Water changing how much how often

[FJB]

People would argue all across the spectrum...
The way I see it is - For the overwhelming majority of fish, water exchange (the volume of water they are contained in at a given time, and its rate of exchange with surrounding water) is much, much higher than what we offer in tanks. More so for riverine species but even for many lacustrine species. In addition, natural communities have infinitely more extensive buffering systems that provide a much higher stability than typical aquaria.
Therefore, in my tanks, the 60-70% weekly water change I do is much, much less, so I should strive to accomplish it every week, and more if I can.
The general philosophies of striving to do the least water changes in tanks, and that of "seeing how few or small water change I can get away with" are bent.
The experiments of what one can do with closed systems and all of that are very nice, but that is only what is all about for very few fish keepers.

 

[FahakaPapa]

There are so many ways to look at it. I think of my puffer in the wild... looking for food non-stop, probably going hungry a lot of the time. In my tank.. she's grown to 11.5 years old and looks better than ever. Never hungry, unless I think she needs a little bit of a fast (I'll take a whole week off from feeding at times). By "never hungry", I mean she is well fed, but she's a puffer, so she's always "hungry". That being said... I still like doing large water changes/week, but it's not my puffer that I'm worried about - it's the phosphates/algae. If I don't do that water change, my phosphates start building up and the algae follows suit (nitrates stay under 10ppm from one WC to the next). My tap water sits at about 1.0 ppm of phosphates. So it's high from the start. I could use some sort of phosphate removers, etc., but I feel that the water changes are best to ensure it doesn't build up. My puffer definitely enjoys it too. Always swimming in the new stream of water being added to the tank (even though it's always cold lol). Sometimes I match the temp by touch, but most of the time I just keep my tap full blast cold.

 

[TwoTankAmin]

I have been at this for just over two decades. The one thing I can say with 100% certainty is that, to date, I have never read, never been told by another keeper or mentioned at any fish related presentation that a fish died or got sick because their water was too "clean."

I change 50% - 60% weekly on all tanks. however, I have lovely well water which doesn't need to be treated and I can fill tamks at temp right from my tap, However, the water comes out with excess co2 in it that I outgas and also oxygenate by going from tap to Rubbermaid cans and then I pumpto tanks from there. Because garden hoses often come with mold inhibitors, I switched to drinking water caliber hoses for refilling.

 

[midasman714]

My ideal routine is 15-20% every three days (including vac), so roughly 40%/6 days. This is based on visually observing the fish after the change.

If I do 50%/week the fish seem to behave the same, I just prefer smaller more frequent changes.

I did try 85% recently and I did notice some stress afterwards.

Like others have said, lots of factors, everyone's situation is different, try a few variations and see what works for you.

 

[2Itiwhetu]

It is about balance, but I would suggest that really large water changes over 75% could actually be detrimental to your fishes health and that you should just consider why you are doing such large water changes.

 

[esoxlucius]

It is about balance, but I would suggest that really large water changes over 75% could actually be detrimental to your fishes health and that you should just consider why you are doing such large water changes.

I've always carried out fin level water changes, typically 80-90%. I'd rather do it that way than multiple piddly 25-30% changes every day or two.

The key with very large water changes, for me, is never ever forget to add dechlorinator, observe the fish, and just hope that the local water company hasn't "fiddled" about with your water.

In my case, my water supply is extremely consistent year round, I never ever forget to add dechlorinator and as a result I no longer have the need to sit there studying my fish as the tank refills.

Water changes are not a one size fits all situation.

 

[skjl47]

Hello; Some good ideas already. Guess the thing is you can do frequent and large % WC and not be wrong in terms of water conditions for most anyone. Might become a big chore to do and might cost some money for the water. The idea being even the largest tank setups rarely approach a natural habitat in terms of volume and water turnover.
The problems come from trying to get by with smaller % and less frequent WC. Using parameters is a sound way to judge.

I will add two things. I would not go from 25% WC once a week to 90% every two days all at once. I would build up over several WC. Say 30% every two or three days for a bit. Then 40% every two days for a couple of WC. Then 60% every other day and finally 90% every other day. This schedule is not important in itself, the idea is to not shock the fish with drastic water parameter changes all at one time.
The other thing is to stay ahead of evaporation. Say if in a week your tank losses an inch of water from evaporation, then the WC needs to beat least twice or greater than that amount of water. If one inch is two gallons, then the absolute minimum for a WC needs to be some multiple of two gallons. If you were to top off a tank only, then over time the minerals and other such things will build up concentrations. Of course nitrates will get too high long before in most cases.

Good luck

 

[TwoTankAmin]

If one follows the idea that, unless one is dealing with a real problem than needed immediate action, water changes cannot be too big or too frequent. What I mean by this is if one can know the the new water going in fairly closely matches what came out, how can too much water being changed be harmful to the fish?

I do know that water changes are a somewhat stressful experience for some fishm but not fo them all. I am also not certain how much stress a big water change causes. My experience on this front has formed my opinion on this. A good example would be my now gone 50 gal. high tech planted tank, It contained a number of SAES. When the tank was fairly new and I would do weekly maint. and wcs, the fish would pretty much all hide, As time passed fewer of them did so and those that did, did so more "calmly."

But the most amazing part of this was that when I had my arm in the tank to do something I would feel what felt like a barber's eclectic trimmer on the back of my hand. it was an SAE trying to nibble the "hair algae" off of the back of my hand. The fish did not know he was trying to eat real hair. I had sever4al SAE try this.I can tell you it tickles. I can also tell you those tiny amano shrimp claws actually feel like a tiny pin prick, It is painful you enough that you feel it bu not bad enough that it really bothers you.

The point is I believe fish adapt to their specific situations the best they can. While they may not have great brain power many do seem to learn. And with that learning can come stress reduction., This is one of the reasons why I dislike fish in cycles. Most people do know understand Total ammonia being in twwo forms and that the same level of ammonia in one tank can be safe for a but while that same level in another tank is fatal. That leads to the mistaken advice that if one has any level of ammonia in a tank they must immediately do a water change. But the tank is new, the fish are new and the stress from multiiple water changes in a short period of time is most certainly greater than it will be down the road. If some such changes are not really needed, I believe they may do as much or more harm as good. They and slow down the cycle.

I do not believe big water changes are harmful if the water going in is "good" and the tank is mature and the inhabitants have been there for a while,

If you have never seen this, you may find it interesting.

Compare that to how Discus Hans does it in his facility Discus hand Water Changing

Talk about two completely different methods..........

 

[The Masked Shadow]

50-60% weekly.

 

[robmcd]

I do 50%, once a week on my big tank. I did just give away 5 medium to large cichlids that were housed in there, so I imagine that the bioload will go down significantly, but I will still stick to 50% a week.

On my smaller, C02 injected planted tank, I do 40% twice a week. Only because I am lightly dosing the new water with ferts and Excel.