Maintaining Water Quality in an Aquarium

Water Tank

How do I stop the water from going cloudy/murky?

If everything is working properly, your water should not get hazy, muddy, or stinky. Overfeeding is by far the most prevalent cause of murky water. If your water is cloudy, look for ammonia. The presence of ammonia in the aquarium suggests that organic stuff (such as uneaten food) is degrading. Change the water, remove any surplus food (or dead fish/snails/decaying plant materials), and inspect the fish for symptoms of stress.

If no ammonia is present, the cloudiness might be produced by a variety of factors. There are a number of potential reasons why the water in your aquarium is cloudy; however, the most frequent causes of cloudy water can be narrowed down to a chemical imbalance in the water, algae and green water, bacterial bloom, and even debris from your gravel or plants.

The first time you set up your aquarium and add new plants as well as gravel or sand is often when you see the biggest algae growth. It is recommended that you wash these items before adding them to your aquarium or tank since it is likely that they have accumulated a lot of dust or have some loose particles on them that need to be washed away. It is very simple to accomplish this task; all that is required to clean plants is a light rinsing in some water. On the other hand, in order to clean gravel or sand properly, you must first thoroughly wash it in a container or bowl and then carefully filter the water through the material until it is clear. If items like pebbles or plants are the cause of your hazy water, the cloudiness will often only persist for a day or two until it settles down in the bottom of the tank, and it should not be hazardous to your fish in any way.

If the water in your tank has a hazy appearance that is grey or white in colour, this may be an indication that there is a bacterial bloom present. This is totally safe for your fish, and it is just the result of an imbalance in the bacteria that are present in the water and the waste and debris that are present in the tank as a result of the fish and any plants that you have. This is often something that will work itself out on its own as the tank ages, and it is typically just a problem with tanks that are quite new. If you want to get rid of it more quickly, a partial water change of around 20 percent should speed up the process. Additionally, eliminating waste and uneaten food from the tank (as well as avoiding overfeeding!) can help reduce the amount of waste that is mixing in the tank.

The presence of a chemical imbalance in the water is yet another potential explanation for the haze’s greyish hue. The presence of a greater number of minerals in the water or the addition of a significant amount of chemical additives are two possible explanations for this phenomenon. The use of a water conditioner, which helps reduce hazing by binding metal elements, may be helpful in this regard; periodically changing the water will also be helpful in this regard. However, you should examine the pH and hardness of the water that you are adding to your tank to see whether or not it might be the source of the problem. A typical contributor to chemical imbalances is the presence of gas bubbles in the water, which may be readily remedied by letting the water stand for some time so that it can reach room temperature at its own pace.

Even though there will be a dense cloud of green algae in the water, the fish will not be harmed in any way by the presence of algae, which is a typical issue in fish tanks. However, this does mean that you won’t be able to view your wonderful fish. It is possible to remedy this situation by ensuring that the tank is kept out of direct sunlight, limiting the amount of time that a light inside the tank is on to no more than 12 hours per day (as doing so may encourage the growth of algae), and changing the water on a regular basis in order to reduce the amount of nutrients that are providing fuel for the algae. It is common for this to be the underlying source of the algae, and if you adhere to these methods, you should be OK. However, in the short term, things like UV filtering or a diatom filter may be helpful. On the other hand, if the issue persists, you could have to relocate your tank or have a look at the filtration system and make adjustments to it.

Should I test my water and what do I test for?

Testing your water is strongly recommended, but not strictly necessary. The pH of the water is the most often used test. pH test kits are inexpensive and simple to use. The amount of hydrogen ion activity (also known as pH) in water indicates how acidic or alkaline it is. The pH scale ranges from 0 to 14, with 7 representing neutral, pH less than 7 indicating acidic water, and pH more than 7 indicating alkaline (also known as basic) water. Some fish originate from naturally alkaline waters, while others come from acidic environments, but virtually all thrive in water that is close to neutral. While a pH of 7 is considered “optimal,” most fish prefer a pH range of 6.5 to 7.5. It is pointless to attempt to keep a constant pH of 7.0 since pH changes based on water chemistry and the fish themselves.

As previously stated, fresh tap water is somewhat alkaline, while fish waste materials tend to make the water more acidic. This implies that the pH of the aquarium will steadily decrease over time. This is where the true value of a pH test kit resides. If you know your source water is neutral to slightly alkaline and your aquarium water has turned acidic (falling below 6.5), it is probable that additional waste materials have accumulated and it is time for a water change. By checking pH on a regular basis, you may pretty accurately determine whether or not you are doing adequate water changes. If you are, the pH of your aquarium should not go too low but should range from slightly acidic to neutral to slightly alkaline.

If the pH of your water remains low or declines rapidly, it might be because you are not changing enough water or your aquarium is getting overcrowded. If the pH of your water gradually rises, you most likely have marble or limestone in your gravel or other decorations. Some fish don’t mind the increased pH, while others don’t. It is preferable to identify and eliminate the cause of the issue.

