water changes

[JDC]

If the water tests okay, do I still need to do partial water changes.
55gal tank, not too crowded

 

[Torrean]

I've wondered this myself. Water changes are used to remove Nitrate from the water right. Well if I have plants and they absorb the nitrates then do I still have to do a water change. I believe the answer is yes. First of all you need to clean your gravel anyway. Second I have heard that not doing water changes can cause small critters such as ich to build up to a saturation point causing an infection in your fish. I had a couple more reasons but they seem to have slipped from my mind. Sorry, I'm sure you'll get more replies on this one though.

It may do well in the begginer's forum.

 

[rdd1952]

I think the main reason that we ever do water changes is to vacuum waste and just replace with clean water. After the tank is cycled, you shouldn't ever have ammonia or nitrite and the nitrates should stay in check either because the plants use them or algae uses them. You do need to vacuum the gravel/sand and remove the waste of left over particles of food or dead leaves.. Water changes don't have to be large, maybe 10%, just what comes out during the vacuuming.

 

[FrAnK3333]

As stated above its for waste removal, but most of all its to put fresh water into the tank.

 

[vantgE]

There are other toxins present then would normally be tested for do regular watter changes

 

[freddyk]

Franks right too. Changing water is also to re-introduce nutrients into the water that have been used up by the livestock.

 

[Fiori]

Apart from the idea that fresh oxygenated water would be welcomed by the fish, I believe that there are minerals and trace elements that are used up in old water and this can cause a GH drop if left too long.

 

[ncjharris]

Bear in mind that in the wild, the fish will live in a body of water that is open to the water cycle, whereas our tanks are closed.

Water changes are needed to carry out what rain, evaporation, perculation and the like do.

 

[CFC]

Fiori is on the right track

Apart from the idea that fresh oxygenated water would be welcomed by the fish, I believe that there are minerals and trace elements that are used up in old water and this can cause a GH drop if left too long.

One of the biggest reasons we do water changes is to replace the buffering elements which make up the KH that need to be present in the water to prevent the pH from crashing.
By the very nature of the nitrogen cycle calcium buffers in the KH are used up by acidic organic compounds which are released as organic matter breaks down, this is also aided by CO2 released by fish breathing and to a lesser extent by plants which release CO2 during hours of darkness. If left to a stage where all the calcium buffers in the tank are used up (how long this takes depends on the bioload of the tank, the KH of the original water, the effectiveness of the filtration system and many other factors) then the pH of the water becomes very unstable and crashes to fatally acidic levels, this is sometimes known as OLD TANK SYNDROME, it is not unusual to find that a old neglected tank can have a pH of 4 or less!!
So even if your tank is lightly stocked, heavily planted and you have never seen a trace of nitrate in the tank you still have to do water changes at least once a month to ensure that your tank remains a healthy stable enviroment for your fish to live in.

 

[Bignose]

I think CFC did a fine job saying why new water has to go in -- old water should come out as well to remove all the trace chemcials -- like cooking oils and paint fumes and carpet fumes and cigarette smoke and cleaning chemicals and all the other stuff that gets into the air. Small amounts of these will get into your tank as well. By doing water changes, you take at least some of these pollutants out, and keep them at very low levels. If you neglect water changes, there is the possibility that the levels of these things, low they may be, may become dangerous not to mention long-term exposure to pollutants can have a negative effect as well.