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Caring For Your Fish & Water Parameters

Starting A New Tank

Unlike nature, an aquarium is a closed environment. All the wastes excreted from the fish, uneaten food, and decaying plants stay inside the tank.  The water may look clear, but don't be fooled. It's loaded with toxins.

Sounds awful, doesn't it? Fortunately bacteria that are capable of converting wastes to safer by-products begin growing in the tank as soon as fish are added.

Unfortunately there aren't enough bacteria to eliminate all the toxins immediately, so for a period of 5 weeks or so, your fish are at risk. When setting up a new tank, it is important that you understand the nitrogen cycle, in order to reduce this risk.

The Nitrogen Cycle

Initial Stage: The cycle begins when fish are introduced to the aquarium. Their feces, urine, as well as any uneaten food, are quickly broken down and ammonia is produced. Ammonia usually begins rising by the third day after introducing fish.


Second Stage: During this stage Nitrosomonas bacteria oxidize the ammonia, thus eliminating it. However, the by-product of ammonia oxidation is nitrite, which is also highly toxic to fish. Nitrites levels as low as low as 1 mg/l can be lethal to some fish. Nitrite usually begins rising by the end of the first week after introducing fish.


Third Stage: In the last stage of the cycle, Nitrobactor bacteria convert the nitrites into nitrates. Nitrates are not highly toxic to fish in low to moderate levels. Routine partial water changes will keep the nitrate levels within the safe range. Established tanks should be tested for nitrates every few months to ensure that levels are not becoming extremely high.


Adding New Fish

Step 1: Float the bag in the tank for 5 minutes to help the tank to acclimatise to the difference in the water temperature. This is especially important for less hardy fish, such as Angels.

Step 2: Open the bag and roll down the edges so that the bag is able to float on the surface. Put a mug of water from the tank into the bag to help with further acclimatisation.

Step 3: Wait 10 minutes and add another mug of water from the tank into the bag.

Step 4: 

Helping your fish get used to your aquarium is important if your fish are going to remain healthy through this critical period of transition. Fish don’t like surprises. They do not react well to rapid changes in temperature, handling or rapid movements. Always make sure you handle them gently and allow them sufficient time to get used to new surroundings.

Do not try to add too many fish to a tank too quickly, especially to a new tank. This will result in an extremely high level of ammonia and nitrite in your tank that may kill your fish.

Carefully remove the fish with your net and place them in the aquarium.


Water Changes

The regularity and amounts of water changes needed will vary greatly dependent on the size of your tank, the amount and size of the fish inhabiting it, and your feeding levels. A good basis to start with is to do a 10% water change each week. The more fish you have, the more waste there will be in the water, and the more often it will need to be cleaned.  Replace the water you take out with dechlorinated water at a similar temperature to the water in your tank.

Always use a gravel cleaner to do your water changes as it will keep your stones clean and help to prevent your pH from dropping.  It is also a convenient way to remove the water from your tank.

Important Tips

Always use the cold water tap in the kitchen for water changes as this is a fresh supply, bring it up to room temperature with a little water from the kettle. The hot water taps and bathroom taps shouldn’t be used as this water usually comes from a copper tank and copper is harmful to fish.

Never use detergents for cleaning your tank or ornaments, and do not refill tanks from buckets which have previously held detergents.

Algae pads are excellent for helping to clean away any dirt and algae from the tank and ornaments.


Understanding Water Parameters

Cause: Ammonia in the tank is converted to Nitrite by Nitrosomas bacteria, so excess Ammonia will lead to excess Nitrite. Nitrite should always be zero in an established aquarium. Exposure to Nitrite can lead to disease or death.

Effect: Nitrite exposure can cause Nitrite Poisoning, which leads to Brown Blood Disease. An increase in methemoglobin in the fish will have fish gasping for air at the top of the tank, acting listless, showing very fast gill movement, and can cause red/brown gills. The methemoglobin renders the blood unable to carry oxygen. Low level exposure to Nitrite over a period of time will weaken the fish's immune system and leave it more prone to secondary infection over time.

Treatment: A large water change, up to 50%, will provide immediate relief for the fish, and aquarium salt (preferably Chlorine salt) should be added according to package instructions. Increasing aeration of the water will improve survival rates. If your fish are suffering from Nitrite poisoning, the water should be tested daily until the Nitrite has reduced. Reducing feeding will help to prevent reccurent issues.

Prevention:The key to eliminating fish death is to avoid extreme spikes and prolonged elevation of nitrites. When starting a new tank, add only a couple of fish initially and do not add more until the tank is completely cycled. In an established tank, only add a couple of new fish at a time and avoid overstocking. Regular water tests will catch any problems early.

Cause: High levels of Nitrate can be caused by overstocking a tank with fish, overfeeding the fish, and not doing regular water changes. Often, high levels are caused by a combination of overfeeding and lack of regular water changes. It is normal to have a low level of Nitrates in tank water, under 50ppm is reasonably safe for hardy fish species.

