Water For Discus

Discus arc not really difficult to keep ... as long as you do what they want! What discus want is: excellent water quality, free of toxins like chlorine, ammonia, nitrite, phosphate, etc.; correct water chemistry, especially pH and water hardness; and proper temperatures, between 82° and 86°F. Excellent water quality is provided by your filtration system (three-parts) and water changing system (one-part). Water chemistry should be periodically tested and determinations made for adjustments. The water should be soft, between 3 and 15°dH, and the pH should be between 5.0 and 6.5. This is where most discus keepers have trouble. Discus would prefer not to compromise on these values. To believe that you can acclimate discus to harder water, to higher pH levels, or to lower temperatures is folly. The discus may live, may even breed, in such conditions but they would be living and breeding under stress. In fishes, as in humans, stress shortens their lives and makes them more susceptible to diseases. Strive for the ideal rather than trying to cheat the system.

WATER CHEMISTRY

You can probably walk into any pet shop and find out what the general water conditions are in your area. That would be fine if you were tiying to decide whether to keep guppies or angelfish in your community aquarium, but it will not do for discus. You will need to test your own water as it comes from the tap and continue to perform periodic tests to ensure that your aquarium water is up to par and within the proper range for a number of values.

Testing the Water

You should initially test your water for chloramines and chlorine, pH, and alkalinity. Once the levels of pH and alkalinity in your raw water have been established, you can decide how you want to handle the situation. Some raw water is just about perfect for discus with little or no modification. Some water needs extensive conditioning before the first fish can be introduced. Once you know these values, you may even decide you want to keep another kind of fish! After the initial battery of water chemistry tests, you should continue to test it for the above, certainly after the first few water changes, and add a few more tests to the list: nitrites and nitrates, phosphates, and in the planted tank, iron and CO2. Simple, isn't it? Test kits have become very user-friendly in recent years. All these tests can be researched in a good chemistry book and the reagents assembled through chemistry supply outlets; however, the test kits and probes available for the aquarium hobby are generally inexpensive and easy to use.

Toxins in Ihe Water Supply

The water company can be your friend or your foe. Chlorine and/ or ehloramines are routinely added to the water in many parts of the world. A simple color test kit will determine the presence and concentration of either.

Removal of chlorine or ehloramines is part of the process known as conditioning your water. There is more than one way to skin a cat, and there are many ways to condition your tap water. Conditioning is the process of adjusting the chemistry of the water to bring it into line with the requirements of the fishes you are keeping.

• Chlorine is readily removed from tap water by activated carbon prefiltration, aging the water, or permitting contact of the water with the air through the use of a spray. Chlorine can also be removed by adding commercial chlorine removers. If you are conditioning your water with reverse osmosis or deionization, these processes remove virtually all toxins (and a lot of necessary elements as well, which must be replaced), but more about reverse osmosis and deionization later.

Chloramines are combinations of chlorine and ammonia, and some water companies need to use them for purification of the water supply. Chlorine is not good for fishes and chloramines are worse. If your test reveals the presence of chloramines, be sure to use a water conditioner that is chloramine-specific. Aeration will not remove chloramines.

Water Hardness and Alkalinity

It may be that your water hardness and alkalinity are perfect for discus but unfortunately this is not always the case. It is far easier to adjust hardness and alkalinity upwards when keeping hard-water fishes,

Test kits that enable the hobbyist to monitor various factors affecting the quality of aquarium water are available at your local pet shop. Photo courtesy of Wardley.

but lowering these values is by no means impossible. It simply involves another step in the water conditioning process.

Total hardness is the sum combination of the carbonate and noncarbonate hardness of your water. Total hardness is measured as DH, or ppm (parts per million). One DH is equivalent to 17.9 ppm. How total hardness is expressed depends upon the author and his or her orientation. 1 prefer °DH simply because as a discus keeper. I like to see smaller numbers when I am measuring water hardness! If I were keeping African cichlids I might prefer to measure my water's hardness in ppm. Total hardness is usually not a big issue in keeping discus; carbonate or temporary hardness is a far more important factor in the breeding of discus.

