Can you change out too much water?

I had some nitrite in my tank that I have been working to keep at .25 and it was level with my ammonia. I've been testing my water twice daily and changing out the water accordingly. I noticed they were going up and I couldnt tell if it was at .5 or 1 ppm on the nitrite so I performed roughly a 75% water change to make sure it didnt get too high in case it was at 1. I waited about 4 hours and just checked the water again and my ammonia and nitrites are at 0 and my nitrate might be 0 but its not the same color yellow as on the chart (API test kit) it looks like it is starting to go a little gold but not orange like the 5ppm shade.

I dont know if it takes longer than I waited for the bacteria that is building in the filter and in the drift wood I have in the tank to fill the water again before I'll get readings or if I just screwed up.

You can't change too much water - you can do a 100% water change (given your media in the filter isn't left out to dry for long). The beneficial bacteria lives in media filter, on plants and ornaments, and glass.

hayleykahnita said:

You can't change too much water - you can do a 100% water change (given your media in the filter isn't left out to dry for long). The beneficial bacteria lives in media filter, on plants and ornaments, and glass.

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Oh thank goodness xD
My filter media wasnt left dry and I have some live plants in the tank as well as two large pieces of drift wood.

From the figures you give it sounds like your tank hasn't finished cycling. By doing a large water change you've just slowed the cycling process down. If you have animals in the tank this is probably a good thing for them.

In a cycled tank I don't believe you should do such large water changes. If you remove the source of ammonia and nitrite the cycle will crash. The bacteria establish themselves at a level set by the amount of nitrite and ammonia available in the water. If you remove all the water the bacteria will have nothing to feed on. Most sources do not recommend a water change greater than 20%.

As your tank isn't cycled a large change isn't a problem.

Okay. Just to be sure I've got this clear. You can change as much water as you like without killing the beneficial bacteria, but if you change too much water you can remove the bacteria's food source? So it's a bit of yes and no here.

The previous poster suggested it was fine to remove 100% of the water. I'm suggesting this isn't a good idea if your tank is cycled because there's a risk you'll crash it.

Have a read of the following articles:

Caudata Culture Articles - Cycling
Caudata Culture Articles - Water Quality
AquariumFish.net - Things Not to Do to Tropical Fish and Goldfish. Information.

"However before you add animals to the aquarium, do a 20% water change to lower the level of the nitrates." Quoted from the cycling link.

What if the nitrates are sky high - surely more than 20% of a water change would need to be done to dilute the nitrates??

Although I'm not sure why one would want a 100% water change with a cycled tank. However OPs question was can you change 100% of you water, I believe you can. Sometimes readings are just too high to risk if there are any animals in there, sometimes 75%+ doesn't cut it and needs to be close to or 100%.

If OP did a 100% water change, the tank still reads ammonia and nitrites so it's not cycled. If there are axolotls or fish in the tank, they would still be providing ammonia source for the tank. And if the tank is going through a fish less cycle, OP should still be dosing the tank with ammonia anyway so either way the beneficial bacteria still have ammonia to consume. Like Mark mentioned above it would slow down the process but I don't believe it would crash it.

I have 3 guys in my tank because I its the only place cold/safe enough in my home. If I take them out I know for a fact my dogs who like to think they are great hunters will find a way to tip anything I put them in and my house is over 80 degrees so I have a chiller attached to keep the water cold.

I dont mind slowing it as long as the water is safe for them. I just have a hard time telling the shades of purple on the nitrite test so I have been taking out huge portions of water every day, but yesterday decided to do another large water change just to make sure and wanted to make sure that was ok since 85% is the most I have I taken out. Usually depending on the tests I'll take out 40%-50% every day.

I just tested it and the nitrite/ammonia is back at .25 again so I am off to change out more water.

Some argue that changing out too much water at once stresses them out since the mineral content can vary in the new water compared to the old water. Then again the advice given to any person who has to keep an axolotl in a small container for short amounts of time is to do 100% changes. My axolotls are in my bathtub now while I get their tanks set up which could take a while. As long as the water is treated and the same temp most axolotls will be happy. Also nitrite tests are kind of hard to tell and it takes about 5 min to get the result in most liquid test kits. After that they tend to darken up even more.


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Boomsloth said:

Some argue that changing out too much water at once stresses them out since the mineral content can vary in the new water compared to the old water. Then again the advice given to any person who has to keep an axolotl in a small container for short amounts of time is to do 100% changes. My axolotls are in my bathtub now while I get their tanks set up which could take a while. As long as the water is treated and the same temp most axolotls will be happy. Also nitrite tests are kind of hard to tell and it takes about 5 min to get the result in most liquid test kits. After that they tend to darken up even more.


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I watch my clock like a hawk after I am done adding the drops on the nitrite tests because I did notice that they do get darker. Even then most of the colors on the nitrite test look so close in color its frustrating. It doesnt help that I have little light to begin with in my house. I add some big frozen jugs of frozen decholrinated water to the tank after every change to get it back down to the right temp and let my chiller take over from there.

I had a bad test kit that had me pulling my hair out in till I took some of my water to aquarium world hear in Houston (they test with the liquid kit not the strips) and found out my water was perfect so maby you're having the same problem have you checked your kit in a bucket of tap water or have 2 kits or like me have a store near by that has a good testing method and can double check your findings ( I like to take a bottle of regular water and heavy concentration of ammonia ext. To make sure they catch it and are not just telling me what I want to hear