Effect: Nitrate is relatively harmless at low quantities but exposure to high levels of Nitrate over a prolonged period of time leaves fish weakened. Additionally, if you take a fish from a low level of Nitrates e.g. a shop, and put it into a high level of Nitrate, it may not be able to cope and die. The fish that are in the tank already are used to the higher levels of Nitrate. 

Treatment: It can be difficult and a long process to get the Nitrate level down. For example, if your Nitrate level is 100ppm and you do a 50% water change, it will not bring your Nitrate level down to 50ppm. This is because the EU standard for drinking tap water is set to 50ppm so it can contain anything up to this level.

Prevention: Regular water changes will prevent a build up of Nitrates in your fish tank, as will keeping feeding levels low. A Nitrate sponge is an important part of the Juwel filtration system, and should be changed every 6-8 weeks to keep Nitrate levels down. This provides chemical filtration of Nitrates from the water. Plants use Nitrate as a fertiliser so planting your tank with live plants will also help.

Cause: High Ammonia levels in an aquarium are most often caused by overfeeding or overstocking of a tank, or a combination of both. Toxic levels of ammonia can also be a consequence of filter failure, whether this is due to the powerhead stopping or being clogged, toxins such as Chlorine killing bacteria in your filter, or algae blocking progression of water through the filter media.

Effect:Ammonia poisoning can happen suddenly, or over a period of days. Initially the fish may be seen gasping at the surface for air. The gills will begin to turn red or lilac in color, and may appear to be bleeding. The fish will begin to lose its appetite and become increasingly lethargic. In some cases fish may be observed lying at the bottom of the tank with clamped fins. As the damage from the ammonia poisoning continues, the tissues will be damaged as evidenced by red streaks or bloody patches that appear on the body and fins.

Treatment: If the ammonia level rises above 1 ppm as measured by a standard test kit, begin treatment immediately. A 50% water change will provide immediate relief. Several water changes within a short period of time may be required to lower the ammonia. If the fish are in severe distress, the use of a chemical to neutralize the ammonia is recommended. Feedings should be restricted so that additional waste is reduced. Ammonia becomes increasingly toxic as the pH rises above 7.0. At a level of 1 ppm, fish are under stress, even if they don't appear in acute distress. Levels even lower than that can be fatal if the fish are exposed continuously for several days. For that reason it is critical to continue daily testing and treatment until the ammonia drops to zero. When ammonia is elevated for a long period, it is not unusual to lose fish even after the ammonia levels start to drop.

Prevention:The key to avoiding fish death from ammonia poisoning is to avoid ammonia spikes. When starting a new tank, add only a couple of fish initially and do not add more until the tank is completely cycled. Even in a well established tank, only add a couple of new fish at a time and avoid overstocking. Feed small quantities and clean the tank weekly, taking care to remove any dead plants or other debris. If a fish appears to be ill, test for ammonia to rule out ammonia poisoning. If the filter stops working, test for ammonia twenty-four hours later to ensure that the bacterial colonies that eliminate wastes were not affected.

General Hardness (GH)GH, also known as Total Hardness, of water depends on which type of land areas the water has passed through. Varying levels of hardness are reached before it reaches its final destination, for example if it passes over rocky areas it will have a higher mineral content, and if it passes over marshy, forest areas it will normally create a soft water river or lake. When we turn on our taps the mains water will contain many minerals that it has absorbed on its way to us, mostly magnesium & calcium, with small traces of other metals such as iron and zinc. The concentration of these minerals determines the general hardness of our water.

Carbonate Hardness (KH)

With an aquarium, nitrates in the water will produce nitric acid, which in turn will reduce the pH if there isn’t enough buffering capacity to neutralize the effect. It is generally accepted that the KH should never drop below 4.5 or else this can cause major pH instability which is detrimental to the health of your fish. Regular water changes will reduce the nitrates so that less nitric acid is produced, therefore a more stable pH is reached which will prevent it from dropping over a period of time. As expected the higher the hardness of the water the better the buffering capability. To raise GH and KH levels in an aquarium, Coral Gravel should be added.

Potential Hydrogen (pH)

Neutral ph is 7.0, above is alkaline and below is acidic. Most readily available fish are tank bred rather than wild caught, and suit a ph of 7.0. pH is linked to both KH and GH. Keep in mind that pH is not static, it changes over time, in fact it even changes over the course of a single day. Typically it drops at night and rises during the daytime. The pH will change as new fish are added or removed, as water is added or changed, and as the biological processes change other parameters within the tank.Some fish are more sensitive than others to changes in pH, which can lead to lower immune systems and may kill weaker fish. Neon Tetra are typically very sensitive and can be shocked by changes in pH.

If the pH is too low, but the GH and KH are at acceptable levels, it is likely that the gravel in the tank is not being cleaned regularly enough. A gravel cleaner should be used at every water change.