This refers to the levels of carbonates of calcium and magnesium. It is measured in °KH or rng/L CaCO, or parts per million. One milligram per liter (mg/U is the equivalent of one part per million.

Soft water is 3 D! 1 and 0 to 50 mg/LCaC04; medium soft water is 3 to 6 dH and 50 to 100 mg/L CaCO,; slightly hard water is 6 to 12 DH and 100 to 200 mg/L CaCO ,; moderately hard water is 12 to 18 °DH and 200 to 300 mg/ L CaCO.,; hard water is over 18 • °DH and over 300 mg/L CaCOr The values for general hardness and alkalinity given above do not always match each other. It is entirely possible to have a higher reading of general hardness and a lower reading of alkalinity. The lower reading for alkalinity is the more desirable for discus water. Discus will do quite well in slightly to moderately hard water. In fact, many breeders routinely keep their fish in these values to ensure proper development of the young, but for development of the eggs, soft to moderately soft water is critical. Therefore, it is not necessary to drastically adjust the general hardness or alkalinity when you first start to keep discus unless the values are very high.

Reducing Water Hardness

It is best to test the pH and alkalinity of your water before making any investments in reverse osmosis or cleionization equipment. As long as the general hardness and alkalinity are in the ranges mentioned above, you should have no trouble. Driftwood and peat will both contribute to softening of the water. You may find that your slightly to moderately hard water will respond very nicely to the introduction of a piece of driftwood and a bag of peat in your filter!

Beyond this, or if you are at the stage where you are seriously considering breeding your discus, you can look into reverse osmosis (R/O) or deionization (DI) pretreatment of your water. Both of these methods remove all traces of water hardness and a very high percentage of the impurities in the water through the extremely fine straining action in the R/O and specific resins in the Dl. Water that has been handled in this fashion is stripped of necessary trace elements and must be reconstituted before use in the aquarium. Reconstituting salts are available commerc ially. Some authorities recommend mixing the water with 5% tap water, but it your tap water contains toxins, this is not the best method by any means.

Household water softeners used in many homes are entirely unsuitable lor preparing water for discus. The resins in these units exchange hardness ions lor sodium ions and additional sodium is contraindicated in keeping discus.

About pH

Discus are very particular about pH. Keep your pH below 7 and above 5.5. The ideal pH for discus is 6. At pH levels above 7, discus are stressed. Below 5.5, the pH is inclined to plunge rapidly, so I find 6 to be comfortable for both the fish and the fish keeper.

Alkalinity and pH are closely related. Hard water naturally tends to be alkaline. Soft water naturally tends to be acidic. This is because of the buffering capacity. Buffering capacity represents the presence of alkalinity (carbonate hardness) and the ability of the water to maintain a high pH. It is a chemical balancing act. Just enough carbonate hardness and the pH remains at the desired level, too much carbonate hardness and the pi I will remain high, too little carbonate hardness and the pH will crash. Maintain your carbonate hardness at around 10° or 15°dl i and you should have no problems with pH. Cheek your pH with every water change until you are able to get a feel for how your water behaves. If you notice that the pH drops quickly, you must replace some carbonate. If your pll resists change to lower values, you must remove carbonate.

There are many methods of lowering your pH, most with some form of phosphoric acid, from drops to powders, but one of the gentlest and safest methods is through the use of peat moss. Because the peat adsorbs carbonates and acidifies the water, you should be able to maintain desirable pH and carbonate levels through the use of peat alone.

FILTRATION

Filtration is essential. Filtration is the life support system of the aquarium. Without filtration, your tish would soon die from the toxicity of their own wastes.

The Nitrogen Cycle

In the aquarium, beneficial bacteria—known as nitrobacteria—colonize the biological filter media and every surface of the tank. Nitrosomonas sp. is the nitrobacteria that consumes the toxic ammonia that is produced by decomposition of fish waste and other organic matter. The ammonia is reduced to nitrite. The nitrite is consumed by Nitrobacler sp. and reduced to nitrate, the least toxic end-product of nitrification. This process is called the nitrogen cycle and is the backbone of biological filtration. The nitrate is removed from the aquarium by your partial water changes (or in some cases by specific resins).

