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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. First read the article by Bernie below for advice on Cycling a New Aquarium Tank. You can buy 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.

Benefits of Indian Almond Leaves

by David Girard:

Read about the Benefits of Indian Almond Leaves For Your Pet Fish. David explains how Indian Almond Leaves can condition water, lower pH, accelerate healing, encourage breeding and create a blackwater environment.

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:

Water Quality - When to Use Salt

Comments on When to Use Salt by Bernie:

Aquarium Salt can be used as a medication as it can aid the promotion of a fishes slime coating (which protects them from disease and conserves their energy), it can also relieve stress in fish, help in healing wounds and be used to help eliminate parasites (using a salt bath). It can sometimes help to lower nitrite. Any salt used should be free of additives such as iodine.

Freshwater fish do not need the addition of salt in their tank or to use it as a preventative measure (if used constantly, parasites etc. become immune to the salt and it becomes ineffective). It should only be used as a medication when the need arises. Salt also doesn't evaporate, and can only be removed by water changes. Plants will not survive with higher concentrations of salt as well.

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, you will need to change the water more often.

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'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 then 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.

Cycling a New Aquarium Tank by Bernie

There are 2 ways to Cycle a new tank, either with fish, using their waste products to help create ammonia or without fish (which is called Fishless cycling). You must always cycle a new tank!

What is Cycling?

Cycling is a little complicated, but it's very important to know when you own an aquarium. With a new tank/filter, you do not have enough beneficial bacteria to remove ammonia from the water, so if you aren't careful your fish could die. Cycling a tank is basically breeding a bigger colony of beneficial bacteria to convert the amount of waste your fish produces and any decaying food. There are two types: one converts ammonia to nitrite, and the other converts nitrite to nitrate. Buy a test kit to monitor the levels of these three to see how far along your cycle is, and to make sure they don't reach dangerous levels for your fish along the way. While the tank cycles, you should see a spike of ammonia and it will go down, then a spike of nitrite and it will go down, then nitrate will start to increase. Do not rinse the gravel or anything in the filter in tap water or the chlorine will kill the beneficial bacteria.

Three Phases for Cycling a New Aquarium Tank

1st Phase: The cycle starts as soon as there are fish in the tank or you start feeding the tank (if using fishless cycling). The waste products, & any uneaten food, break down into either ionized or unionized ammonia, which usually starts to form around the 3rd day after putting fish in the tank. The ionized form, Ammonium (NH4), can be present in a pH below 7, and is not usually harmful to fish. The unionized form of ammonia (NH3), exists in a pH of 7 or above, and this ammonia is highly toxic to fish & any amount can be dangerous, but if levels reach 2 ppm, the fish start to stress & will suffer. P.W. changes are the best way to stop high levels of ammonia forming.

You usually need to test for ammonia from the 3rd day. Check everyday from then on until you see it start to drop. Then you continue testing every 2nd day until it remains at 0.

2nd Phase: This is where the ammonia starts being eliminated by the Nitrosomonas bacteria, this process is what produces the nitrite, which is also highly toxic to fish. Nitrite levels of 1 ppm can be very harmful to some fish. Nitrite usually appears at the end of the first week after adding fish, (but can take longer to start), which is when you should start testing for nitrite, & keep testing every 2nd dy until it reaches 0. Again partial water changes will help keep nitrite levels down.

3rd Phase: This final phase of cycling can happen very suddenly. In the 3rd phase, Nitrobacter" bacteria change the nitrites into nitrates. In moderate levels nitrates are not too harmful to fish. An acceptable level is 5 ppm, but can be as high as 30 ppm before it starts harming fish. Don't leave it that high if it does get to that level. In a cycled / established tank you should normally get a nitrate reading that is between 5-10 ppm. Partial water changes will keep levels down if they get too high. Once the tank has been established you only need to check the nitrates every 3 months or so.

Once you have a constant reading of ammonia = 0 nitrite = 0 nitrate = 5 ppm for a couple of days, you're tank has finished cycling.

Cycling a New Aquarium Tank - With Fish

When setting up an aquarium, buy some hardy fish (definitely not neons) to get the cycling with fish started. These fish are often called "Starter Fish" & the purpose of these fish is to provide ammonia through respiration, fish waste, and decaying food. The ammonia allows the first set of nitrifying bacteria to colonize and to initiate the cycling of the tank.

