Partial Water Changes. Waste Of Time?

[crazychris]

I've always done regular partial water changes, at least fortnightly, but went to see a lady I know who keeps fish today and she says she hasn't changed any water for 4 months. She has a very good external filter though and I couldn't believe how crystal clear her water looked. She says she got talking to a man in the LFS and he hasn't done a water change for 3 years and doesn't lose fish apart from with old age!! So are we all wasting our time with water changes? Discuss please.

 

[drobbyb]

Not doing waterchanges is asking for trouble. Back in the 70's waterchanging was thought to be harmful. The fish survived through a little luck and a lot of adjusting to the build up of toxins (old tank syndrome). If they were to perform a moderate regular waterchange, their fish would certainly be subjected to shock, and possibly die. Because of this, back then, it was considered foolish to perform waterchanges at all. But in today's world we now scientificailly know that waterchanges are a vital tool at keeping the toxin's low.

If that guy has gone 3 years without a waterchange, I would say that he has been extremely lucky. If he were to start doing waterchanges now, he would draw the conclusion that waterchanges are bad because his fish were negatively affected.

It's just old practices poking their head out. Just as fish-in cycling has fallen by the wayside due to fishless cycling being the preferred method, not changing your water should follow this same path.

 

[crazychris]

Well he was a very old man in his 80's apparently, said he's kept fish 65 years!!! I'm not stopping doing water changes as surely they're beneficial and I enjoy doing them actually.

 

[lilacamy931]

the filter bacteria can only do so much, eventually I would imagine the buildup could get a little much.?

 

[kelly528]

With a heavily planted tank and very, very low stocking, sure. But I'll leave that to the experts!

 

[Inchworm]

I don't ever remember thinking water changes were bad, but years ago we thought more about cleaning the dirt from the bottom with a syphon. Then, clean water was added to fill the tank back up. It's only in recent times that I thought about changing water to reduce nitrates.

When you don't do water changes, and just replace the water that has evaporated, you run the risk of Old Tank Syndrome. It might not effect your old fish for some time, but new fish would be more likely to die as a result.

 

[DiscusKeeper403]

I've always done regular partial water changes, at least fortnightly, but went to see a lady I know who keeps fish today and she says she hasn't changed any water for 4 months. She has a very good external filter though and I couldn't believe how crystal clear her water looked. She says she got talking to a man in the LFS and he hasn't done a water change for 3 years and doesn't lose fish apart from with old age!! So are we all wasting our time with water changes? Discuss please.

Yes, you probably want to do partial water changes. Remember though, many things play a role in how often you need to change water in a fish tank. Tank size and stocking is a big factor, also what and how often you feed. Aquarium plants can help to use nitrogen as a food source and having a good filter always helps. In a healthy tank, all ammonia and nitrites will get converted to nitrates, you can't see any of these (your friend could have much of it, crystal clear water isn't a good indicator.) If these aren't used up by let's say plants, and get higher then 50PPMs you can get into trouble as this is when Nitrates become toxic. Sometimes the build up of nitrogen is slow so the fish adapt and aren't effected (as others mentioned old tank syndrome.) There are self sustaining tanks, that have their own mini ecosystems where all nitrogen is used up, but they are hard to master.

 

[Bignose]

The nitrate at 50 ppm being dangerous is kind of a myth. There is good research in the literature that shows that concentrations up to 1000 ppm show little or no effect for at least some species. I have no doubt that it is species dependent.

The real worry about long-neglected tanks is that the end product of the cycling process, nitrate, is an acid. And the acid will slowly consume your buffer and then your pH will drop as time goes on. Now, the fish can and usually will adjust to the pH as it falls, but it can get low enough to cause problems.

As mentioned above, the real issue will present itself if the long-neglected tank does suddenly get a large water change. The change in the water's hardness (which would usually be no hardness since it was consumed by the acids from the nitrate) can cause what is usually attributed to "pH shock".

There are also necessary micronutrients that are replenished with water changes, as well as removing the levels of micro pollutants. Things that build up over time (like cigarette smoke, carpet fumes, cleaning supply fumes, cooking oil, etc.) -- basically anything that gets in the air gets in the tank to at least some level. Low levels for short times are mostly harmless, but I don't think that leaving most of that in the tank for a long time is a good idea.

Ultimately, I feel that fish can survive in tanks that are neglected, but very rarely do fish actually thrive. And my personal goal (and I suspect most of the forums members' goal as well) is to have the fish thrive to the fullest extent possible.

 

[DiscusKeeper403]

The nitrate at 50 ppm being dangerous is kind of a myth. There is good research in the literature that shows that concentrations up to 1000 ppm show little or no effect for at least some species. I have no doubt that it is species dependent.

The real worry about long-neglected tanks is that the end product of the cycling process, nitrate, is an acid. And the acid will slowly consume your buffer and then your pH will drop as time goes on. Now, the fish can and usually will adjust to the pH as it falls, but it can get low enough to cause problems.

As mentioned above, the real issue will present itself if the long-neglected tank does suddenly get a large water change. The change in the water's hardness (which would usually be no hardness since it was consumed by the acids from the nitrate) can cause what is usually attributed to "pH shock".

There are also necessary micronutrients that are replenished with water changes, as well as removing the levels of micro pollutants. Things that build up over time (like cigarette smoke, carpet fumes, cleaning supply fumes, cooking oil, etc.) -- basically anything that gets in the air gets in the tank to at least some level. Low levels for short times are mostly harmless, but I don't think that leaving most of that in the tank for a long time is a good idea.

Ultimately, I feel that fish can survive in tanks that are neglected, but very rarely do fish actually thrive. And my personal goal (and I suspect most of the forums members' goal as well) is to have the fish thrive to the fullest extent possible.

Very interesting. I am glad you scared this. All your posts are very precise, educated and well informed, you must be a scientist or something?

 

[raptorrex]

And my personal goal (and I suspect most of the forums members' goal as well) is to have the fish thrive to the fullest extent possible.

too me, this is the nub! aslo, my, fish seem to love the influx of new water.