Useful Guide For Marine Fish Tank Water Treatment

Marine aquariums are a beautiful spectacle that entices many fishkeepers into the hobby. While taking on a saltwater fish tank can be a challenge, it can also be very rewarding. There are plenty of resources available that will assist you to make the set-up and care of your fish tank easy and achievable. We understand that sometimes a marine fish tank can seem more like a science lesson, so we are providing you with a guide to understanding how your water parameters are linked to common problems in a saltwater aquarium and the products to use to help. So if you are ready to start, or have just set-up, a marine fish tank, refer to our tables and water treatments below if you are experiencing any issues:

 Water Quality

Nitrite Nitrate pH Ammonia Phosphate  
  X     X Green Algae
  X     X Brown Algae
  X     X Red Algae
  X   X   Unpleasant Odour
X     X   Cloudy Water


Algae Control - We recommend adding AllPondSolutions Aquarium Rescue Algae Control to your marine tank to help control any red, brown and green algae growth. If your tank is growing any of these algae types, check your tank water’s nitrate and phosphate levels. Algae Control can assist with taking care of this type of algae, but in order to prevent future growth, carry out weekly and monthly cleaning routines.

If you test your water and the nitrate and phosphate tests reveal appropriate parameters, the algae could be the result of poor lighting and/or having your aquarium light on for too long. 

Bad Odour - Your fish are what produce ammonia and nitrate in your saltwater aquarium. The more fish you have, the more ammonia that will be produced; this is what leads to any foul smells. Make sure to change at least 10% of your fish tank water weekly to avoid the build-up of ammonia and nitrate. 

Cloudy Water - Ammonia also plays role in cloudy water. This is why we must emphasise the importance of doing weekly water changes!

Marine Fish

Nitrite Nitrate pH Ammonia Phosphate  
X     X   Lethargic Fish
X     X   Fish Gasping For Air
X X X X X Fish Developing Illnesses
      X   Fish Demonstrating Jumpy Behaviour
  X     X Not Adjusting To A Cycled Tank

Marine fish that do not seem to have any energy, or seem to be struggling to breathe, may be suffering due to excess ammonia and nitrite in their aquarium. Testing ammonia and nitrite with an at-home water test kit will help you to determine how much you need to reduce these levels. So what causes a spike in ammonia and nitrite? Overstocking your fish tank with livestock, excess fish food in the tank due to overfeeding, or something blocking the filter are a few of the most common reasons.  

Illness can develop in marine fish for a number of reasons (as you see in the table above). Poor water conditions in your aquarium cause your livestock a great deal of stress. Just like in humans, stress leads to a weakened immune system in your fish, which in turn, leaves them susceptible to illnesses. We have found that Easy Life Voogle is a safe way for your fish's immune system to develop resistance to a variety of illness that can be contracted by the negative effects of stress. If you are unaware of some of the most common fish diseases, read this blog post to find out more.  

If you notice your fish are jumpy or skittish, this is more than likely to do with ammonia levels being too high. Reduce ammonia in your marine fish tank by conducting a water change and add beneficial bacteria and an ion supplement like the Fluval Sea 3 Ions Supplement. 

If you add a new species of fish to your marine aquarium and they do not seem to be adjusting, this could be due to inappropriate phosphate and nitrate levels for the species. Each species of fish thrives in different water conditions. If fish are living in inappropriate conditions they will become ill, lose colour and even die. Before purchasing fish for your marine environment, please check their species specifications to make sure they will be alright in their new home. 

Marine Coral

Nitrite Nitrate pH Ammonia Calcium KH GH  
X X X X X X X Dying Coral
  X X   X X X Minimal/No Coral Growth
  X X X X X   Coral Not Opening

Arguably, the best part about investing in a marine aquarium is the ability to keep beautiful live rock and coral. Just like with your aquarium fish, marine coral can become unhealthy and die if not taken care of properly.  

If you have added new coral to your saltwater tank and they are not opening or growing, try adding Red Sea Reef Energy A & B Coral Growth. Due the multiple chemical reasons for little/no coral growth, this product will provide all of the necessary components to kick-start the growth of healthy live rock and coral.

If you can see that your coral are dying, it is likely that many aspects of your water levels are off. Live coral living in the wrong water conditions can undergo great stress and suffer. Red Sea Reef Foundation ABC Complete Pack contains most of the components (listed above in the table) that will aid in helping your coral survive. Another reason for coral death can be from poor water movement – referred to as dead spots. An easy fix to this problem is ensuring that you have a working wavemaker in your marine tank. 

Apart from these essential treatments, there are other additions that your marine aquarium will benefit from having. Iodine, found in seawater, helps with the cell functions used by coral that allow them to adapt to varying light conditions and is required for any shrimp in your aquarium molt and form new exoskeletons as they grow. Some other trace elements that should be tested for, and kept up with, are strontium and magnesium. We cannot stress enough how important it is to do your research on all organisms that will be living in your marine fish tank. This way you will have the best idea about which elements are vital to your aquarium.

As you can see, keeping a marine fish tank can be tricky. There are a lot of things that you need to keep track of in your tank, but you will get the hang of it! And, there are even products to assist you with correct chemical dosing, like a liquid dosing pump. We also stock a large range of water test kits that will measure all the water parameters you will need to know for your aquarium.