During this time of cycling with fish, ammonia and later nitrites will spike up to dangerous levels for the fish. So, after 3 days of adding the fish, you need to monitor these levels daily & do partial water changes every 2 to 3 days. Partial water changes may be needed every day if levels get too high. Also cut back on feeding or stop feeding for a day of two. Some fish may not survive the cycling process, so it is best to be prepared for some losses.

Cycling with fish is complete as soon as ammonia and nitrite levels are no longer measurable, consistantly remain at 0 and you have a nitrate reading as mentioned earlier. This form of cycling takes anywhere from 4-8 weeks.

Cycling a New Aquarium Tank - Fishless Cycling

For Fishless Cycling, you need to set up the tank with gravel, a filter and water. Use a heater to maintain a temperature at around 80 F, as bacteria grow faster in higher temps. Add cheap fish flakes daily and siphon every two weeks just as if you had fish in the tank. Keep monitoring the levels of ammonia, nitrite and nitrate.

Once your nitrogen cycle is fully established during fishless cycling, do a series of water changes over a few days. Then add your fish. This way you can add more at a time and none of the fish will be harmed from ammonia or nitrite levels. The fishless cycle is much less work. It's also less stress on your and your tropical fish.

Cycling a New Aquarium Tank - Seeding the Tank

Seeding the tank can speed up this process. Seeding basically means the introduction of existing bacteria colonies into a new tank. The decaying food will provide ammonia for these colonies to settle and grow in the new tank. This method also takes 4-8 weeks.

A Second Way to do a Fishless Cycle

There is also a second way to do a fishless cycle which requires a bit more effort. Instead of using fish food for ammonia production, you can also introduce pure ammonia to the tank. Add 5 drops of ammonia per 10 Gallons into the water on a daily basis. Ammonia will rise to 5 ppm and higher. As soon as you can measure the nitrites, reduce the ammonia to 3 drops per day. Nitrites will rise to similar levels. Keep adding 2-3 drops until the measurements of ammonia and nitrites come out with 0 ppm. The tank has then completely cycled.

Fishless Cycle - Phosphate By-Products

With the fishless method, when the fish are introduced into the tank there is a risk of creating by-products such as phosphates, which occurs by decaying food. The ammonia produced might not be sufficient to create enough bacteria colonies to hold the fish when they are introduced. This will trigger another growth of bacteria with the spikes in ammonia and nitrites. These re-renewed spikes however will be much shorter and less intense compared to the initial ones experienced during the primary cycle. Consequences for the fish are minimal, making this at least fish-friendlier. This method is usually quicker taking approx. 2-3 wks, but it can vary.

Cycling a New Aquarium Tank - Points to Remember

  • A tank may become cloudy during cycling which is normal, it is usually caused by a bacterial bloom as the bacteria establish/colonise and usually will clear up on its own.

  • The tank needs to be well oxygenated as the bacteria require oxygen.

  • If using ammonia cycling, the ammonia used should be free of any perfumes and additives. Just in case, use activw carbon to remove any traces of additives after the tank has cycled.

  • Do not treat the water with conditioners that remove ammonia.

  • Water changes are only necessary if the ammonia and nitrite levels are too high, which should only occur if more than 5 drops is used per 10 Gallons of water.

  • After stocking your tank with fish, general maintenance of the aquarium is all that is required. The bacteria will adjust to the fish load and if you plan to add more fish the bacteria will need to adjust again.

  • Remember that a tank has cycled if ammonia and nitrites are back at 0 ppm. At this time you can stock the tank with fish. If no fish are introduced, the bacteria will still need to be fed.


The Nitrogen Cycle by LittleHippyGirl

The nitrogen cycle can be a confusing thing, but it is something all aquarium owners should know about. I'll start at the beginning. Waste excreted by fish is released as ammonia. Ammonia is very toxic to fish, and even the tiniest bit can kill or sicken them. I have a betta that almost died from .1% ammonia. He was badly stressed the week before though because he jumped out of water for 5 minutes during a water change. In a mature and cycled tank, there are lots of beneficial bacteria.

