If you have an aquarium, dissolved oxygen (DO) is among the most important factors when measuring the quality of your water. Maintaining the right DO levels is also essential if you want your fish and aquatic organisms to survive and thrive. When oxygen reaches surface water, it dissolves because of the aeration from the wind.
It’s also possible for oxygen to be introduced into your aquarium water as a result of plant photosynthesis. If you’ve placed any plants in your aquarium, they will produce a certain amount of dissolved oxygen.
If DO levels drop too low, your fish might not survive. Keep in mind that cool water holds more oxygen. Several other factors can impact the aquarium supply dissolved oxygen, which include everything from salinity to overcrowding issues. In this guide, you’ll discover why dissolved oxygen matters and how you can measure it.
What Is Dissolved Oxygen and How Does It Affect Aquatic Life?
Dissolved oxygen is the total amount of oxygen that’s in the water. A water body can receive oxygen from aquatic plants as well as the atmosphere. When water is moving fast in a stream, it will dissolve more oxygen when compared to a lake or pond. In a still body of water, less oxygen is dissolved because of the lack of aeration.
Every aquatic animal requires dissolved oxygen to breathe. When oxygen levels are low, hypoxia will occur. If oxygen is absent in the water, this issue is referred to as anoxia. Hypoxia or anoxia can occur if the water contains too many organic materials. For example, let’s say that a body of water consists of numerous algal blooms. These blooms will be discomposed by the microorganisms in the water.
Dissolved oxygen is consumed throughout the decomposition process. When oxygen levels begin to deplete, the lowermost portion of the water column is affected first. In this situation, the organisms that live in the sediments will be impacted before the remaining fish notice the lack of oxygen.
Keep in mind that DO levels can also fluctuate periodically based on the time of the year as well as the daily ecology. When DO levels decrease, sensitive animals might move to other waters. However, these factors don’t impact aquariums.
When fish move through an aquarium, water flows through their mouths and passes the gills, which are located just behind the head. At this point, dissolved oxygen will be absorbed, which also results in carbon dioxide being released into the water. Gills contain thousands of blood vessels, which make it easier for fish to extract a considerable amount of oxygen from the water.
If the oxygen levels in your aquarium drop too low, the easiest way to fix this issue is by increasing movement in the water. When water moves faster, more oxygen will dissolve, which will also release carbon dioxide. You can increase the movement of aquarium water with an air pump or by manually stirring it.
If you’re keeping fish in an aquarium, it’s crucial that you maintain adequate DO levels. If DO levels drop too low, your fish will be unable to survive. Keep in mind that extremely high levels of dissolved oxygen can also kill fish and invertebrates.
Factors Affecting Oxygen Levels in Aquarium Water
From the temperature of the water to atmospheric pressure, numerous factors can affect oxygen levels in aquarium water. While it shouldn’t be too difficult to maintain DO levels, you’ll need to monitor these factors to ensure there aren’t any rapid drops or spikes.
- Water Temperature: When you’re trying to maintain the perfect environmental conditions in your aquarium, keep in mind that the temperature of the water impacts the amount of dissolved oxygen your fish have access to. Warm water holds considerably less oxygen. When the temperature of water rises, the solubility of oxygen decreases.
- Salinity: The salinity of water refers to the concentration of salt. Saltwater doesn’t contain as much oxygen as freshwater. Keeping your water clean and free of salts should help you maintain optimal DO levels.
- Atmospheric Pressure: DO levels are also impacted by the altitude and atmospheric pressure. At high altitudes, water will have lower dissolved oxygen levels. When the aquarium is closer to the ground, it shouldn’t be that challenging for you to keep DO levels from dropping too low.
- Overstocking and Overfeeding: If you add too many fish to your aquarium, you’ll effectively reduce the amount of swimming room that’s available to each fish.
In this scenario, fish will receive less oxygen and produce much more waste. Overstocking or overfeeding can lead to oxygen depletion, which means that your fish likely wouldn’t survive. A few additional factors you should be on the lookout for include the following:
- Low water movement that leads to a lack of aeration
- Poor tank maintenance that increases phosphate and ammonia levels
- Using specific medicines and chemicals
- A low-lighting environment
The Role of Plants in Oxygenation
Live plants in your aquarium contribute to the production of oxygen via the photosynthesis process. Photosynthesis occurs when light energy is converted directly into chemical energy. During this process, glucose molecules are made from carbon dioxide and water. Oxygen is also released as the main byproduct. The plants will receive the glucose molecules, which provide fixed-organic-carbon and energy.