Mechanical Filtration

We should start with the mechanical filtration. Sometimes this is called prefiltration. The main goal here is to remove large floating particles of uneaten food, fish waste, and plant waste. There are many ways to accomplish this: sponges, pads, floss; practically any inert mesh-type material that will capture the dirt. Simple filter floss is very inexpensive and effective. Depending upon the style of filter you choose, the prefiller media is situated where the water first enters the filter. It may be that you will be using a small sponge filter on the intake tube of your power or canister filter. Some filters have special chambers for prefiltration media. Even the old-fashioned box filter with a layer of gravel and some filter floss will perform effective mechanical filtration. These fine materials trap the dirt as the water passes through them. Mechanical filters must be changed or cleaned weekly. Most people do not realize that this is necessary! Mechanical filters capture the gross particulates, solid waste that must be broken down to liquid • form before they can be converted by the nitrifying bacteria. It is far more practical to simply remove the solid waste than to wait for it to liquefy and then expect the biological filter to deal with its toxins. This is an error that very often leads to an overtaxed filtration system. So whichever met hod of mechanical filtration you choose, keep it clean! This is one area where you don't have to worry about preserving your bacterial bed. Just wash, rinse, or replace that mechanical filter media as often as possible.

Biological Filtration

Mechanical filtration is meant to take particles out of the water, nothing more. Usually mechanical filtration is confused with biological filtration because the same media is sometimes incorrectly used for both types of filtration. Biological filtration is the bacterial conversion of nitrogenous compounds that was described above in the nitrogen cycle. Where you want to clean your mechanical filter vigorously and often, the biological filter performs best when it can be left strictly to its own devices with a constant flow of particle-free, oxygenated water through the media.

There are many types of biological filters. The canister filter, which has been the mainstay of the advanced hobbyist, the trickle filter, which made its greatest impact in the saltwater hobby, the simple box filter, which is used with tremendous success by experienced fish keepers reluctant to give up on a filter that has been keeping fishes alive and well for the past fifty-odd years, the newcomer on the block, the fluidized bed bio-filter, and many more. Some tanks are maintained for years with nothing more than a simple sponge filter and air pump. The sponge filter is gently squeezed in a bucket of tank water onee a week and the resident nitrobacteria do a fine job of converting the ammonia and nitrite to nitrate. Regular siphoning of uneaten food and fish waste goes a long way to helping you keep a healthy tank with a very simple filtration set up.

As many different types of biological filters as there are, there are more types of media. Some examples of biological filter media include plastic hair curlers, "bio beads," gravel, sand, sintered glass, ceramic noodles, and so on. Biological filtration is critical to the health of your fishes. Whichever media you employ to harbor your nitrifying bacteria, remember that you want to keep the bacteria safe from harm. It lakes about six weeks for the nitrobacteria to establish themselves in the filter. During this critical period the ammonia and nitrite will reach high, maybe toxic levels. Keep your fish load very low in the new aquarium and be very careful not to overfeed. It is suggested that the tank be run with one or two very small and inexpensive fishes during this period. The water may cloud up for a period — the new tank syndrome. This is normal and will clear up presently. Once your filter bacteria have become established, the water will clear up spontaneously.

To maintain a healthy bacterial colony in the biological part of your filtration system, treat the media with gentle care. When cleaning the media, use only tank water. Do not use hot water or fresh tap water. A gentle rinse with tank water should be all you need to do if you have set up the system properly. The goal is to maintain the bacteria as undisturbed as possible on the media.

If your tank is without power for any length of time, it is entirely possible that your biological filter will crash. This happens when the bacteria are without oxygen for a period of time. This time period varies depending upon a number of

A ftuidized-bed biological canister filter. This one delivers over 20 times the biological filtering capacity of the same volume-rated trickle filter. Photo courtesy Merlin Red Sea Fish pHarm.

factors, but should you find that the filter has been off for a day, smells foul, and the fishes are gasping for air at the surface, do not simply turn the filter back on! The filter has become toxic and must be thoroughly cleaned and the media replaced before it can be used on the aquarium again.

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