Tank Chemistry - Getting the Right Balance
Whether you have a freshwater or saltwater aquarium, it is vital that the chemical balance is maintained for the health of your fish. Poor water quality puts fish under stress and leaves them prone to pests and diseases. Fish are very sensitive to changes, so any change you make must be done with great care. When preparing water to add to your aquarium, you must ensure that the temperature is the same as that in your tank, and in a marine aquarium the salt level must be same, or incorporate only a small change. It is also advisable to aerate the water for 24 hours before you add it to the tank. This ensures the water is as clean and oxygenated as possible when you add it to your tank. The water you use is also vital to good water quality. You don't want to start out with bad chemicals in your tank that will affect your fish.
I'm going to lay out some of the principle points you need to know about your water quality, and ways of achieving a balance in your aquarium. The main elements you need to know about are:
Ph (Acidity & Alkalinity)
Ammonia
Salinity
Phosphates
Ph (Acidity & Alkalinity)
Ph is the measure of how acidic or alkaline your water is. Certain fishes prefer different Ph levels to others, so it's good to know what your fish prefer so that you can reach a balance. Sudden changes in Ph can be very harmful to your fish, so again, any changes must be gradual. In fact, it would be better to leave the Ph at an incorrect level than to suddenly change the Ph in your tank. The best way to regulate your Ph is to do regular tests. You can buy chemical test kits from your local aquatic store, and they usually do about 50 or so tests each.
The Ph scale runs from 0-14, 0 being the most extreme of acidity, 14 that of alkalinity, and 7 being neutral. Most fish prefer water with a Ph between 5.5 and 9.0, although there are some exceptions. The scale is logarithmic, each step up or down from neutral is ten times the previous one. This shows how a seemingly small alteration can have drastic consequences for your fish. Ph is affected by substances which are dissolved in it. Water-hardening salts tend to make the water alkaline, whilst soft water is slightly acidic. Decaying organic matter also increases the acidity of water.
Nitrites
Organic materials that contain nitrogen, such as fish waste, uneaten food and decomposing plants are broken down into different phases by specialized microorganisms. Total ammonia is degraded to nitrite, and finally nitrate. High nitrates indicate a problem with the biological filtration in the aquarium. As a guideline, nitrites should ideally measure between 0 - 0.3mg/l. You should not exceed 0.8, so regular weekly checks are required to ensure your nitrates are at a safe level. If your fish are exposed to nitrite levels of 1.6mg/l or greater for any length of time, it will be harmful to them.
A dirty filter is the main cause of nitrites in an aquarium. Also uneaten food and decaying leaves need to be removed regularly to maintain your water balance.
Ammonia
As mentioned above, ammonia is degraded to nitrites then finally nitrates. Ammonia is the most harmful nitrogen-containing material in your tank. If your Ph measures above 7 (neutral), toxic ammonia will increase. At levels under Ph7, non-toxic ammonium is present. Total ammonia in concentrations greater than 0.25mg/l is extremely harmful to your fish, especially if present for long periods.
If your ammonia levels are too high, there are certain methods which will help to reduce them. A partial water change and gravel clean will remove any decaying material or uneaten food, which will be affecting your chemical balance. Cleaning your filtration equipment in old aquarium water will prevent the loss of natural microorganisms that process waste material. Be sure that your oxygen levels are correct - the microorganisms need the oxygen to break down the nitrogen.
Nitrates
Nitrates can be successfully removed by anaerobic bacteria. If you wanted to do this, you would need to use a trickle system, where low flow rates and special filter medium keep oxygen levels to a minimum, to force the bacteria to find oxygen within the nitrates. This demonstrates the importance of letting your tank cycle before you add fish - your filtration has to settle in before it has to deal with waste. Patience here is vital - it is in your fishes ' best interest!
For a marine tank, you can use a protein skimmer to maintain your water's chemical balance. Protein skimmers use a process known as 'air stripping', where the proteins and organic bacteria stick to the air bubbles and the foam is removed along with the nitrogen matter. The most effective way of removing nitrates is through partial water changes - about 20% a week is a good guideline. But remember to follow the water preparation guidelines to make sure you aren't adding more nitrates to your tank or causing unnecessary stress to your fish. For more information on lowering nitrates, please read my article at:
Salinity
This is the measure of salt content in brackish and saltwater only. You can measure the salt content of your water with a hydrometer, which measures density. Aquarium water is usually made up of tap water and marine salts. These salts also contain trace elements that are beneficial to your livestock. You must never add domestic salt to an aquarium!
Reverse Osmosis Water (RO)
Reverse osmosis is a method of processing water. During filtration, all minerals are removed. However, all the oxygen is also used, so you must never add 'neat' or distilled water directly to your aquarium. It is important to aerate the water for 24 hours first. The drawback to the reverse osmosis unit is that it is very wasteful - it requires 10 gallons of tap water to create 1 gallon of RO water. If you have one of these units, try to use the waste water for something useful - you can use it to water plants if you're using a fertilizer at the same time, or washing dishes. Some aquatic shops process RO water and sell it per litre, which can be great if you don't want to invest in your own RO filter.
Phosphates
Phosphate levels should be monitored weekly. High phosphate levels result from overfeeding or poor water quality, and can lead to an increase in algal growth. In a marine aquarium, an increase of algae may cause certain invertebrates to overgrow. Removal of dead material, uneaten food and leaves will help to maintain your phosphate balance. Fish food contains phosphorous, which combines with oxygen and becomes phosphate when released into the water. Some tap water may contain high levels of phosphate, so it's important to test your water before you add it to your tank. The ideal range for phosphate is 0 - 1.0mg/l, in both saltwater and freshwater aquariums. Over 1.0mg/l is an indication of overfeeding or poor water quality.