Plants require light to perform the photosynthesis process. Solar energy is effectively harvested and converted into chemical energy. The various types of organisms that perform photosynthesis include plants, some bacteria, and algae. If your aquarium doesn’t receive enough light, the fish and plants within will continue to consume oxygen and produce carbon dioxide. However, no oxygen will be produced.
When you’re trying to maintain the perfect DO levels, there are some night vs. day differences that you should be aware of. For example, oxygen levels are typically at their lowest in the early hours of the morning. During the night, no photosynthesis occurs. However, fish must still breathe via respiration, which will reduce DO levels. In most cases, DO will be at its highest just before the evening hours.
How to Measure Dissolved Oxygen in Your Aquarium
The total amount of oxygen you need in your aquarium depends on the number of fish and plants that are stocked in the water. The species of fish also determines how much oxygen you need. Your aquarium should contain at least 5 mg/L of dissolved oxygen. Keep in mind that the ideal DO levels can vary based on the fish. If you have marine or saltwater fish in your aquarium, DO levels should range from 6.4-7.0 ppm. Freshwater fish require DO levels of 8.3 ppm.
There are a couple of methods you can use to measure the amount of dissolved oxygen in your aquarium. The simplest method involves using a DO test kit, which doesn’t cost much money and should give you decent readings. To use a test kit, follow the directions below:
- Obtain a sample of the water in your fish tank
- Place a few drops of the solution into the water
- Compare the chart from the kit with the color of the water
- Use the chart to determine the DO level, which you should write down
While these kits give you fast readings, they aren’t fully reliable, which can be a problem when you’re trying to maintain precise DO levels in your aquarium. Your best option is to use a dissolved oxygen meter aquarium.
These meters are highly accurate and should provide you with the exact level of dissolved oxygen in your fish tank. While there are several types of dissolved oxygen meters you can obtain for your aquarium, they use similar technology. You can obtain DO readings by adhering to the following directions:
- Plug the DO meter in before attaching the probe
- Place the tip of the probe into the aquarium water
- Wait for a few minutes to ensure the reading on the meter stabilizes
- Record the result that’s shown on the meter
It’s highly recommended that you regularly monitor the DO levels in your aquarium water. After you introduce a new fish to the water or perform chemical treatments, you should obtain the current DO levels to ensure there aren’t any issues you need to address.
Symptoms of Low Dissolved Oxygen in Fish Tanks
You can’t determine the amount of oxygen in a fish tank by simply looking at the water. There are, however, numerous signs that indicate your plants and fish aren’t receiving the amount of oxygen they need to survive. For example, your fish will begin to behave strangely.
Once O2 levels drop, the fish will likely swim slower to ensure that they won’t use as much oxygen. If you notice slow movement among your fish, you’ll likely need to take steps to increase the DO levels. For example, tangs are saltwater fish that are commonly placed in aquariums. These fish swim fast, which means that a sudden decrease in movement is a sign of low DO levels.
As touched upon previously, exceedingly low O2 levels can cause your aquarium to become hypoxic. When this occurs, your fish will display labored breathing. When fish are having difficulty breathing, their gills move rapidly in an attempt to quickly absorb O2. If the dissolved oxygen levels continue to drop, your fish may gasp for air by coming up to the surface of the water. They’ll also appear visibly distressed.
If only a small number of the fish in your tank are gasping at the surface, you should still address this issue. The fish that aren’t trying to obtain more oxygen will eventually suffer from the depletion of DO.
While each species of fish can have different DO tolerance levels, they regularly display stress when the DO level is less than 4 ppm. If the amount of dissolved oxygen in your aquarium reaches below 2 ppm, your fish will likely die from suffocation.
Keep in mind that labyrinth fish naturally gasp at the surface, which isn’t a sign that DO levels are too low. Catfish and gouramis often swim directly to the surface to take a gulp of air with their labyrinth organ. This process occurs quickly, which means that these fish should still spend most of the time below the surface of the water. If your labyrinth fish are often at the surface, you need to replenish the DO levels.
If you identify any of these issues, you must measure the level of dissolved oxygen in your aquarium water with a DO meter. As mentioned before, this type of meter is easy to use and should provide you with a precise reading in minutes. When you take measurements, consider the ideal dissolved oxygen levels for saltwater and freshwater fish.
Quick Ways to Increase Oxygen in Your Aquarium
Once you measure the DO levels in your aquarium water and detect that they are too low, there are several methods you can use to quickly increase the amount of oxygen in the water. First, consider pouring water into the aquarium from a height. This process will effectively aerate the water and increase the amount of oxygen. You don’t need to pour much water into the aquarium for this technique to have an effect.
