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Aquarium Maintenance: Water Changes

Freshwater aquarist with 30 plus years of experience. Breeder of several freshwater species of fish.

Changing the water is a vital part of aquarium maintenance!

Changing the water is a vital part of aquarium maintenance!

The Importance of Changing Water in a Fish Tank

I hate it when I'm in the pet shop, and I see someone buying an aquarium and all the stuff to set it up with, and they get the fish at the same time! I have to ask that person if they plan on setting up the aquarium and dumping those poor fish into it all on the same day.

If they say that they are, I give them a short lecture on aquarium cycling. I always suggest learning all you can about aquariums, fish, and how to take care of them before you buy anything.

Think about the home aquarium for a minute. It is out of place in our landlubber homes. It is a world of its own. Just like an underwater city surrounded by a giant glass globe would be out of place in the ocean. The biggest problem with an aquarium, in my opinion, is the lack of a natural water flow. In the oceans and rivers where all these little fish come from, they have a constant flow of fresh water. There are some exceptions but let's stay with the majority.

Why Change the Water?

The moving water keeps fish waste and other toxins from collecting in one area for too long. In the aquarium, we can circulate the water with filters and bubbles of air to help the exchange of gases, like oxygen and carbon dioxide, and keep the water from becoming stagnant. Filters remove a good amount of waste from the water but can't do the complete job by themselves.

We have to look at it from a biological level. Once you have a better idea of certain biological and chemical processes in an aquarium, you will see why you must cycle a new aquarium and do those weekly water changes that nobody likes to do.


Introduce New Fish Slowly

The aquarium has been set up and filled and is looking good! Before you add dozens of fish, the tank needs to be cycled. Fish produce waste like any other living creature. They excrete waste in both liquid and solid form. These wastes have to be removed to keep from killing the fish. Let the new aquarium just sit for a few days but keep your filter running. Two or three days will be plenty.

While you are waiting, research the types of fish that are available, and decide what you want to start with. Some types of freshwater tropical fish are easy to care for, and some are difficult. Start out with the easy ones. Go and buy two fish of your choice. Float them in their bag for at least 20 minutes, then add them to your tank. Wait about a week, and then add three more. Why introduce the fish so slowly? Bacteria need to grow in the tank.

Two Types of Necessary Bacteria

There are basically two types of good bacteria that you need in your tank. They will develop on their own in time. One type of bacteria breaks solid wastes down into ammonia and nitrite. The second type of bacteria will break the nitrite down further into nitrates. Ammonia is very deadly to fish. They can't tolerate much of it at all. Nitrites are less deadly but still not very tolerable. Nitrates are not nearly as deadly but will build up over a period of time and can kill the fish.

Adding fish over the course of a few weeks to a couple of months will give the bacteria time to develop. The more fish you have, the more bacteria are needed to break down the fish waste. There is a fishless method of cycling that I will not go into at this time but will write about in another article another day. You can get additives to help with the process too. One such product is called Bio-Spira. Stress Zyme is also a good one to try. They can help establish your tank as long as you still take it slow.

How Often to Change Water

The sound of water trickling in your new aquarium has a soothing effect on your soul as you watch the fish swim and play gracefully in their own little world. It takes you away for a little while. Aquariums are very beautiful, but there is also a little work to be done.

You are going to have to do some water changes; you will need a bucket and an aquarium siphon vacuum with at least a six-foot hose. Math is required for this task. Change 10 to 20 percent of the aquarium water weekly. A 20-gallon tank would require you to change 2 gallons of water weekly or 4 gallons if you do 20 percent. One of my aquariums is 44 gallons, and I change 5 gallons of water a week at least.

Remember those nitrates that are the end result of the bacteria breakdown we talked about earlier? Water changes keep nitrate levels to pretty much zero if you do them regularly. While you are siphoning water, you take the vacuum end and move it through the gravel to pick up large solid waste and suck it out into the bucket. All this results in a healthy and clean aquarium.

Be sure to add dechlorinated water of the same temperature back into your aquarium. That nasty water you siphoned out of the aquarium makes for some real good fertilizer for plants. My roses love the stuff!

Use Tools to Simplify the Task

If you don't like wagging buckets around, they do make this thing called a Python No Spill and Fill. This thing comes with a 25-foot hose, and you can buy additional sections to make it as long as you need it. The hose connects to your faucet, and the water pressure from the tap causes suction on the aquarium end. I have only one thing against them, which is the fact they waste water. After you finish removing old water and gunk from the aquarium, you flip a handle and run clean water into the aquarium.

If you search around, you can find electric water siphons too. They make everything now, it seems. Whatever method you use, just remember to do it on a regular schedule. Some hobbyists will do a 25 percent water change every two weeks. That does work well for larger tanks, in my opinion. For anything under 25 gallons, I prefer weekly water changes.

Someone asked me a while back what I thought about the conditioners that let you do water changes every six months. I did try this in one of my tanks just to see if it works. To my surprise, it did a decent job. You have to make sure you keep the filters clean for sure. One other drawback is the price. You have to add this stuff every week, and it isn't cheap. I have been in the hobby for over 30 years, and to be honest, I prefer the weekly water changes. It gives me a chance to get up close and personal with the hobby I enjoy so much.

A Bristlenose Albino Pleco (Pleco Love Algae)

A Bristlenose Albino Pleco (Pleco Love Algae)

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


Don Pratt (author) from United States on November 21, 2018:

Thank you !

Don Pratt (author) from United States on May 18, 2011:

Thanks John Sarkis, Nice to meet a fellow hobbiest! I liked your hub about aquarium basics!

John Sarkis from Winter Haven, FL on May 18, 2011:

Nice hub - voted up