Top 10 Mistakes New Fish Owners Make – #8

The #8 Mistake – Worrying Too Much About Algae

I’m very sorry to have to tell you that if you have fish in water, algae will grow. There is no way around it. Fish produce the perfect fertilizer for algae, nitrate. You may not be able to avoid it, but there are ways to mitigate it.

However, remind yourself that fish don’t care about algae, people do. Just because your tank is a little bit green does NOT mean that you are a terrible fish parent. It means your tank is healthy! But this does not apply to a tank so thick with slimy green scum that you cannot even see your fish.

Algae is a single-celled plant that can replicate very quickly. It may clip together with similar cells to produce hair or string algae, or it may stay singularly suspended in solution. During the daylight hours, algae converts sunlight and carbon dioxide into oxygen and water, a process known as photosynthesis. However, once the sun goes down, the algae start to use the oxygen in the water to respirate, converting oxygen back into carbon dioxide. This can produce respiratory acidosis, where the carbon dioxide levels start to drop the pH. In tanks that are very, very green, the algae can out-compete with fish for oxygen AND start to decrease you pH. As long as you kH or alkalinity is sufficient, your pH will not drop drastically. Having sufficient aeration in your tank will make sure there is plenty of oxygen to go around.

So, how do you keep algae from getting out of control?

  • Keep up with your regular water changes. Algae uses nitrate as a food source, so by limiting your nitrates by doing regular water changes, you will keep your algae in check.
  • Try to minimize direct sunlight on your tank. Not only will it keep your temperature from spiking, removing sunlight will help keep the algae from growing too quickly.
  • Scrub your tank walls regularly. Once the algae is loosened and sent into the filter, it will die from lack of sunlight.
  • Out-compete the algae with aquatic plants. Aquatic plants work the same as algae, just on a larger scale. For everything you want to know about aquatic plants, check out our webinar on Plants in Fish Systems. They will not rectify the entire problem, but will give minor assistance.

What should you not rely on?

  • Chemical additives are rampant on store shelves. These have NOT been tested on all species of fish. They are NOT controlled by any governing body.
  • UV lights only catch particulates in suspension. They will have NO affect on any algae trapped to the sides of your tank. But they will help zap it if you scrub.

Need help cleaning your tank properly? Check out our How-To video!

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pH and kH

It’s time for everyone’s favorite topic: water quality!

Many of our clients purchase “master” test kits which include: ammonia, nitrite, nitrate, low and high pH. This is a great collection of parameters to start with, but what about kH?

For those of you unfamiliar with kH, kH measures the buffering capacity of your water. Buffers bind to free hydrogen ions (H+) and keep them out of solution. Since your pH is a direct measure of [H+] in your system, kH directly impacts pH. And remember that high [H+] = more acidic and low [H+] = more basic.

(For those of you who are confusing this with gH, or total hardness: gH measures the amount of calcium and magnesium in your water. Although this may be a component of your kH, they are separate parameters entirely.)

So, if your kH levels are too low, all the H+ your fish discharge due to metabolic processes can build up and crash your pH. Adequate kH levels will keep your pH consistent throughout the day, regardless of what your fish and filters are doing. Knowing your tanks kH is an essential component to any fish keeper’s database. There are simple tests available that will make your testing a true “master kit.”

A kH value of >50 mg/L is adequate, but >100 mg/L is better. 

If your tank kH is low, test your source water kH. Some city and well systems have low kH coming in and will need buffers to be manually added to your system to maintain adequate levels. Keep an eye on your pH when manually adding buffers in order to make sure your pH will not change too much. Slow and steady is the goal for any pH changes.