Why Do We Water Test?
As it is impossible to confirm a fish is definitely happy by looking at it we test the water to make sure the conditions are coinciding with the fishes requirements. The water chemistry the fish is in is arguably the most important thing to get right when keeping fish. Species of fish can widely vary in their requirements so it is important to find out what water chemistry your fish require and know how to measure the parameters and what these readings translate to.
The first 4 key things we list to test for these we are going to classify as ‘seriouAn I parameters’ meaning that to test for these on a regular basis is absolutely critical to ensure you have a healthy tank. I am not by any means saying that the others are useless or unimportant, but if you are not testing for at least these 4 key things you are playing Russian roulette with your fish tank on the one hand you may never test and never have an issue but on the other hand you may have a filter crash and finding all your fish belly up is the first you know about it.
Water Parameters
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NH3 – Ammonia
Ammonia is possibly the number 1 killer of fish within aquariums, Ammonia is a toxin created in your water by fish waste, dead or decaying fish or overfeeding. Your filter within the aquarium houses beneficial bacteria that converts Ammonia (NH3) into Nitrite (NO2), If Ammonia is found to be present in the tank immediate action is required (water change, increase surface agitation & use an Ammonia detoxifier). Ammonia is highly toxic and is dangerous to fish at as little as 0.25ppm. The required reading for this parameter that you would hope to see on all freshwater aquariums is 0ppm. I recommend testing for Ammonia on a weekly basis and take care not to over clean your filters, over stock your tank, over feed your fish, add too many fish too quickly or wash your filters in anything other than aquarium water to prevent ammonia becoming present. A clear indication of Ammonia being present in an aquarium is lethargic fish, lingering at the surface & gasping for breath.
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NO2 – Nitrite
Nitrite is the next stage in the Nitrogen cycle (occurs in every established aquarium) it is another highly toxic chemical to find within your water column. Beneficial bacteria will convert Ammonia into a slightly less toxic chemical (Nitrite), the bacteria housed within your filter will then convert Nitrite into an even less toxic chemical called Nitrate. The causes of Nitrite is usually the same as the causes of Ammonia and the action we take when Nitrite is present is exactly the same. Nitrite is toxic at 0.5ppm and above. The ideal reading for this parameter is also 0ppm I advise taking the same precautions as you would with ammonia to prevent Nitrite spikes.
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NO3 – Nitrate
The end product of Nitrogen cycle (Ammonia>>Nitrite>>Nitrate). Nitrate being present in the aquarium is usually no cause for concern & completely expected, an increase in Nitrate levels with 0 ammonia and 0 nitrite reading also shows your tank is ‘cycled’ meaning the beneficial bacteria in your aquarium is processing toxins caused by fish waste correctly. Nitrate is however still a toxic chemical different fish have varying levels of Nitrate that they can cope with safely. For most species 40ppm or lower is acceptable however some fish may be at risk at anything above 5ppm, I advise checking what Nitrate level is acceptable for the fish you keep. Nitrate is removed by water changing and also feeds aquarium plants. In addition to testing the aquarium for Nitrate levels I also suggest testing your tap water (if you use tap water to fill your aquarium) as many areas particularly in the U.K have high Nitrate levels in tap water. Nitrate should be kept as low as possible for any sick or injured fish as it is still toxic and can affect the healing process. If you find your Nitrate is dangerously high then you either need to increase the volume or regularity of water changes or the replacement water you are using is also highly contaminated with Nitrate, a test will lead you to the answers. Nitrate is also acidic so dangerously high levels can begin to lower Kh and in turn eventually pH. In summary keeping Nitrate present, yet low is best for your fish.
