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Aquarium Water Quality

Aquarium Water Quality - Cycling

One of the most important areas to address for care of your tropical fish is the aquarium water quality.  If you start with a brand new aquarium that hasn't had fish in it before, you will find that you get an ammonia spike soon after introducing your new fish.  This spike can actually burn the fins off your new fish, ultimately killing them and causing great disappointment.  It is difficult to resist filling up a new tank with fish, but the most important way to reduce ammonia is to start with only a few fish and add more after a few weeks.  Once you have an established tank, you can keep a larger number of fish with very little effort.

Nitrogen Type

Parts Per Million







The most efficient way to cycle or establish a balanced aquarium is to import your bacteria from another aquarium.  The main catch is to ensure the aquarium you use is disease free.  You can use an existing filter, gravel or plants.  If you don't have access to an established aquarium, resist the temptation to buy lots of fish a start with only one or two.  For an interesting article about a fishless cycle and ways to balance an aquarium, visit the Tropical Fish Centre.  There are test kits to test for ammonia, nitrites and nitrate levels.

Water Quality - Ammonia Spike

If your fish are struggling, test your ammonia levels with a test kit. If you have an ammonia spike, here are some things you can do to help correct the problem right away:

  • Do a 20% water change with dechlorinated water and continue to do this every day until the ammonia level drops.  The best ways to dechlorinate the water are to let it sit in a bucket a few days or to use a product like Seachem, which also removes ammonia.  Be careful with other chlorine removers as these can also kill the valuable bacteria you are in need of.

  • Test the water daily for ammonia levels.  If they remain high, you'll need to change more water.

  • Keep good aeration in the tank to help develop bacteria.

  • Avoid using medications, as these kill bacteria.

  • Don't feed your fish at all if your ammonia readings are high, as this will cut down on the ammonia that the fish produce.

  • Don't clean the gravel. You want to promote bacteria and gravel is an excellent location for this.

  • Don't change your filter material.  Allow bacteria to develop there.

Aquarium Water Quality - What is pH?

pH is an aquarium water quality scale that measures the “potential” of “hydrogen” – the number of hydrogen ions in water.  The scale ranges from 1 – 14.  The lower the number, the more acidic the water is.  The higher the number, the more alkaline the water is.  A value of 7 is neutral.  Most freshwater fish prefer slightly acidic water to neutral water in a range from about 6 – 7.5. Decaying plants can lower the pH.  If pH drops below 5, bacteria levels decrease to a point that wastes cannot be broken down and most fish will not survive. pH can be measured using a simple inexpensive test kit readily available at department stores.  The kits include drops that can be added to increase or decrease the pH level.  The drops are usually phosphate based and will encourage algae growth.  pH is difficult to lower in hard water.

Water Type pH

< 7


> 7

Aquarium Water Quality - What is dH?

dH is a measure of the degree of General Hardness of water based on the amount of dissolved calcium carbonate present.  General hardness can also be measured in ppm (parts per million).

Hardness (GH) dH ppm

Very soft

0 - 4

0 - 70


4 - 8

70 - 140

Medium Hard

8 - 12

140 – 200


12 - 20

200 – 350

Very Hard

20 or more

350 or more

Most fish can survive in a wide range of water hardness, however dH can be particularly important in creating proper breeding conditions.  Water can be softened by filtering it through peat moss, boiling it or by passing it through a reverse osmosis filter.  Water can be hardened by subjecting it to crushed coral or dolomite.  Soft water needs more monitoring as the pH level becomes very unstable in soft water.

Comments - Bogwood versus Driftwood

by LittleHippyGirl:

Bogwood and driftwood are the same thing. The only difference is that the first term is generally used in Europe, and the second in the US. The effects of driftwood could be good or bad, depending on your fish and water. They will leach tannins into the water to lower pH which can be helpful, but if your kH (pH buffer) is too low, it could cause the pH to suddenly "crash", and this could potentially kill the fish. By boiling it before placing it in the tank, it will reduce the tea color it may stain the water, but you still must monitor pH. My personal opinion on driftwood is that it is a beautiful, natural thing for an aquarium, but I prefer the fake stuff over real. Its much less messy, and Topfin makes some pretty realistic resin models.

Water Quality - Water Changes

It's a good idea to change some of the water in your aquarium on a regular basis, such as weekly.  This is especially important for species that require very clean water, like cichlids.  Here are a couple methods:

Aquarium Water Changes - The Bucket

  • Obtain two plastic buckets and fill one with tap water.
  • Let the water in the bucket sit for 2 or 3 days.  This will allow the chlorine to dissipate and is more effective than chemical water treatments, as those can kill valuable bacteria.

  • When you're ready to change the water, first clean the gravel with a gravel vacuum by siphoning into your empty bucket.  Do this until the bucket is nearly full and then discard the water.  You can buy gravel vacuums at most pet stores or Walmart.  It helps if you have a siphon pump to get things going.  

