Can you over waterchange?

[Tropical Tony]

Hi guys. Had my 150l tank for nearly 2 months now and I do water changes twice a week and take between 30-40% out each time. I was just wondering if you can over waterchange tanks?

 

[Derekshatch]

Not realley unless if you get rid of all of the beneficial bacteria. Also you dont want to scare the fish by doing water changes to much.

 

[PheonixKingZ]

I agree. I can't imagine it being bad for your fish. (I take that back, it may cause stress)

 

[Byron]

The quick answer to your question in post #1 is no. You can never really change too much water, provided the tank is biologically stable and the water parameters are reasonably close.

The problem is in tanks where things have not been maintained. For example, if organics increase as will happen if water changes are not regular and substantial, such as when one goes away for a week or two, or if the tank is overstocked (or inappropriately stocked) which means it is not biologically balanced to begin with; insuch cases neglect may cause the pH to lower drastically, to below 7. Ammonia in acidic water is ammonium which is basically harmless to fish. A substantial water change using basic pH (above 7) water will cause the pH in the tank to rise above 7 and the ammonium immediately changes to toxic ammonia, likely killing the fish. But this is the exception, and proper maintenance will not get one into this situation.

Doing two 30-40% changes is good, but if you did one 70-80% change it would be considerably better. The more volume you change the better. For instance, one weekly 70% change is much more effective and beneficial than daily 10% changes, yet the same volume is changed per week. The less water changed at one time, the more pollution is left behind, and it simply keeps increasing.

Fish never get sick from clean water. If one wanted to do a 90% water change every day it would benefit the fish. Discus breeeders do this in their fry tanks, often changing 90-95% not just once but even twice daily. The fish grow faster and are healthier. This applies across the board, provided the parameters are within reason and it is regular. This is the key to a stable biological system. Most of us find once a week adequate, provided it is significant.

Water changes have no detrimental impact on any beneficial bacteria; these live on surfaces not in the water.

Edit. Stress from the water change was mentioned...the stress fish live with when water is not sufficiently changed is far more significant. And many of us find that the fish seem little bothered. I have had small fish swimming around my arm when it is in the tank with the Python, and other members have mentioned similar experiences.

 

[FishGuest5123]

The quick answer to your question in post #1 is no. You can never really change too much water, provided the tank is biologically stable and the water parameters are reasonably close.

The problem is in tanks where things have not been maintained. For example, if organics increase as will happen if water changes are not regular and substantial, such as when one goes away for a week or two, or if the tank is overstocked (or inappropriately stocked) which means it is not biologically balanced to begin with; insuch cases neglect may cause the pH to lower drastically, to below 7. Ammonia in acidic water is ammonium which is basically harmless to fish. A substantial water change using basic pH (above 7) water will cause the pH in the tank to rise above 7 and the ammonium immediately changes to toxic ammonia, likely killing the fish. But this is the exception, and proper maintenance will not get one into this situation.

Doing two 30-40% changes is good, but if you did one 70-80% change it would be considerably better. The more volume you change the better. For instance, one weekly 70% change is much more effective and beneficial than daily 10% changes, yet the same volume is changed per week. The less water changed at one time, the more pollution is left behind, and it simply keeps increasing.

Fish never get sick from clean water. If one wanted to do a 90% water change every day it would benefit the fish. Discus breeeders do this in their fry tanks, often changing 90-95% not just once but even twice daily. The fish grow faster and are healthier. This applies across the board, provided the parameters are within reason and it is regular. This is the key to a stable biological system. Most of us find once a week adequate, provided it is significant.

I agree with Byron by so glad I didn’t have to type all of that.

 

[Tropical Tony]

Thanks for the replies guys! Think I’ll start foing weekly 50% waterchanges from now on

 

[Lajos_Detari]

If you look at the fish in the big rivers like Amazon, Orinoco, the water keeps changing...
I think this is the best condition for the fish.

But since we can't do water changes everyday like the fish breeders as it will take too much work.
Then as Byron suggested, perform large water change once a week will be good.
I do 90+ % of water changes twice a week.
My smaller fish will come swimming around my siphon and hose whenever I change water.

 

[Colin_T]

Just make sure any new water is free of chlorine/ chloramine before it is added to the tank.