Waterchange?

[Callum]

i did a quick search but didnt find anything. my question is why do you do 50% waterchanges in a planted tank? i read that for fish its bad to do more than 30%.

 

[Themuleous]

Yeh Ive done massive (over 50%) water chages in the past wth no apparent affect on the fish.

Sam

 

[plantbrain]

I do no water changes on my non CO2 planted tanks, have not for 11 months now, just add for top off due to evaporation.

Water changes help if you use CO2 since balancing the nutrients from the rapid growth rates is much easier to balance that way.

You dose frequently to prevent anything from running out, then do a large weekly water change to prevent anything from building up.

Simple and effective.

Regards,
Tom Barr

 

[Moose]

I personally don't think that any amount of water change will harm the fish, as long as the filter is mature, and the water is of the same temperature and is dechlorinated.

To ensure the temperature of the water change is the same do you use another heater or do you just let it sit until it gets to room temperature? or do you just add the water slowly?

 

[voo]

Does the bigger water change (50%) stress the fish more than if u did only a 20% change?

 

[Waterloo Kid]

To get the water to the right temp I just mix hot and cold water straight from the tap, add dechlorinator and plonk it in the tank.

Bigger water changes have larger effects on the water chemistry. For instance if your tank is running very high on nitrates and you change 50% of the water, all of a sudden you may have halved the nitrate level (assuming no nitrates in the tap water). This can be as bad for fish as leaving them in high nitrates. Any sudden change can stress fish. Stability is the key and it's this that people try to maintain by doing more smaller water changes. 50% water changes for EI run tanks is for intentionally changing the water chemistry. It's to help prevent buildup of the large amounts of fertilisers used in the EI method. Probably not wise to keep fragile fish in an EI tank.


WK

 

[madcaow]

^^^^ re the hot water from the tap. wont you get all forms of nasties from the pipes etc. like its bad to drink hot water from the tank.

i would add a heater to heat it up personally (if you have a spare) when i didnt i just boiled the kettle and added a little from that.

ive heard (as tom barr pointed out) that is isnt even completely neceasary to do a massive water change. i guess your tanks need to be pretty much spot on tho.

 

[Tolak]

The type of water heating system has much to do with the question of using hot water from the tap or not. If the replacement water is close to that of the tank in regards to pH & hardness, large water changes are no problem, provided the tank hasn't been neglected and nitrates allowed to accumilate beyond safe levels. Neglected tanks need small daily water changes to slowly lower the nitrates to a safe level.

Discus breeders are known for doing large water changes, sometimes on a daily basis. I change 50% to 80% weekly on angel breeding tanks, fry tanks get 50% daily for the first couple of weeks.

 

[Waterloo Kid]

I have a combination boiler which means that it's just like a kettle really. I guess you might have problems if you had a hot water storage system, especially one made from copper as minerals may leach into the water during storage. My system is a heat on demand type and so there's no opportunity for leaching to take place.
Another thing to bear in mind is that when I do a water change I can change anything up to 100 litres of water. That's a lot of boiled kettles!

WK

 

[Qays]

another reason people advise 30% max is because tap water pH varies, and if you do a large water change, the pH change will be dramatic, therefore putting fish into shock.

 

[plantbrain]

It's to help prevent buildup of the large amounts of fertilisers used in the EI method. Probably not wise to keep fragile fish in an EI tank.

WK

Why do you say this?
Having bred Wild and farm Raised Discus to huge sizes, keeping Zerba plecos, Apisto's, numerous teras and rare wild catfish, there is simply zero evidence to even suggest such speculation.

I keep Altum Angels, admittly one of the more fragile fish in FW hobby in planted tanks with 50-60% weekly, sometimes 2x a week water changes.

Why do you think many discus breeders suggest frequent large water changes?

Regards,
Tom Barr

another reason people advise 30% max is because tap water pH varies, and if you do a large water change, the pH change will be dramatic, therefore putting fish into shock.

When I do a large water change, say 80% on a CO2 enriched tank, the pH varies from .5-.8 units in a few minutes.

Folks have been large large water changes on planted fish tanks for many decades without ever a pH relatable issue.

Think about that one for a moment.
How can people do water changes without killing their Altums, gold nuggests, rare cories, dozens of wild sensitive fish?

If you do regular large water changes with tap or a RO/mix etc, then the tank water will be much more like the tap over time.

It's not the pH that's the issue, it's the salts/ions, ionic shock is what kills the fish.

Try doing a large water change with CO2 enriched tank water, say 75%, and then see what the pH change is with tap thereafter.

Next do the same thing without CO2 but raise pH up using baking soda rapidly.
The CO2/tap water test will not do any harm at all to any fish, the baking soda test will.

After many folks doing massive water changes for Discus and plants, nearly a decade +(See ADA mano's tanks as well, he also does massive water changes for similar reasons) and many folks, I think if there was any credence to the pH/senmsntive fish thing, it would have been very wide spread, but we, nor anyone I know has seen such observations.

If you do not do a water change for months, then do one, that can cause issues, but routine mainteance and upkeep helps, not harms. Such folks have far fewer losses in fish/less disease among other benefits.

Regards,
Tom Barr

 

[danski]

i agree large frequent changes may not be as dangerous as once thought..i do large water changes on my co2 enriched tank all the time..over and above the weekly 50%wc..i recently did an 80%wc to rescape and was concerned about ph shock..then did my 50%wc at the end of the week..my fish were more stressed in the bucket than they were in the new water from the change..the water in the buckets was from my tank also..for a while there because i didnt know better, i did 50%wc a couple times a week to try and throw off the algae..but the algae proved smarter than me
anyway after all this i learned that my fish are much more hardy than i thought..glad i didnt find out the hard way though..dan

 

[Callum]

wait if i have co2 in my tank then the ph will be around 7 atm my tap is 7.8 does this mean i have to lower the ph of my tap water or if i do less than 30% waterchanges i will be ok?

 

[Waterloo Kid]

A point well made. I was just under the impression that sudden chemistry changes (as in ferts) were as bad for fish as sudden pH and nitrate level changes. Looks like your experience puts me right on that one!

WK

 

[russellbrooke]

Another thing to mention. If you're keeping fish in a tank, you must change your water at some point. You absolutly cannot leave fish in a tank without changing the water. I don't know the minimum amount of time between water changes, and the mimimum amount, but in my experience weekly water changes of about 25-30% seem to do the job. I like to think of it like opening the window and letting fresh air in, but for the fish, and plants.

If water isn't replaced, the Nitrate levels will just keep building up and up as Nitrate (from what i understand) cannot be broken down by bacteria in your filter media.

Russ