums through weekly water changes and dilution

While there are other you can monitor for in an aquarium, monitoring these four parameters is the most important aspect of testing your aquarium’s water quality. 

Since a build-up of these toxic chemicals in aquarium water can kill the aquarium’s inhabitants quickly, it’s important to check these levels at least once a week to keep on top of things. 

The easiest way to simplify the weekly chore of testing water quality is twofold. It is easier to remember to test water quality if you do weekly water changes at the same time and batch the two chores together. This is also a good time to generally observe your tank and each of the animals in it to assess their health and behavior. 

Maintaining a saltwater aquarium can seem overwhelming, but it doesn’t have to be. If you dedicate an hour or so once a week to maintaining your aquarium, it will stay immaculate. Maintenance of a tank is much easier when you start with and keep up a good baseline. 

Saltwater Water Supplements

Along with sea salt mix, there are other supplements you can add to your saltwater tank to enrich the water and help encourage new growth in your live rock and corals. Seawater is one of the most nutrient and mineral dense solutions on Earth, and it can be difficult to recreate this diversity in captivity. Saltwater supplements help with this task.  

These nutrients are vital for marine life and become naturally depleted as their bodies use it up. The major minerals that need to be added back into a captive marine ecosystem include the following: 

  • Calcium: Calcium is an important element for the health of corals, clams, invertebrates, and some kinds of algae.
  • Strontium: Strontium is necessary for marine life to develop their skeletal systems.
  • Carbonate: Carbonate is used as a source of carbon for animals in saltwater aquariums, and also as a pH buffer in the aquarium’s water.
  • Magnesium: Like the other hard minerals listed, magnesium is used by marine life to formulate their skeletons and as a pH buffer. 

There are also minor trace minerals that are vital for the health of an enriched saltwater aquarium, and they include the following: 

  • Iodine/iodide
  • Iron
  • Molybdenum
  • General trace elements

Because aquarists can get these mineral supplements to add into sea water mix during water changes, they have come close to being able to being able to reproduce optimal seawater conditions found in the wild. 

Saltwater Maintenance Tools and Supplies

Along with the appropriate electrical equipment for filtration/skimming/circulation and the proper chemical ingredients to recreate seawater, you will also need some basic supplies and maintenance equipment in order to keep your saltwater aquarium up. 

Here are some of the basic maintenance tools you should acquire in order to keep up your saltwater aquarium: 

  • Cleaning brushes
  • Buckets for water changes
  • Gravel vacuum for cleaning substrate
  • Containers/trap
  • Tweezers/tongs/scissors for aquascaping
  • Nets for catching fish

Along with the equipment used in water changes and cleaning the aquarium, you should also keep water conditioner and dechlorinators on hand, as well as first aid supplies for your fish in case of breakouts of illness in your tank. 

It can also be advisable to keep backups of some of your equipment, such as backup air pumps and filters. This can be extremely useful to have in case your equipment suddenly malfunctions and you aren’t able to immediately go out and replace it.  

Live Specimen Compatibility in Saltwater Aquariums

When setting up a saltwater aquarium, it’s important to learn about each type of animal and plant you are keeping in your aquarium on an individual level to find out what their optimal environmental parameters are.

In the case of saltwater fish, many kinds of fish cannot be housed together without one type of fish trying to kill another, either out of predatory instinct or due to territoriality (many reef fish are highly territorial). 

Another thing to keep in mind is the compatibility between corals and fish. Many saltwater fish are not compatible with corals because they will eat the coral or strip it of life, and some inhabitants of reefs, such as anemones, are dangerous to smaller fish. 

The needs of the animals you keep and live specimen compatibility are important to make sure half of your aquarium’s inhabitants don’t try to eat or kill the other half, so be sure to confirm specimen compatibility before you purchase any live animals for your tank.  

