The Elixir of Life - Water Changes


What would you say if I told you there's a liquid medicine out there that is guaranteed to keep your fish in optimum health, cost mere pennies per use, and is so easy to dose even a child could do it? You would probably call me crazy! Well, crazy or not, it exists and it's called CLEAN WATER! That's right, your fish love to swim in clean water.

Even though we fancy ourselves as Thoughtful Fish Keepers, what we really are is something akin to Water Keepers. We keep the water that the fish live in, that is our main job. We keep it filtered and clean, at the right temperature, and any other parameters the fish need. Except for feeding, the fish pretty much take care of themselves. How's that for a weird spin on the hobby?

We are really Water Keepers. Fish can take care of themselves!

In this article I will expound upon the benefits of doing water changes, dispel some myths about them, and give some ways to make it a little easier on you. I hope that this article inspires you, because once you keep your water well maintained... the rewards you receive will amaze you!

Benefits of Water Changes ... And Is It Necessary?

Water changes could be one of the most important things you do for your fish. You can buy all the best foods and whiz-bang products that are offered in the pet stores. But if your water is bad your fish will be unhealthy, guaranteed. It's a very simple equation... clean water = healthy fish.

You will see your fish become more active after a water change. They love it! Some fish will even play in the outflow of the water they're so happy. The long term effects of regular water changes are even more impressive. They will grow to full adult size, show excellent coloration, and live long and happy lives. The fish will rarely get sick, and there will be a much better chance that they will breed in your tank.

Water changes are the most important thing you can do for your fish

That all sounds good, but is it really necessary? YES! Tank water can build up in waste levels, even with proper filtration, so it is necessary to physically remove these wastes from the water. The only way to do this is by removing old tankwater and replacing it with fresh new water. There is some debate on whether it is nitrate itself which when found in excess causes fish to get sick and possibly die. Whether it is really nitrate or some other compound doesn't really matter. Nitrate is a substance which we can test for easily. So if nitrates get past 20 ppm, it is time to do a water change. Hobbyist's experiences across the country attest to the fact that keeping nitrates below this level helps maintain healthy fish.


No matter where we go in the world we run into myths. Some of them are grounded in a little truth, but taken way to far and canonized into some ultimate truth in the hobby. Others are propagated through ignorance and bad advice. Well don't worry, we'll dispel them all right now!

Myth #1: The value of "lived in" water.

Earlier in the 20th century the majority of fish keepers believed there to be something special in "lived in" water. You know, water that fish have been swimming in for a long time. They believed there was some sort of quality that made it undesirable to change it with fresh water from the tap. I'm not sure how this got started, perhaps it was back when people didn't have dechlorinator chemicals, so they needed to put their tapwater in buckets and aerate overnight in order to drive away the chlorine. Or maybe someone stuck their $50 discus in a goldfish bowl full of cold tapwater and didn't like the results.

This couldn't be farther from the truth. Fish enjoy and thrive in clean fresh (dechlorinated) water from the tap. In nature the water is continuosly being replaced, so most fish aren't used to high levels of wastes in their water. So then why would they want to live in dirty water? The cleaner the water, the better.

Myth #2: Large water changes are bad and stress your fish.

There is a little truth to this statement. If you leave your tank alone and don't do any water changes for weeks and weeks, the water chemistry changes over time. Fish wastes builds up and the pH of your water becomes more acidic. Making a large water change all of a sudden changes the chemistry rapidly and that can be stressful to fish. Another problem is if you make a large water change with water which is at a different temperature, as any rapid change in temperature could put the fish in shock.

So here's the whole truth: Large water changes are fine for fish if the chemistry of the fresh water is close to the chemistry of the replaced water. How do you guarantee that the fresh water you're adding is close to the old water? By maintaining a good weekly water-changing regimen, there should be no worries about changing a larger amount than usual.

Myth #3: Doing a large water change once in a while is better than frequent smaller changes

This runs counter to Myth #3 but it is still prevalent in the hobby. I think this comes from people just being lazy. Instead of doing smaller chores once a week, why not do a big chore once a month?

Changing 20% - 30% of the water once a week will have little chance of ever stressing your fish.

Please see the answers above for Myth #3 on why this is a bad idea. Large water changes are good, but only as part of a regular schedule. That's like saying it's better to let a bathroom go uncleaned for a year then scrub it all down with bleach detergent. That's fun for about a week after its done, then after that ... eww.

Myth #4: The water should only be changed when it's cloudy.

This is just ignorance, and maybe that's bliss for some people because they only have to change the water when it turns green, brown, or even yellow. Anyone who keeps fish needs to see the "unseen" in water through test kits and common sense. Looks can be deceiving. Besides, it must be obvious at some point (fish deaths) that something is wrong with this lack of maintenance.

There are fish wastes which buildup that the filter can't completely take care of. These need to be removed manually through water changes. Except through some fancy expensive filtration methods that are beyond the usual hobbyist, these wastes cannot be removed any other way. And they are not visible at all except through the use of test kits. A glass of ammonia and a glass of water look the same... which would you like to drink?

Methods of Doing Water Changes

#1 - Luggin the Buckets!

Don't vigorously vacuum more than half your gravel at one time, otherwise you may upset the bacteria colonized there and cause water to foul.

This is the method you can use if you have a small tank (10 gallons) and the sink isn't too far away. Usually this includes vacuuming the gravel with a gravel vacuum. A gravel vacuum is just a larger rigid tube which (when used properly) will not completely suck the gravel through the siphon hose you are using. You then rummage through the gravel with this and try to suck up all the nasties that have settled in the gravel. This is fish poop, uneaten food, and other gunk that we call "detritus".

Here are the steps:

  1. Turn off all the electrical equipment in the tank, except the lights.
  2. Fill the siphon hose with water, placing a finger on the end which will go in the bucket.
  3. Stick the vacuum/siphon end into the tank, and the end of the hose with your finger on it should go into the bucket.
  4. Take your finger off the end and make sure the siphon hose is resting inside the bucket and water is flowing out of it and into the bucket.
  5. Then proceed to move the vacuum/siphon end around the bottom of the tank, picking up gunk while sticking it into the gravel bed. (Warning: Don't vigorously vacuum more than half your gravel at one time, otherwise you may upset the bacteria colonized there and cause water to foul.)
  6. When the bucket is nearly full, stop the siphon by removing the vacuum/siphon end and let the rest of the water drain into the bucket.
  7. Dump the bucket of water wherever convenient (Hint: flower gardens and shrubs like fish water!) Repeat steps 2-7 as necessary until you have removed the appropriate percentage of water from the tank.
  8. Fill the bucket with fresh water from the tap at whatever temperature your tank is at. Declorinate the water in the bucket as per the directions on your dechlorinator.
  9. Slowly pour the water from the bucket into the tank, being careful not to disturb too much gravel and make a "crater" which is a hassle you'd have to fix later.
  10. Repeat steps 8-9 untill the tank is filled to within 1/2" of the top.
  11. Prime your filters, turn them on as well as the heaters.
  12. Check out your fish and see how happy they are with clean water!

#2 - Siphon to the Sink

This is similar to the bucket method except instead of a bucket you have a very long hose that attaches to the sink directly and produces a siphon through waterflow. It can then be turned reverse in order to fill your tank. Steps are slightly different but the idea is the same.

  1. (Steps to come!)


Well I hope this article helps you appreciate the importance of fresh water for your fishes health and survival. Indeed, once you start maintaining your tanks to the highest level of quality for your fish... they will reward you with excellent growth, optimum color, and perhaps even breed for you. Go do a water change today, your fish will thank you for it!