Too much of a water change?

[GrapeGuy]

I do a 50% water change every week. Is that overkill because I hear other people doing 20% water changes for african cichlids.

 

[xraycer]

I do a 50% water change every week. Is that overkill because I hear other people doing 20% water changes for african cichlids.

Not at all! I do about 70% twice a week for all my tanks. Been doing this for the past 5 years.
20% once a week is absolutely useless!

 

[BichirKing]

every tank is different. different water conditions out of the tap, different bio loads, feeding, filter maintenance (or lack thereof). the only true way to know what your tanks requirements are is to test your water before and after water changes. keep a log for a few weeks to month of daily water tests. you will be able to see the cycle. when you do water changes that are to small you'll see that too. stick to a regular feeding schedule and amount of food. a good example is my 240 that's mildly stocked that's right next to my 125g that is lightly stocked. the 240 gets about 2/3 maybe a little more of the water changed every 4 days. the 125 can go about twice that long with roughly a 50% water change. but I also clean my filters (mechanical) alternately every week.

 

[LBDave]

I agree with John (each tank is different), but I don't think you can overdo water changes. The more the better. If you follow Duanes comments he changes every 2 or 3 days. And he doesn't overstock the tanks. Once a week may do, but better to do twice IMHO.

 

[GrapeGuy]

Thanks now I understand. I was worried it might change the water parameters too severely, thus harming the fish.

 

[xraycer]

every tank is different. different water conditions out of the tap, different bio loads, feeding, filter maintenance (or lack thereof). the only true way to know what your tanks requirements are is to test your water before and after water changes. keep a log for a few weeks to month of daily water tests. you will be able to see the cycle. when you do water changes that are to small you'll see that too. stick to a regular feeding schedule and amount of food. a good example is my 240 that's mildly stocked that's right next to my 125g that is lightly stocked. the 240 gets about 2/3 maybe a little more of the water changed every 4 days. the 125 can go about twice that long with roughly a 50% water change. but I also clean my filters (mechanical) alternately every week.

This is true, but there are no readily available tests for this such as growth retardant hormones and who knows what else that lurks at the molecular level that we yet to know about. As far as I'm concern, the more frequent, and the bigger the water change, the better. Regardless of how pristine one thinks their tank water is.
Breeders in Southeast Asia are known to do 100% wc daily.

 

[LBDave]

If you do 50% you should be fine. I know africans prefer a little higher ph. Do you know your tap water ph? Do you monitor ph?

 

[xraycer]

Thanks now I understand. I was worried it might change the water parameters too severely, thus harming the fish.

There are people who will advise not to do wc because when they did, fish started dying. They don't understand that doing a significant wc once a month or 2 is disastrous.

 

[BichirKing]

This is true, but there are no readily available tests for this such as growth retardant hormones and who knows what else that lurks at the molecular level that we yet to know about. As far as I'm concern, the more frequent, and the bigger the water change, the better. Regardless of how pristine one thinks their tank water is.
Breeders in Southeast Asia are known to do 100% wc daily.

hormones I read can be removed with carbon. not sure if its true but I run it in my Bichir tank for that reason. also if I could change 100% everyday i'd do it.

 

[duanes]

In aquariums we normally stress the nitrogen cycle, and that is because it is about the only cycle, we as aquarists can easily control, with bio media nd its biofilm of beneficial bacteria.
In nature there is also the phosphorus cycle, the sulfer cycle, photosynthesis and many more cycles at work that contribute to the exchange and cleaning water in any non-polluted system.
There are also myriads of micro to macro animals that help break down organics pollutants we really don't normally have access to.
Add to that the constant movement of rivers, rain, flow in aquifers that constantly put fish in perpetual water change.
The Amazon river flow over 12 million cubic kilometers of water every minute ("1" cubic meters is about 250+ gallons).
So to me, the idea that any aquarist can do of too much a water change borders on the ridiculous.
As LBDave said above, I try to do 30%-40% ( a pittance) every other day, based on pH, alkalinity and nitrate trends after years of testing my tanks. If I test tank water, and nitrate readings are above 5ppm, I do a large water change.
5 ppm nitrate, or a sudden drop in pH of 2 ,or alkalinity of 20ppm being my high/low end indicator points.
I have done nitrate tests daily on raw Lake Michigan waters when I worked as a chemist for a large drinking water facility, and I have been testing natural waters here in Panama lately, I have yet to find detectable nitrates here, or way back when, in Lake Michigan.