Other waste products may also be tested directly, with kits available for evaluating ammonia, nitrite, and nitrate. These are often more costly than pH test kits, and may include many chemicals, but they provide a more thorough view of aquarium conditions. (For additional information on the function of these chemicals in water, see here.)

If you are experiencing unexpected fish deaths or hazy, stinky water, you should do an ammonia test. If you feed your fish too much, the uneaten food will decay and release ammonia. Ammonia may also be an issue if too many fish are introduced into a freshly set up aquarium (before filter bacteria can be developed), or if filtration bacteria have been killed off by excessively chlorinated water, a medicine, or a buildup of solid waste product. If everything is working smoothly, there should be no detectable ammonia. Checking the ammonia, particularly in a freshly set up aquarium, is a good idea to ensure the filtration is functioning and appropriate. If you discover that there is no ammonia at all times, you generally don’t need to keep testing. Keep an ammonia test kit on hand, though. If anything goes wrong, this is the first thing you should look for. If you discover a high amount of ammonia in your water, do a water change but do not clean your filter media unless it is clogged with debris that is causing the issue. In severe circumstances, an ammonia remover or a dosage of helpful microorganisms might be added.

The breakdown of ammonia produces nitrite, which is subsequently broken down to nitrate by filter bacteria. Again, if all goes properly, no nitrite will be detected. If your filtration isn’t functioning, you’ll normally notice ammonia first, but if no ammonia is present, nitrite might be the reason. Although less hazardous than ammonia, a nitrite may nevertheless cause sudden and inexplicable fish deaths. Treatment for nitrite is identical to that for ammonia: replace part of the water without disrupting the filter, and in extreme situations, add a helpful bacterium.

The ultimate waste product is a nitrate, which, although less hazardous than ammonia or nitrate, is nonetheless undesirable. Nitrate levels that are too high for too long are stressful for the fish, and nitrate also stimulates algal development. In most circumstances, a low pH indicates that nitrate levels are high, but when limestone and/or marble are present, the pH rises and cannot be used as a guide. Nitrate should be checked for directly in these circumstances. If you replace your water on a regular basis, your nitrate levels should remain much below 100 ppm. To reduce algae, you may wish to maintain the nitrate level even lower by doing bigger or more frequent water changes. If nitrate levels remain high or rise fast, your aquarium may be overcrowded.

Other items may be tested for in your water, although they are not usually essential. Other things to look out for include:

While oxygen is plainly necessary, it is difficult to test for. Any agitation or shaking of the water will raise the oxygen concentration, rendering the test worthless. Electronic probes are available, although they are somewhat pricey. If the water is persistently low in oxygen, the fish will normally dangle just under the surface, gasping. Change part of the water in this situation, and if an air pump is available, add an airstone or enhance airflow to the tank.

Water hardness in general is a measure of dissolved salts. Some fish originate from naturally soft waters (poor in dissolved salts), whereas others come from hard water (high in dissolved salts). The majority of fish you purchase will be adapted to the hardness of your local water source. If you are not using the same water as the shop where you purchase your fish, and particularly if you are using bore water, rainwater, or a combination of the two, measuring hardness is a good idea. In terms of pH and hardness, try to get a water mixture that most nearly reflects the water from which the fish came. Another time you may need to evaluate hardness is if you want to breed specific fish species, especially those that need soft water to breed (e.g. neon tetras), or if you want to use copper sulfate to cure snails or illness since this should not be used in extremely soft water.

Carbonate hardness is a measure of the concentration of dissolved carbonate salts. Carbonate salts contribute to pH determination. If you notice that the pH of your water is extremely steady, it is most likely being “buffered” by the carbonates present. Your water may even remain slightly alkaline. This is normally not a cause for concern; in fact, a steady pH is preferable. As a result, a certain amount of carbonate hardness is beneficial, and you may test it if you like, although it is typically sufficient to monitor pH. If you want to utilize CO2 fertilization on your plants, carbonate hardness should be tested since it is extremely desired to have a modest carbonate hardness to make this procedure most efficient and to maintain the pH consistent as CO2 might otherwise cause pH to decline.

CO2 (Carbon Dioxide) (CO2). This should be investigated in areas where CO2 fertilizer is employed. A compromise must be struck between delivering adequate CO2 for the plants while not suffocating the fish. Testing for CO2 is frequently unnecessary if CO2 fertilization is not employed. CO2 will only be excessively high in this situation if there is overfeeding or other decomposing organic material in the tank. As a result, oxygen levels will be low, and the fish will display their suffering by gasping at the surface.

Phosphate is a waste product that encourages algal development. It is commonly formed from uneaten food. It is not dangerous to fish, but if you have algae issues, you may want to test for phosphate. If you’re feeding low-quality fish food, it might be adding a lot of phosphate to your water. You should also test your source water for phosphate.

Iron is a nutrient that is required for plant development. If your plants aren’t growing well, you might consider testing for iron deficiency. When fertilizing plants, it is a good idea to check iron levels to ensure that you are delivering enough and not excessive fertilizer. Iron is also found in certain water sources and, at high concentrations, may be harmful.

