75% water changes

[kwi]

You're fortunate to have a chlorine free water source, most of us need a dechlorinator/conditioner as a minimum. (In fact that is the only chemicals I've seen recomended to be added to water.) And I've been advised here to select fish that suit my water rather than adjusting my water, which makes sense, to me at least.

 

[itiwhetu]

You're fortunate to have a chlorine free water source, most of us need a dechlorinator/conditioner as a minimum. (In fact that is the only chemicals I've seen recomended to be added to water.) And I've been advised here to select fish that suit my water rather than adjusting my water, which makes sense, to me at least.

Most of the town supply in NZ has chlorine in the water. I have until recently had to deal with that. Here the chlorine sits in the water as an inert gas, that is why the smell disappears quickly. If you use a hose nozzle to fill a bucket most of the chlorine has gone immediately. Then if you only do a 25% water change the rest is not going to effect the fish and will dissipate very quickly. You can naturally buffer your tank with the like of peat or limestone etc so you can make your tank fit the fish you are keeping.

 

[kwi]

Our local water has Chloramine which doesn't degass the way chlorine does and needs removed. Check that your water companiy definitely doesn't use chloramine, it's cheaper.

 

[Byron]

I started this discussion because I was told that 25% water changes was old school and the new way of doing things is to do 75% changes and keep the water as close to source as possible. That is fine but then we have a member with a fighting fish in water with ph 8 and is being told to do large water changes with water that has a ph of 8.5. How is this good for the fish.

The issue is not as straightforward as this. An aquarium is biologically a closed system even though there is some exchange of gasses at the surface. At the same time, every process that occurs in the aquarium is subject to and will follow the natural laws involving biology, chemistry, microbiology, etc. Every chemical substance we add to the water will impact these processes for good or bad (usually the latter). As fish live, the water becomes polluted, and this does not stop unless we do a water change. No amount of filtration can remove pollutants; filters remove or more correctly capture solid waste but it breaks down into liquid and stays in the system. The water continues to deteriorate 24/7. The more fish, or the larger the fish, or the more they are fed, or the more inappropriate the combination of species are--all of this increases the pollution. Live plants do help, but with the fish load most of us have, this will never be sufficient.

Changing out a substantial portion of the water for fresh water on a regular schedule is crucial to a healthy aquarium and healthy fish. Provided the parameters are reasonably close, the more water changed and the more often, the better. But few of us want to be doing water changes like some discus breeders do--90% of the tank water changed two or three times each day in fry tanks. The fact that fry grow faster and develop better health in such conditions is absolute proof there is clearly a benefit in water changes.

I do 60-75%, maybe even 80%, once each week. My tap water is zero GH/KH, as are the tanks, so this is ideal. The pH does fluctuate, but this is less significant. Some of my tanks are below 5 in pH. My tap water is 7, achieved because they add soda ash to the water supply to raise the pH. This dissipates out within a matter of hours, and the stable biological system of the aquarium means the effect is minimal. Provided the GH is close, and the temperature is close, the pH is less of a concern.

 

[itiwhetu]

Under the system I have been working on one of the key points is that 30-50% of the volume of the tank is in plants, with that level of plants working as a biological filtration system, the tanks remain remarkably stable, with only 25% water changes once a week

 

[AdoraBelle Dearheart]

Under the system I have been working on one of the key points is that 30-50% of the volume of the tank is in plants, with that level of plants working as a biological filtration system, the tanks remain remarkably stable, with only 25% water changes once a week

Not doubting you or saying you're wrong, just trying to find out more, but stable in what sense? Do you test for nitrates, pH etc over time?

 

[Byron]

Under the system I have been working on one of the key points is that 30-50% of the volume of the tank is in plants, with that level of plants working as a biological filtration system, the tanks remain remarkably stable, with only 25% water changes once a week

I would suggest that if you increased the volume of the weekly PWC to 50-70% you would have a more stable and healthier system. Mention is not made of the number of fish, nor the species, and then of the tank volume, nor of the plant species--but there is no way that the plants could override the benefit of more substantial water changes. For one thing, plants cannot remove most of the actual "pollution" that accumulates 24/7.

Water pollution involves what the fish are removing from the water as well as what they are adding, and what the plants are removing from the water. We can have a well planted tank that will have zero ammonia and nitrite, and nitrate might even be close to if not zero...but the water is still being significantly polluted every day. Fish release chemicals such as pheromones and allomones, and plants cannot touch these, only removal via a water change can reduce them. Fish are altering the chemistry of the water through their life processes in ways that plants cannot even impact.

We may think that things are stable if the ammonia/nitrite/nitrate do not change, and if the pH never fluctuates from week to week. This is certainly the goal, but it is only the aspect of biological stability that we can measure. There are the unseen and unmeasurable pollutants. The more water changed, the less there will be of these pollutants.

 

[itiwhetu]

Not doubting you or saying you're wrong, just trying to find out more, but stable in what sense? Do you test for nitrates, pH etc over time?

Stable in the fact that hardness and ph remain constant and that the system has o ammonia levels. If you use a specific natural base medium for a tank and never disturb it the roots of the plants will keep it clean and the base will consistently leech minerals into the tank, keeping it stable

 

[seangee]

There really is no right or wrong answer. The key is stability and sustainability over time. And its not just about nitrates or pH.
@itiwhetu you are absolutely right about plants, and of course stock levels play a big part too. Many would regard my tanks as overstocked (and I'm ok with that).
But so many people in the hobby's first question is how many fish can I keep in a xxG tank?, often with reference to silly things they have read or heard. We also get the I have fake plants because real ones are too hard, or the yes my tank is planted, I have 2 moss balls and an anubias. And of course the man at the fish shop said I should change 10% once a month.

So as a starting point I always recommend 50-75% to everyone. 75% happens to be what I do in my own tanks. But I also know that when I leave them to go away for 3 or 4 weeks they come to no harm. And on an even more practical note, the vast majority of problems posted on this site are resolved by doing larger and more frequent water changes.

Love your signature line BTW. Also agree wholeheartedly with @Byron's

 

[PheonixKingZ]

This thread has been a very interesting read, because I have been wondering this myself. Thanks everyone for the great advice!

 

[AbbeysDad]

Regular Partial Water Changes
Partial Water Changes
Bacteria in the FW Aquarium

 

[CassCats]

My weekly water change in my 55

Fish think its Armageddon for maybe 5 minutes then get all excited because they know fresh water is coming in, the cories parade around the tank in a huge pack.

You cannot have too much fresh water

 

[HoldenOn]

My weekly water change in my 55
View attachment 117211
Fish think its Armageddon for maybe 5 minutes then get all excited because they know fresh water is coming in, the cories parade around the tank in a huge pack.

You cannot have too much fresh water

Mine do that too Its cute to see them bustle around.

 

[AbbeysDad]

You cannot have too much fresh water

Generally very TRUE....However, one exception: If a tank has been neglected for some period as to promote what's commonly referred to as 'old tank syndrome' a large partial water change can cause such a dramatic change in water chemistry as to shock and stress the fish. In some cases, this could be fatal.
In such cases, it's best to do several small water changes a day at a time until the water reaches a point where larger volume changes are fine.

 

[BumblePrime]

I'd also add that hormones are something that fish release and in certain species like discus fish and accumilation of hormones can actively stunt and misshape the species. I change over 100% a week via two large water changes.