Differences between a freshwater and saltwater aquarium

First of all let us help you understand better by answering the questions most frequently asked. Oftentimes, we get asked questions regarding the differences and difficulty level of keeping marine fishes in comparison to freshwater fishes. The marine fish keeping hobby is no doubt more difficult to maintain as compared to the freshwater fish keeping hobby. But before we come to the conclusion of exactly how difficult it is to maintain, let us highlight a few key differences.

Difference 1 - Livestocks

Freshwater fish are more hardy as compared to saltwater fishes. The reason is attributed to the natural environment. The natural freshwater environment experiences cyclical changes which occur oftenly. These environmental changes include flooding, drying thus impacting the chemical composition of the water. Moreover the water chemistry in the water swings frequently. As compared to the natural saltwater environment, the ocean. Natural freshwater environments are considered to be inconsistent and dynamic. 

In the ocean, the condition of the water does not change much. For example the salinity and pH rarely swings by a significant amount enough to affect life in the ocean. Thus, the living conditions for saltwater fish are generally constant leading to the ocean’s stable water chemistry.

Their natural environments thus caused them to be where they are today. Freshwater fishes are able to survive in a variety of water conditions while saltwater fishes are only able to survive in a strict range of water conditions. 

In summary, freshwater fishes are much hardier in the aquarium hobby. Mistakes made which impact the water chemistry can often be corrected. However, with saltwater fishes, a small mistake can be lethal to the saltwater fishes due to their inability to adapt to sudden changes in water chemistry.

Difference 2 - Equipments

To get a basic understanding of the second difference, it is important to first understand what equipment is required for a freshwater aquarium as compared to in saltwater aquariums. The below is a summary table of the basic equipment used in the respectful aquariums.

At the base of every successful aquarium is a good filtration system. An effective system usually consists of water going through a 3 stage filter. Water firstly goes through mechanical filtration followed by biological filtration and then lastly through chemical filtration.

• Mechanical filtration uses sponges, filter socks, floss and pads to physically strain out debris from the water. 
• Biological filtration consists of porous effective biomedia which houses beneficial bacteria which consumes toxic ammonia and nitrogen compounds that comes from fish waste and uneaten fish food.
• Chemical filtration uses special resins or activated carbon that removes medication or impurities from the water. However, Once the chemical filtration becomes saturated with impurities, the media is no longer able to absorb pollutants from the water.

In a freshwater aquarium, the most popular and best filtration to use are your canister filters due to its efficiency in filtering waste and handling bioload. In the saltwater aquarium, the best filtration used are sump tanks due to the convenience and benefits it carries.

As for lighting, the most common colour temperature which a planted aquarium would require is 6500k. In a reef tank however, the most common colour temperature required is 11000k. The price of the LEDs used in a freshwater planted aquarium vs a saltwater reef tank can prove to be of significant difference indeed. The main reason as to why marine LED lighting costs more than freshwater LED lighting is due to the huge reduction in energy cost as they convert power into light more efficiently. Moreover, reliable LEDs which allow for successful healthy coral growth is a relatively new technology.

Freshwater aquariums, as the name suggests, do not require salt like a saltwater aquarium does. A wavemaker and protein skimmer is also not required in a freshwater aquarium. In a saltwater aquarium, a constant salinity level is extremely important as stability is key. A wavemaker is also important as it replicates the natural ocean environment and prevents any surface film from forming resulting in an inefficient gaseous exchange.

Lastly, the main difference in equipment is a protein skimmer. The protein skimmer is frequently seen running in marine aquariums but not in freshwater aquariums. Why? You might ask. The reason is due to freshwater not being as dense as saltwater. Dissolved organic material would simply not get separated like it would in a saltwater aquarium. Due to this, a protein skimmer would lack the ability to form fine air bubbles that creates froth or scum to be pushed up to be collected in the overflow cups. Thus, a protein skimmer is simply not required in a freshwater tank but is extremely handy for a saltwater aquarium due to its efficiency in removing dissolved organic waste.

Difference 3 - Costs

The last major difference between freshwater aquariums and saltwater aquariums would be the costs. Freshwater aquariums are known to be significantly cheaper than saltwater aquariums but is there any truth to this?

From difference 2, it is broken down that saltwater aquariums do indeed require additional equipment to run successful aquariums. The cost of the additional equipment and marine livestocks is usually doubled as compared to the freshwater counterpart. Most freshwater fish purchased range from a dollar to 10 dollars. For saltwater fishes however, the cost is greatly dependent on the specific species and availability of the fish. The range for the saltwater fish hence, ranges anywhere from 3 dollars up to a hefty price of 3 digits.

In a nutshell, saltwater aquariums are not essentially more difficult to start as compared to the freshwater aquariums. However, needless to say there is simply more to understand and learn in the saltwater aquarium hobby. Maintenance wise, it is also more demanding in the saltwater aquarium aspect. Hence, it is important to note these major differences before deciding on your first or subsequent aquariums. Most importantly, the livestocks, equipments as well as the costs are the ones that ultimately aid in the decision making process.