I have a 3 gal tank and noticed today that a layer of bubbles are on the top of the water. Today is the 1st day it has done this and it is not soap. I do have 2 live plants in the tank and have 2 orange molly's, a catfish, a neon tetra, and a black and white speckled molly. The filter is clean.

When bubbles form like that on the water surface, that is an indication of high dissolved organic levels in the water. You should do a water change when you see this condition but we have to warn you that your tank is over-crowded, so water changes alone may not help. You should have three inches of fish in that tank, and it sounds like you have about five inches or more.

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I am getting white blobs on my filter and aqaurium bottom. My water is clear and very little change in water clarity. I want to clean the tank. Can I transport the fish to another aqaurium while cleaning the one they live in?

You would be better off to leave the fish in their aquarium and try to find out what the problem is. Moving to a new tank is very stressful for fish, and you could wind up losing some or all in the move.

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I bought a new 10 gal tank set it up. I added fish and the water formed a white slime across the top film of the water after a couple of days. I cleaned the tank again, set it up and again white stringy slime occured and the water is dingy. What can I do?

Sure sounds like ammonia is building up in the tank rather quickly. We would say you either:

A) Did not equip the tank with enough filtration (for a 10 Gal that would be an undergravel filter and a hang-on power filter).

B) Are over-feeding.

C) You started with too many fish.

Don't feel bad. These are the most common mistakes made by beginners. Please read our articles. We have plenty of information there about all three of these possible causes.

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I recently moved my aquarium, and ever since I moved it, a thick film keeps appearing on the top of the water that I can scoop off with my net. I have circulation on the top of the water, but it gets think enough to stop the water flow in that direction.

That film is a complex of proteins produced by anaerobic bacteria that were in your gravel before you moved. We suspect that prior to moving the aquarium, it had not been cleaned for a while. You need to siphon all of it out of the aquarium. What is left after that can be removed by laying paper towels on the surface and lifting them off. This stuff is very dangerous as it can seal off the surface and deprive the tank of oxygen. If it continues to accumulate, you need to upgrade your filtration with a canister filter.

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What water quality parameters should I be monitoring?

For freshwater aquariums, we recommend testing the aquarium every two weeks at a minimum. Test for pH, nitrate and ammonia. You may also want to test for phosphates if you are using municipal tap water for water changes. If you keep live plants, you may also want to monitor CO2. (See our selection of test kits.)
Saltwater fish-only aquariums should be tested weekly for pH, nitrate, nitrite, ammonia, alkalinity and phosphate. Reef tanks should be tested for the same parameters, as well as calcium. Many saltwater aquarium hobbyists also monitor redox potential using a redox meter (ORP meter). Because of the lower dissolved-oxygen levels in saltwater, some hobbyists also measure oxygen using titration tests available on the market.

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How often should I test my aquarium water?

For all aquariums, regardless of whether they are fresh or saltwater, we recommend testing every week, or at least every two weeks.

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I tested my water and found low levels of ammonia. What happened and how can I correct this?

If this is a relatively new aquarium which has had fish in it for less than three weeks, this condition could be normal. Otherwise, either something is dead and decaying in your water, or you have done something to your aquarium which resulted in a loss of a substantial population of nitrifying bacteria.
Most bony fish produce nitrogenous waste in the form of ammonia (Most sharks, skates and rays produce urea as we do). Ammonia can also be produced as a by-product of the decay of detritus or dead specimens left in the tank.
In an aquarium, beneficial bacteria cultivate, usually in a filter or in the gravel, that oxidize the ammonia, first into nitrite, and then nitrate.
A new aquarium begins with no bacteria, so an ammonia test would yield positive results until a bacteria population exists that is large enough to handle ammonia production. If this is the case, time will heal this situation.
If a major portion of the bacteria population is removed, an ammonia test will yield positive results. This could happen, for example, by removing the gravel in an under gravel-filtered aquarium and washing it in tap water, or changing the filtration media in a wet/dry filter. If this is the case, you can try adding some ammonia neutralizers and/or commercial bacteria cultures. You can also try to obtain some established gravel (or live rock or sand for marine tanks) from another aquarium. Water changes will not help, and may make the situation worse. If these methods fail, all you can do is cross your fingers and wait for the bacterial population to bounce back. Luckily, nitrifying bacteria multiply very rapidly.
If the cause of the ammonia rise is due to decay, it is important to find the source of ammonia production and remove it immediately. Dead fish left in the tank are likely culprits. After removing the dead material, a partial water change should bring conditions back to normal.

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What is Redox potential? Do I need to worry about it and if so, how do I control it?