Setting Up a Saltwater Aquarium

The initial steps of setting up a saltwater aquarium are not that much different than the steps involved in setting up a freshwater aquarium. You’ll want to choose the aquarium’s final location before filling it with water, as once it is filled, it will weigh several hundred pounds and will be impossible to move without draining it. 

And with saltwater aquariums, draining it to move it is not an easy feat, and could easily result in the loss of some of your fish. So it’s important that you choose the location of your tank wisely. 

After choosing a spot for your aquarium (with plenty of nearby electrical outlet support for aquarium-related gadgetry), you need to:

  • Place the aquarium and clean it to ensure there is no residual chemicals or dust from the manufacturing/storage process. You don’t want any traces of cleaner or other chemicals to end up in your tank.
  • Place a background on the aquarium and secure (if you’re using one). You can either use a solid-colored background or choose a marine-themed photo to add verisimilitude to your tank. A background also helps fish and other aquarium features show up better.
  • Place all filtration equipment and wire it (bundling the wires together can prevent them from water contact as well as make the setup more neat-looking in general). Make sure to leave enough room behind the aquarium to easily access equipment.
  • Install powerheads and protein skimmer. These pieces of equipment aren’t typically used in many freshwater aquariums, but in saltwater tanks, strong circulation to mimic oceanic waves and good efficient filtration are vital to protect water quality and prevent stress in your tropical fish and invertebrates. 
  • Install the aquarium heater. It should be noted that under no circumstances should your filtration equipment or heater be operated outside of the water. Running a submersible filter dry will burn up the motor in a hurry. Running a heater while dry will possibly cause it to burn out and crack or malfunction entirely.
  • Once the tank has been cycled, add live sand. This will temporarily cloud the water, but the sand should settle after a period of several hours.
  • Add decor, live corals, lighting, and other features to the aquarium. Make sure that you have everything where you want it and let the tank stabilize with live rock and corals in it for several days before adding fish.
  • Add live fish and invertebrates. It is recommended to add fish and invertebrates a few at a time, rather than all at once, in order to avoid disturbing the nitrogen cycle and bombarding it with too much ammonia all at once. 

Maintaining a Saltwater Aquarium After Setup

While setting up a saltwater aquarium can be daunting at first, once the aquarium is set up and stabilized, weekly maintenance is actually pretty easy. If you set the time aside each week to complete the following tasks, maintenance of your saltwater aquarium will be simple:

  • Weekly water changes. This is the single most important thing you can do with your aquarium to maintain its water quality and the health of your animals.
  • Weekly tank monitoring. Each week you should set some time aside to look at your aquarium and take notes of any problems you might have. Keeping a close eye on the tank allows you to catch problems quickly and solve them before they become serious issues.
  • Weekly water testing. In addition to testing levels of ammonia, nitrites, nitrates, and pH, weekly water testing should also include testing salinity. This can allow the aquarist to add more water if evaporation has caused salinity levels to increase.
  • Feeding. When feeding fish and invertebrates, it’s important to remember that less is more. Adding more food than your fish can eat can pollute the water and cause ammonia levels to spike as the food decays in the water column.

    After feeding, all uneaten food should be removed after a period of roughly fifteen minutes. Feeding should be done every day, preferably twice a day, to reduce the amount of food fed at a time. However, fish are hardy and can survive a period of several days without food if pressed. 

Saltwater Aquariums Are as Easy as Any Other Tank

Aquariums may be fairly low maintenance, but it only takes a little neglect for an ecosystem in a tank to spiral out of control. 

The aquarium depends on the aquarist to maintain every parameter, so this means that the person maintaining the aquarium needs to be dedicated to weekly water changes in order to reduce maintenance in other ways. 

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Adam Edwards
Hi, my name is Adam and I'm an aquarium enthusiast! I didn't discover the joys of being an 'aquarium fanatic' (as some of my friends call me!) until I was in my 20's. When I first started out I found it difficult to find all the information I needed so I started this website to compile all the useful information I can think of. Enjoy!