You can also change the water. To do so, remove around 40%-50% of the water that’s currently in your tank. You’ll be able to pass a considerable amount of oxygenated water into the aquarium, which should replenish DO levels.
Consider increasing movement by stirring the water manually. This directly boosts aeration in the tank, which will increase oxygen levels. An effective method for increasing surface agitation across the water is to add ice cubes. If the DO levels are low because of higher temperatures, adding ice cubes should cool the water down. Make sure any ice cubes you place in the water are sealed in an airtight bag. Ice cubes contain contaminants that could cause fluctuations in other water quality parameters.
If you have a small fan, place it near the top of your aquarium to properly cool the water. The fan should also create ripples along the surface that increase water movement and oxygenate the surface. If you don’t use a fan or perform water changes regularly, make sure you use a temperature sensor to monitor any sizable fluctuations.
Occasionally, the power goes out. Whether an ice storm rolls through or heavy winds impact your area, a power outage can make it challenging to maintain proper DO levels. You can mitigate this issue by obtaining a battery-powered air pump. When the power goes out, hook up the air pump to ensure the water in your aquarium continues to move.
Long-Term Solutions for Maintaining Healthy Oxygen Levels
While the techniques mentioned above can be helpful when you need to quickly increase the level of dissolved oxygen in your aquarium, you shouldn’t rely on them. Instead, use long-term solutions that are designed to prevent low DO levels and provide a more permanent answer to this problem.
You can improve oxygenation in your aquarium by using a hang-on-back (HOB) filter. This type of aquarium filter is highly popular and easy to install. These devices have a small footprint and are designed to increase DO levels in aquariums. Once you install the filter, the water in your aquarium will pass through it, which should introduce aeration that’s evenly distributed throughout the tank.
You can also install a spray bar in your aquarium. If your tank is outfitted with a canister filter, you may already have a spray bar. Otherwise, you can buy this product online. Spray bars are designed to distribute filtered water through the entire aquarium, which will increase dissolved oxygen levels.
Consider using an air pump. This item is designed to send air directly into your fish tank with a powerful pump. It uses air stones to collect oxygen and eventually release it into the aquarium water. This is a cost-effective method for introducing oxygen to your water.
Best Practices for Preventing Oxygen Deficiency
To save time and money, it’s highly recommended that you focus on preventing oxygen deficiency in the first place. To begin, make sure you properly stock your aquarium and feed your fish. If your tank becomes overcrowded, the fish won’t have enough oxygen to breathe. If you notice that some of your fish have started gasping for oxygen, consider removing some and placing them in another aquarium.
You must also implement correct feeding practices. Most fish only need to be fed once or twice every day. Some people decide to not feed their fish on one or two days of the week, which gives them enough time to empty their digestive systems. If you have sedentary fish in your tank, their meals don’t need to be as large as active fish.
Along with overcrowding, you’ll need to avoid excess waste in your fish tank. This issue can eventually lead to low oxygen levels. If you don’t properly maintain your tank, you could experience clogged filters, excess waste, and algae overgrowth. You can resolve these problems by regularly cleaning your tank and performing ongoing maintenance.
If you’ve just purchased an aquarium, make sure you set it up properly. Low DO levels could be caused by installation issues. Once you install the tank, take measures to maintain movement in the water. Consider adding live plants to your aquarium. You should also use an aeration system that naturally moves the water.
When cleaning the tank, remove detritus from the surface. If you have mechanical filters in your aquarium, they should be cleaned regularly. When using biofilters, inspect them often to assess the effects of your medication or chemical treatments.
If you don’t have a dissolved oxygen meter, now is a good time to purchase one. This type of meter is a great investment for anyone who has an aquarium. Make sure you check oxygen levels in the morning and after you treat the water. If you spot fish gasping at the surface, test the water immediately.
Conclusion
Dissolved oxygen is among the most important aspects of aquarium water. The fish and plants you place in your aquarium need dissolved oxygen to survive. While plants will produce some dissolved oxygen, this process doesn’t occur during the day, which means that you may need to buy an aeration product or manually stir the water.
Monitor and maintain healthy oxygen levels to ensure the well-being of the aquatic life in your tank. With the right dissolved oxygen meter in hand, you’ll be able to accurately test the water and obtain precise DO readings.
Source link: https://sensorex.com/aquarium-supply-dissolved-oxygen/ by Joshua Samp at sensorex.com