Random Bits of Projects

December 31, 2008

Adding Salt to a Freshwater Aquarium

(Last post of the year!  Happy New Year!!!! I hope 2009 brings health, happiness, and security (in manyfish-blue-alhi2 forms) to everyone.)

The other day I was researching how much salt to add to our main freshwater aquarium containing an adult Black Ghost Knife fish (1/2 teaspoon/gallon or a little less for an adult) and remembered a common mistake people new to the hobby tend to make. (Yay! Something to post!)

Common Mistakes (in no order):

  • Using the wrong salt
  • Adding salt to the tank the wrong way (directly to a filter or dumping in directly all at once)
  • Adding too much salt after a water change

Adding a small amount of salt to a freshwater aquarium is often a good idea, especially if you do not have live plants. It keeps bad bacteria down, controls some of the unwanted worms, provides things many fish need in their system that tap water does not provide, and much more. It is also generally a must for fish like Mollies and crayfish.

Recently I noticed a bacteria infection starting up in our 55 gallon tank containing our Black Ghost Knife and various tetra. The Cardinals (look similar to neons, but with more red/less white) were getting cloudy eyes, fin rot, and very distressed. They tend to be one of our “Canaries” of that tank by reacting first to a problem that is starting. Water quality checked out fine so I figured it was bacteria. Melefix (great stuff usually) is often a good solution but the knife is sensitive and if you can avoid medicating, it is better. So I added the salt and the problem cleared up in about a week (did not remember to take not of exactly how long-sorry).

Tips on how to use Salt:

There is always a range of opinion on adding salt and how to do it. I will list what has worked for me and you can decide for yourself. I do not claim to be the know-all of fish keeping.

What kind?Never use table salt (people salt). It has stuff that is bad for fish. The least expensive way it to get Kosher rock salt. No additives such as Iodine. Or you can get aquarium salt (the easiest but expensive). There is controversy on whether you should use salt for marine tanks. I have had luck but there are things in it that may not be the best for your particular fish. So the less stuff in the salt, the better.

How Much Initially:  Generally it is around 1 teaspoon/gallon for many tropical, freshwater fish. But this is not always the case and I suggest asking someone who knows specifically about your fish or research it. (Not me!) For very sensitive fish like “scaleless” fish such as various Knife fish and peacock eels, you should add less. When in doubt, always add less than you were told. More is not better. Salt is great but only in small doses.

Only add salt to well established tanks! If you are setting up a new tank, do not do this yet. You need to get the good bacteria growing and deal with water quality fluctuations that go with setting up a tank. Once it is stable, then add it. Also, if you can get  your tank stable (with your fish in there too. 😉 ), then you have passed the first step in fish keeping if you are new.eel-in-skull1

Adding:  Do not add in one lump to the tank. You will have pockets of highly concentrated salt until it dissolves. The fish do not know to stay away and you kill some good stuff in the tank. Dissolve the salt in a bucket of dechlorinated water first (especially for rock salt). Add a little at a time through the day, depending on how dilute you have it. It lets the fish adjust and you do not shock the system. My husband was so paranoid (he loves his fish), it took him 4 days to add the salt. That is overkill. You can do it in a day, even in a few hours. If you notice your fish are not reacting well, you may have way too much salt. Again, when in doubt, use less. As you get more experience, you will have a better feel for how much to add and how fast. Caution early is better than trying to save your fish later.

Do not add it to the filter, thinking this will let it dissolve away from the fish then trickle into the tank slowly. It sounds like a generally good idea and I have made that mistake in my early days (oops), but avoid it. It kills the good bacteria that you finally have gotten to establish in there. You may end up going through “New Tank Syndrome” again. Dissolving it in a bucket first also allows you to better control how much gets added.

Adding after a partial water change: This is where I saw the most problems. You do not add the same amount of salt to your tank each time. Remember that the salt you add is dissolved evenly throughout the tank. When you remove water while cleaning the tank, you are removing the proportional amount of dissolved salt. This means there is still salt in your tank. I have seen many people do a partial water change and then add salt back in as if they had removed all of the salt. They then end up with way too much.

Also, salt does not evaporate. So if  you are adding water due to evaporation, you do not add salt too. You only refresh the salt after you, yourself, removed the water, not evaporation.

Calculating:  So lets say you added 10 teaspoons of salt to your tank initially. If you do a 10% water change, then you only need to add 1 teaspoon of salt back. Write down how much salt the tank needs overall so you remember later. After a water change, punch in the number of total teaspoons you need in the tank into a calculator, then multiply that number by the per cent of water you removed (0.1 for 10%, 0.25 for 25%, 0.5 for 50% and so on).  That shoud provide you the number of teaspoons (or whatever measure you use) you need to add back. Since the amount of water you remove is often an estimate, try to be conservative. If you are not exactly sure on how much water was removed, decrease the amount of salt you add to be safe. It does not have to be exact, just not horribly over.

If done right, you can prevent many problems from cropping up. I even think the water looks more clear but that might be in my head.

Plants:  I do not know if it is good to add the salt if you have plants. I have with Java fern but that stuff is tough. I also have a mystery sword plant that is doing OK with it. You may want to forgo the salt until you know for sure. I do not keep many live plants in my tanks, though I think they are fantastic.

Thanks for reading! 🙂

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