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pH – Potential Hydrogen
pH is a measure of how acidic/basic water is. It is measure of a range between 0 and 14 with 7 being neutral, less than 7 being acidic and above 7 being basic. pH is a measure of the relative amount of free hydrogen and hydroxyl ions in the water. Water with more free hydrogen is acidic and water with more free hydroxyl ions is basic. A stable pH is incredibly important and keeping a fish outside their tolerable pH range can lead to disastrous consequences. I advise testing the pH in your tank often (preferably weekly) and in your source water, there are many things that can alter pH in an aquarium so be sure to check nothing in your tank is making an unwanted change. After researching the pH level your If your pH needs to be lowered or increased there are ways of doing so but changes should happen gradually as a fast change in pH can send fish into shock and cause fatalities.
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GH – General Hardness
This measure tells us all of the minerals dissolved in our water. The GH measure covers the hardness as an overall as opposed to just the carbonate hardness. Different species have different GH requirements so I would recommend checking your GH. Many fish keepers overlook GH and focus primarily on pH and sometime KH but an unsuitable GH level can be dangerous. I recommend testing your KH once a month or if an issue arises within your tank.
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KH – Carbonate Hardness
Carbonate hardness measures the amount of calcium carbonate (CaCO3) that exists in the water. KH prevents your pH from swinging and keeps things stable. Calcium is the most abundant mineral within water and it is very important for fish. If you want to change your pH you will first need to reduce your KH in order to do so. Again research your fishes requirements when it comes to KH. I recommend testing your KH once a month or if an issue arises within your tank.
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PO4 – Phosphate
Phosphates are present in almost every aquarium and although don’t cause any problem to fish directly they can feed algae, causing algae blooms which can deplete oxygen and indirectly hurt your fish. High phosphate levels are usually caused by poor maintenance within the aquarium so to keep on top of phosphates keep the aquarium clean. Phosphates can also be found in source water so it is recommended to test your source water as well as your tank for phosphates. The ideal phosphate level for most aquariums is 0.05ppm or less. I recommend testing the phosphate levels in your aquarium once a month of if an issues arises, particularly an algae bloom or green water.
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Fe – Iron
Iron is particularly important for planted tanks, in any planted tank it should always be present. It requires fairly high levels to affect fish health and can help algae flourish at very low levels. It is more likely to be present if your water comes from a well. I would advise that for planted tank keepers that are dosing with fertiliser, this test is required fairly regularly for those of you with no plants simply test your aquarium and source water on occasion or if you have algae blooms forming.
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Mg – Magnesium
Most aquariums don’t need magnesium. If your tank features only fish then you don’t need to worry about this trace element. However planted tanks may require magnesium to thrive, magnesium fertilisers are readily available to increase this trace element if your tank requires it.
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SiO2 – Silicates
Silicates can be found in source water and often found in aquariums using a sandy substrate being particularly high in the ever popular play sand that’s about £3 a bag in Argos. Silicates is a chemical that can leech out and assist with brown algae in the aquarium. Levels should be kept below 0.5ppm. Again this isn’t something you should need to regularly test for unless you are experiencing brown algae or concerned about this parameter. If your silicates are above 0.5ppm do not panic this is not harmful to your fish.
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Cu – Copper
Copper is present in most water to some degree however high levels can be toxic to fish, invertebrates and plants. Testing for copper is rarely needed but when using tap water it would be advised to test the copper level when you first set up the tank. One tip to help keep the copper level low is to run your tap water for a few seconds before filling the tank so any water that has been sitting in your copper pipes is flushed out. Dangerous copper levels for some fish is above 0.10mg per litre however copper is dangerous for shrimps, algae and bacteria lower than this. Copper is used in many medications to kill off parasites. If you find your copper level dangerously high you can buy products to remove copper from the water column such as poly-filter. I advise testing copper when you first setup an aquarium and then only if you are concerned you may have high copper within the tank.
Summary
I hope this gives you a good understanding of some of the most important water parameters to monitor within a freshwater aquarium. It is good practice to test all of your water parameters extremely thoroughly once a year or if you have a cause for concern. The serious water parameters should be tested weekly. The chemistry of the water literally will tell you what is going on within your aquarium, therefore if you notice a problem in your fish tank the first step you should usually take is to test your water, this is only a very basic guide I would recommend looking into water parameters further if you are unsure.