Types of Beneficial Bacteria

There are two types of beneficial bacteria: 1) converts ammonia into nitrite, and 2) converts nitrite into nitrate. Nitrite is also very toxic to fish, and nitrate is only toxic in high numbers. If you have a planted aquarium, most of the nitrates will be sucked out of the water and used as plant food. If not, your fish rely on you to do water changes to keep nitrates under 20-30ppm. In a fully cycled tank, test results will always yield ammonia: 0, nitrite:0, and nitrate: higher than the tap water. A cycling tank will show ammonia and/or nitrite like your tank does.

Breeding Beneficial Bacteria

Now, tap water has very very little beneficial bacteria. There are not enough bacteria in tap water to make a safe and stable environment for fish, but there are enough to breed. Cycling a tank is pretty much breeding beneficial bacteria. Now how do you do it? Easy! Ammonia is "food" for the beneficial bacteria. Just like any other animal, if there is food, there is reproduction. They will keep reproducing until a balance is reached between "population" and waste production.

Cycling your Aquarium Takes Time

The only problem is that this can take about 1.5 months and while your tank is cycling, water params will likely be high and your fish could suffer. This is why it is imperative to closely monitor the water levels and do very frequent small water changes while cycling a tank. It's easier to start out with only one or two small fish than a tank's full capacity. Understand all that so far? Okay, now here are some shortcuts and pointers.

Beneficial Bacteria Grows Everywhere

Beneficial Bacteria grows everywhere...the gravel, the ornaments, even the glass walls! BUT, the filter is the hugest colony of all. That is really the point of the filter: to colonize beneficial bacteria. What kind of filter do you have? Does it have a cartridge or a sponge? Do you use bio-max or bio-balls? If you are not using either of those two things in your filter and you have even the slightest amount of space in your filter, I suggest you buy some. These will colonize huge amounts of bacteria If you just have a cartridge or sponge and no room for those things, you must be very careful.

Do not overstock your aquarium, and never ever replace or wash your cartridge. EVER! There is probably chlorine in your tap water, and by washing the gunk from the cartridge with this water, you are killing all of the beneficial bacteria and your cycle will crash. Replacing it with a new one will also crash your cycle. Even if the filter box says to replace the cartridge, do not do it because they do not care about your fish, only money. Cartridges will last a VERY long time, and you can safely wash them by swishing them in a bucket of dirty tank water after a water change.

Do not use ammonia-chips/zeo-lite in your tank. This will disrupt the cycling process and they can be dangerous if they are not used properly.

Prime Water Conditioner

Prime Water Conditioner is a miracle in a bottle. This stuff not only removes heavy metals and chlorine, but it also detoxifies ammonia and nitrite without disrupting the cycling process. This will come in handy a ton if you are cycling with fish, and it's perfect for dosing the tank in between water changes.

Seeding Beneficial Bacteria from Filters

Now, I think this shortcut will help you a bunch! The filter and media inside the filter on your smaller tank is most-likely loaded with bacteria. Hook that filter onto the bigger tank and move your fish to that tank as well. There may be a small bump of ammonia and/or nitrites, but other than that, this tank will be virtually cycled. It will be safe to remove the smaller filter in 2-3 weeks and your cycle will be complete.


For future reference, there are more humane ways to cycling than from scratch using a fish like you are trying to do right now. If the fish survive, they will probably be especially sensitive to poor water quality and illness, and may die an early death. If you do not have another filter to "seed" with, there are other options. One is Bio-spira. This is basically hibernating bacteria that can be bought to jump start the cycle and your fish will not be harmed. There are other brands, but this one has the highest success rate.

Fishless Cycling

Another idea is fishless cycling. In summary, you use an alternative form of ammonia to cycle the tank, adding no fish at all until the tank is ready. I think I've spoke enough already lol.

gH and kH

Oh yah, gH and kH don't have to do with your cycle. kH stands for Carbonate Hardness, and this is what buffers and stabilizes your pH. A high kH is almost always a good thing. gH stands for General Hardness, and that means how hard or soft your water is. The preference depends on the type of fish that you own. There are two ways of measuring kH and gH (like American inches and metric cm).