Calcium is a mineral that corals need; measuring calcium can ensure that you are supplying enough of this important ingredient in reef aquariums.

Copper is utilized in many drugs and, in excessive concentrations, may be hazardous to certain species. If you retain sensitive species and wish to use a copper-based medicine, make sure the copper content does not exceed the recommended dose.

How do I change the pH or water chemistry?

Many compounds are available to change the pH and other characteristics of water chemistry, but they should be handled with care. As previously said, if you are utilizing the same water source as where you purchased your fish, there is typically no need to modify the pH or other parameters of your water (usually the local tap water). The fish you acquire will be used to this environment, and introducing them to a sudden change in water conditions is one of the fastest ways to stress or even kill them.

The pH is the most prevalent feature of water quality that you may be tempted to adjust. You may discover that the pH of your freshly installed aquarium is too high and want to lower it. However, keep in mind that your fish’s waste products make the water more acidic. If you start with water that has a lower pH, it will turn acidic much faster. Furthermore, chemically decreasing the pH of your water might ruin its natural buffering function and make the pH exceedingly unstable. Alternatively, you may discover that the pH of your water has fallen over time. In this scenario, a water change is preferable to employing chemical treatments to elevate the pH. Replacing part of the water raises the pH and dilutes other waste products.

If you haven’t changed the water in your tank in a long time and the pH is really low, one water change may not be enough to bring it back up to the desired level. You should nonetheless avoid the temptation to use pH-raising agents. If your fish have been at a low pH for a while, they will not like the abrupt return to a much higher pH. Other waste products will also be present, but at higher proportions, than is ideal. Perform a week-long series of water changes, removing little more than half the water each time, until the pH is close to neutral.

However, there may be situations when you need to change the pH for other reasons. Because of your location, you may be obliged to utilize bore water or rainwater, or you may choose to maintain or produce species with tighter water chemical needs. It is considerably better to alter the water chemistry before introducing any fish. The golden rule of altering water chemistry is to never drastically alter the chemistry of the water in which the fish are swimming. If you currently have fish in an aquarium and wish to modify the water chemistry, take some water, adjust the water outside of the tank, and then replace it.

If you do not have access to the same water as the location where you purchased your fish, you should strive to match their water chemistry as nearly as possible. If you only have bore water, it is usually harder and more alkaline than regular tap water, but rainwater is likely to be softer and more acidic. If you have both, you could discover that combining them produces water of acceptable quality. If you only have one or the other, you may need to modify the pH and hardness.

Unless you are maintaining highly delicate species or attempting to breed them, it is seldom essential to modify water chemistry to suit certain fish. You may wish to soften and acidify the water for particular tetra species, or you may want firmer, more alkaline water for brackish water species. If you are modifying your water to accommodate these species, be careful to only mix them with other species that like similar circumstances.


1) Using pH down: Take a bucket of the water you wish to alter from the tank (or directly from your water source) and mix in one level teaspoon of pH down. Mix well and set aside for 30 minutes. Check the pH. If you have fish in the aquarium and wish to reduce the pH somewhat, the pH of the water in the bucket should be less than the final desired pH (but not too much, otherwise the fish will be shocked!). If required, lower the pH and wait another half hour. When the proper pH is obtained, gently refill the aquarium with water. If you’re altering the pH of your supply water to match that of a store, add pH down in the same way until you achieve an appropriate pH. (generally still slightly alkaline is best). Allow the water to stand overnight before testing again the following morning. If the pH has increased again (due to natural buffers in the water), putting additional pH down will most likely have no effect. It may be better to get rainwater, distilled water, or reverse osmosis water to blend with your source water.

It is important to note that commercial pH-lowering solutions include sodium biphosphate, which may contribute to algae growth. This approach has no effect on water hardness.

2) Filtering water via peat or blackwater extracts: While filtering water through peat is a traditional way of decreasing pH and hardness, blackwater extracts provide a comparable effect and are preferred merely because they are simpler to use. These will not result in significant pH reductions and may be applied straight to the tank. The only major downside of this procedure is that if used in big quantities, the tannins from the extract (or the peat) would give the water a noticeable yellow hue. Even again, it is just a drawback if you detest the effect, since many fish like the extra tannins (it may even boost spawning!).

3) Using distilled or reverse osmosis water: This is often the best option, and it may be combined with other ways if needed. The primary downside is the expense of RO water and water purifiers (especially as the resins they contain have only a limited life span). They are, nevertheless, important if you wish to retain and produce very delicate species. Rainwater may also be utilized, but only if you are certain it is clean.


1) Using pH up: Use this in the same way as you would pH down. Although the chemical used to elevate pH (sodium bicarbonate) does not boost pH as much as pH-lowering agents do, it is still prudent to exercise care.

2) Adding marble chips: This is the ideal approach if you want to maintain species that need hard, alkaline water. When you add marble chips to your gravel or filter, they will gradually dissolve and elevate the pH. They will not boost it over the pH that these fish enjoy, but keep in mind that not all fish prefer a high pH.

3) Add water with a greater pH or hardness (or do a water change).

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