  • Next pour the new water directly into the tank.  No need to worry about the temperature as long as it was stored at room temperature.  Some of your fish may enjoy swimming against the current this creates.

  • To finish up, refill the bucket you use for the clean water, in preparation for the next change.

Aquarium Water Changes - the Python

The Python is made by Python Products and is a very popular method for performing water changes.  It uses tubing and an adapter to your water faucets, which allows you to add or remove water from your tank with very little spillage.  The downside is that you end up adding chlorinated water directly to your tank.  Our readers have found ways around this by adding de-chlorinators, like Seachem Prime, directly to their tanks before adding the tap water or by using powerheads to pump stored, purified water into their tanks.  The Python is available through many retail and online stores.  You can visit their website for further information through the link above.

The frequency with which you change the water will be determined by the number of fish and also the look of the water.  If it is cloudy from over feeding or from adding too many fish, make sure you've read the section on Water Quality.

It's a good practice to wash your hands before cleaning your aquarium.  This will prevent chemicals from being introduced to the tank from your hands.

Water Quality - Comments on the Python

Comments on the Python by Sharon:

The Python Syphon System works really well for large tanks. It hooks directly to the tap, and allows you to remove and add water by opening or closing the valve...it's easy! You do have to get the water the same temp. as the tank(I use a mixture from the hot and cold taps), and add water conditioner to remove chlorine.

Comments on the Python by Gillian:

I have a Python as well, and it is SOOO much easier than having around buckets and buckets of water in preparation for the water change. It's a lot faster too, and much easier on the back!! Definitely get yourself a Python, it is well worth the money.

Aquarium Water Quality - Seachem Prime

There are a number of products that can help you establish and maintain water quality.  There are test kits and additives to adjust the pH and dH water hardness.  Seachem Prime is a very popular additive for de-chlorinating and it controls ammonia levels too.   Here's an excerpt from the Seachem website about Seachem Prime:  "Prime™ is the complete and concentrated conditioner for both fresh and salt water. Prime™ removes chlorine, chloramine and ammonia. Prime™ converts ammonia into a safe, non-toxic form that is readily removed by the tank’s biofilter. Prime™ may be used during tank cycling to alleviate ammonia/nitrite toxicity. Prime™ detoxifies nitrite and nitrate, allowing the biofilter to more efficiently remove them. It will also detoxify any heavy metals found in the tap water at typical concentration levels.Prime™ also promotes the production and regeneration of the natural slime coat. Prime™ is non-acidic and will not impact pH. Prime™ will not overactivate skimmers. Use at start-up and whenever adding or replacing water."

Comments - Why Zeo-lite is Not Recommended

The following information has been submitted by "LittleHippyGirl".   Zeo-lite is a chemical that is widely available in fish stores for its ability to suck up ammonia like a sponge. There are other brand names, but any ammonia-absorbing chemical would fall under this category. One would think, "why is this so bad?" Well, this is why it can be.

  1. Once zeo-lite sucks up a certain amount of ammonia, it will not suck up anymore. There is no way you can tell how "full" the zeolite is until you suddenly have ammonia levels in the water and this could make your fish sick or weak. Granted, zeo-lite can be re-charged by soaking it in a container of salt water, its powers are not easilly monitered.
  2. You can NEVER add salt to an aquarium with zeo-lite. Salt is useful in many ways, treating many types of diseases, helping wounds heal, and of course its mandatory in aquariums with brackish fish. Like said above, any salt in the water will cause the zeo-lite to let go of all the ammonia, immediately causing highly toxic and dangerous levels in your aquarium.

  3. The most important downfall is that zeo-lite hinders the more natural nitrogen cycle. In a fully cycled aquarium, beneficial bacteria lives in the filter and changes ammonia into nitrite, and nitrite into nitrate. The first two are highly toxic, but nitrate is only toxic in higher numbers and this is reduced by vacuuming gravel and changing the water. In a fully cycled aquarium, the changes are so quick that the first two chemicals can not be detected in test results and your fish stay happy and healthy. However, zeo-lite will suck up the ammonia and starve the beneficial bacteria, crashing the nitrogen cycle.

Having said all that, zeo-lite isn't entirely bad. No, it typically shouldn't be used in the home aquarium, but there are some situations that zeo-lite can benefit your fish. Sometimes aquariums under 5 gallons have trouble keeping a nitrogen cycle stable. Another acceptable case would be a temporary aquarium, such as a hospital or quarentine tank. Sometimes spare aquariums need to be unexpectedly and quickly set up, and you can not borrow media from another aquarium to jump start the cycle. For these exceptions, empty the filter of any sponges, media, cartridges etc and add zeo-lite. Do monitor the ammonia level carefully, and frequently re-charge the zeo-lite in salt water. Keeping a lot of fish in an aquarium with zeo-lite will make this maintenence more difficult but even more mandatory. Remember, you can not treat fish with salt in an aquarium with zeo-lite.