Aquarium Water


PH is the measure of acid or alkaline in your water. The proper pH is necessary for your fish to be healthy and stress free. Some species (most live bearers) require alkaline water, while others (egg layers) prefer water that is more acidic. Most however, will do well in water with a pH ranging between 6.8 to 7.0. This is best if yours is a community tank, housing a number of different species. If it is not within this range, you might need to make an adjustment.

When buying your new fish, ask what their pH requirements are.

The water in your aquarium can become more acidic when the tank is dirty, especially if there is uneaten food in the tank. Often, all that is required is a cleaning and a partial water change to raise the level to what’s more comfortable for your fish. If your tap water doesn’t raise the pH level enough, there is a product called “pH Up” that will easily remedy the problem.

Should your water be too alkaline, you’ll need to make it more acidic with a product called “pH Down”. (This product is an acid and care should be taken when using it, as it will cause burns to the skin.)

When adjusting the pH in your aquarium, you must do so over a period of a few days. This makes the change more gradual, minimizing the risk of too drastic a change, that can harm your fish.


Most freshwater fish prefer soft water with a hardness less than 8°dH.

Medium soft water would be between 8° to 16°dH; hard water is 16° to 25°dH; and finally extremely hard water is over 25°dH.

If you experience problems lowering the pH of your water, it is probably due to the dH or gH. Hard water contains excessive amounts of magnesium and calcium that tend to prevent your pH adjustments. You’ll need to remove these minerals to soften the water before you can lower the pH.

There are products available to alter the hardness of your water.

If you experience problems maintaining a less alkaline pH and your water is not hard, it may be due to your substrate (gravel). Some substrates contain lime which will increase the hardness of your aquarium water and in turn raise the pH level. Should you suspect this is a possibility, test the hardness of your tap water and compare it to the hardness of the water in your aquarium.


Ammonia is probably the most common hazard and killer of fish in aquariums. It is always present in the water, but should be at such low levels that it would be undetectable to your test kits. At higher levels the water will sometimes have a cloudy white appearance.

This toxin can build up in your tank’s water due to overcrowding (too many fish), uneaten food and excess waste products in the gravel bed or external filter. So much so that the bacteria in your gravel bed and filter systems can’t keep up with it. If it reaches such high levels, it must be lowered immediately as it is literally suffocating your fish.

To do this you must gravel clean your tank to remove all the ammonia causing debris as well as to replace 25%-50% of the toxic water with fresh, clean, dechlorinated water (see chloramines). There are Ammonia-removing products that you can buy to remove the remaining excess ammonia.


Nitrate is the end result of the nitrogen cycle and can accumulate in your aquarium to very high levels. While it is generally harmless to fish, it can be deadly to invertebrates, even at lower levels.

High levels of nitrate (combined with bright light) contribute greatly to the growth of algae causing it to “take over” your aquarium. Reduce nitrate levels and keep algae to a minimum by performing weekly, 20-30% water changes with fresh (de-chlorinated) water.


Ordinary household cleaners and chemicals are poisonous and deadly to your fish. Soap, aerosols, furniture polish, air freshener and spray paints etc, when used in or around your aquarium can kill your fish. Be sure that your aquarium is well covered when using any of these products near your tank, and avoid any contact with the water should your hands have traces of soaps or chemicals on them. A few precautionary measures will help to prevent any sudden, unexplainable deaths.

Chloramine may now be being added to your drinking water. If you use tap water for your aquarium, it could be killing your fish.

Chloramine may now be being added as a disinfectant to your drinking water.

Chloramine is deadly to both fresh and salt water fish, and like chlorine, must be removed from the water if to be used in an aquarium.

While chloramine is in fact a combination of chlorine and ammonia, it takes much longer (weeks) to dissipate from the water than if it were chlorine alone. Now the chlorine must be separated from the ammonia before it can be removed and requires either a water-conditioner or filter media specifically designed for its removal.