Let us start by saying that redox potential is really a saltwater thing, so if you have a freshwater aquarium, read on because we'll explain this soon, or . . . because you like the way we write. In our humble opinion, the redox potential of a marine aquarium is one of the best measures of success in maintaining a great saltwater environment. If we had our way, every salt tank everywhere would be equipped with a redox meter (ORP meter).
We'll start with our very own anthropomorphic, unique, over-simplified and only-partially-correct definition: "The redox potential of an aquarium is a measure of the aquarium water's ability to cleanse itself." Now here's the long chemistry-lesson version. You'll soon understand why we gave you the simple version first:
With the exception of energy, everything, everywhere, that's anything at all, is composed of atoms. An atom, you may recall, is composed of protons, neutrons and electrons. The protons and neutrons form the center of the atom, called the nucleus. Protons carry a positive charge, and neutrons are neutral, so the nucleus has a positive charge.
There is one negatively-charged electron for every positively-charged proton in an atom. The electrons circle the nucleus in layers or shells. It is the electrons in the outer shell that "react" with electrons in other atoms to form compounds.
The more protons an atom has, the heavier it is. Atoms with different atomic weights are known as elements. Hydrogen is the lightest, having one proton. Oxygen is next with two protons. An element is made of one or many identical atoms. When two elements combine in a reaction, they form a compound. Compounds may exist as molecules or ions. Molecules are un-charged components of a compound. Ions are either negatively or positively-charged components of a compound. The simplest molecules are two combined atoms of one element, for example, oxygen as O2, or chlorine as Cl2.
"Redox" is short for oxidation-reduction, which is a type of chemical reaction. A redox reaction occurs when two elements combine, and one element "loses" an electron to the other element. The element that "loses" an electron is said to be "oxidized." The element that "gains" an electron is said to be "reduced." By the way, the electrons aren't really lost. They're shared in such a manner that the resulting molecule has an electrical charge. For example, when two sodium atoms (Na), and a chlorine molecule (Cl2), combine to form two molecules of table salt (2NaCl), they undergo a redox reaction. The sodium is oxidized and "loses" an electron, so that it has a positive charge. Chlorine is reduced and "gains" an electron, so it has a negative charge. The two go hand-in-hand. If one element is reduced, another must be oxidized.
Some atoms, like chlorine (Cl) and oxygen (O), really "want" to "gain" electrons. These atoms are called oxidizers. Some atoms, like sodium (Na) and Hydrogen (H), really "want" to "lose" electrons, and are called reducers. Water is an amazing molecule. It too, is formed by a redox reaction, which forms a bi-polar charged molecule, having a positive charge on the hydrogen end and a negative charge on the oxygen end, making it both an oxidizer and a reducer at the same time.
"Potential" refers to the charge of an ion created a redox reaction and dissolved in water. When table salt (NaCl) is dissolved in water, it forms two ions. One is an oxidized positively-charged sodium ion, (Na+), called a cation (+). The other is a reduced, negatively-charged ion, (Cl-), called an anion (-). The oxidation reduction potential of saltwater is the measurement of the total cations and anions in solution that are available to either oxidize or reduce other molecules. Redox potential is measured in millivolts (mV). If there were an equal amount of cations and anions dissolved in a given volume of seawater, the water would have a redox potential of 0.0 mV. Water in an aquarium has plenty of free oxygen in it (we hope!). Oxygen is a great oxidizer, and is busy "stealing" electrons, so there are always more positively-charged (oxidized) cations present in clean seawater. Therefore, saltwater in an aquarium will have a positive redox potential. The ideal redox potential in a marine aquarium is between 350.0mv and 400.0mv.
If the oxygen levels drop in an aquarium, more anions appear on the scene, and the redox potential will fall. This happens as organics accumulate in the water, reducing oxygen. If a strong oxidizer, such as ozone (O3), is introduced, the concentration of cations increase, and the redox potential will rise.
By measuring the redox potential of the water in a marine aquarium, we can tell how clean the water is. A redox potential meter only measures redox potential. A redox meter/controller not only does this, it also can be set to maintain a desired redox potential by controlling an ozonizer which doses ozone into the water, usually inside a protein skimmer or an ozone reactor. Ozone is such a powerful oxidizer, that caution should be exercised when using it. It is also used in aquariums to control un-wanted pathogenic microorganisms and parasites.

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I just bought a 5 gallon aquarium, I was wondering if it's better to use tap or spring water?

Tap water is fine, provided you use a good water conditioner, such as Stress Coat, Novaqua, Kent Pro-Tech Coat, or Safe.

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I just bought a 2 gallon aqua tank w/air pump,hood light and undergravel filter. I'm planning on buying goldfish, how many do you think I should buy and what type of water should I consider using tap or spring water?

In two gallons of water, one goldfish is pushing the limit! Consider keeping a single Betta, or a couple of White Cloud Minnows instead. Each Goldfish truly needs five gallons of water to survive for any length of time. Tap water is fine, provided you use a good water conditioner, such as Stress Coat, Novaqua, Kent Pro-Tech Coat, or Safe.

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Frequent Aquarium Questions