Aquarium Care, General and Beginner, Water Chemistry

Old Tank Syndrome

Periodic water changes are crucial to the wellbeing of your aquarium. As fish eat and poop, nitrate (fish waste) will accumulate in the water. Each water change that you perform lowers the nitrate concentration. Between each water change nitrate reaccumulates. The rate at which nitrate accumulates will vary depending on the number/size of fish you have and how much is fed. 

Nitrate is the product of ammonia and nitrite being broken down by good bacteria. Thankfully nitrate is less harmful than both of these, but it can get to a point where it can negatively affect your tank. In the event that proper water changes are not being performed as often as they should, “Old Tank Syndrome” can occur. 

Nitrate is acidic, and as such can impact your pH. Thankfully alkalinity is the buffer that helps protect your pH from fluctuating. When nitrate is very high, it will start to impact your alkalinity buffer. When the alkalinity is low (or zero) pH now has the ability to be impacted by other environmental factors. The acidity of nitrate will start to drop the pH of the aquarium water. 

A few reasons to be concerned:

  1. When nitrate levels are too high, certain fish may become ill or perish, while others who are hardier may put up with it. Oftentimes giving a false impression of the health of the tank.
  1. When nitrate causes the pH to drop it adds another stress that many existing fish cannot adjust to. Loss of appetite and color are common symptoms.
  1. When the pH is too low the good bacteria can start to die off. This results in high ammonia, high nitrate, high nitrate, AND now low pH all at the same time!

While some fish still somehow stay alive during this process, it is by no means a healthy scenario. The ones that tell you first are often the new fish you try to add. Adding new fish from healthy water into an aquarium experiencing Old Tank Syndrome, that have not had a chance to slowly adjust to the poor water conditions, often results in losses of the new additions.

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It is too easy to fall into the frame of mind that “My water looks clean and my other fish seem fine and healthy.” This is unfortunately not a reliable way to gauge the health of the tank. 

We recommend regularly testing your water chemistry (we do it in store for free). Oftentimes if you check it 2-4 times a year, many of these issues can be caught and addressed before they become a major problem. Although we would prefer that you test your water more often than that, we know that life happens and a fish tank is not always at the forefront of our minds. Just know we are here to help! 

If you feel like you may be encountering “Old Tank Syndrome” please give us a call. We prefer to work one-on-one with you to get you on the right track. 414-543-2552 

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