Some water treatment products do not remove chloramine. If you are currently using a tap water conditioner, check the bottle, it may be that it also removes chloramine or “breaks the chloramine bond”. If not, you might need to obtain one that does. If you find this is happening to your water supply it is usually the best idea to buy a water purifier.


A common misconception about aeration is that the bubbles actually add oxygen to the water. This is not true. The rising bubbles circulate the water causing carbon dioxide to rise towards the surface. Through surface agitation, a gas exchange takes place. While the carbon dioxide and other gases leave the water, the oxygen moves in. The greater the surface area of agitation where the gas exchange can take place, the better oxygenated your water will be. Therefore, a small air stone will only help to aerate the water very little, while a longer stone would do a much better job.

Note: The use of a powerhead is an excellent way to aerate your aquarium.

Watch your fish, should you notice labored breathing, breathing at the surface, or clamped fins, it is usually an indication that there is something wrong. Should any or all of these symptoms be displayed, test your water for ammonia and nitrite immediately. The only acceptible test result is “zero”.

If properly cared for, you shouldn’t have any problem keeping your tank free of these toxins and maintaining the required pH level. Regular water changes and not overfeeding your fish are your best defenses against poor water quality.

Please Note:

Under no circumstances should you add any salt water accessories such as coral, seashells, etc…to your freshwater aquarium.

Cloudy water

Probably the most common cause for cloudy water would be bacteria. In newly set up aquariums, free floating bacteria can make the water appear “milky white”. These are the bacteria that will eventually make their home in your gravel bed and filtration systems, forming the biological filter. They are not harmful to your fish and the water should clear up within 2 to 3 days.

Note: This can also happen in an established aquarium after a good cleaning. If the gravel or filter systems are cleaned too well, the existing bacteria will be removed or destroyed during the process. Not only might you experience the bacteria bloom, but it will also put the aquarium at risk of an ammonia flair up as well.

NEVER wash any of your filter media under the tap, only ever use old tank water for this job or you will kill off all the beneficial bacteria that is living in the media and therefore cause a high ammonia and nitrite reading.

Tiny particles of debris are another cause for cloudy water. Some can be so small that your filter system is unable to trap them, allowing the debris to pass right through. There are products available that will cause the particles to clump together, making them larger and more easily filtered out.

Floating algae is yet another culprit. At lower amounts, the greenish color may not be so apparant but its presence is still clouding the water. Frequent water changes will help to remove some of the algae and lower nitrate levels which can aid in its growth.

Sometimes your water may appear to be cloudy, when in fact it is not. Over time, a very thin layer of algae, tiny particles of debris and dissolved wastes can accumulate on the inside of the glass making the water appear somewhat hazy. Check the glass by looking through the aquarium from the end. You should be able to see this film that can be easily removed with an algae scraper or sponge.

Planaria worms

Found something living in your aquarium that is not a fish?

Well, don’t be alarmed. At one time or another most aquarists encounter those tiny white worms that appear rather suddenly and usually in large numbers.

These are Planaria, a flatworm that usually come about in tanks where there is excess food due to overfeeding.

They “glide” along surfaces such as the inside of the glass, ornaments and even the underside surface of the water, but are most noticed on the inside glass just above the gravel. These worms do not swim throughout the open water but can get caught up in currents and are expelled from one area to another where they will attach themselves to any surface they can.

They are not harmful, but unless removed through cleanings and water changes, they can accumulate to very large numbers. Should you discover these tiny white critters in your tank, cut back on the amount of food you feed your fish. Eventually, any that may not have been removed through your cleaning, will die off from starvation.

Another way to help eliminate them is to equip your aquarium with a bottom feeder such as a plecostomus. Not only will this fish help to keep your tank free of excess food, but it will also eat the planaria and any other uninvited guests that may be in your tank. Some fish such as tiger barbs, angelfish and most fry have also been known to eat these invaders, as you may have noticed that they sometimes “pick” at the glass.


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