Maximum Water Change

[ThievingScouser]

What would you consider the maximum % water change?

It's an emergency situation (I think a toxin has entered the tank somehow - see my post in emergency section for background if interested) so there's that to consider too.

I read someone somewhere saying they regularly drain it till there's just enough to keep the fish wet!
I've done a series of changes in the last 24 hrs that equate to almost a 75% water swap from original.

Fish are still dying and looking unhappy so I'm getting tempted to do a massive water change tomorrow. Get that 'trouble water' percentage down into the single digits.
The gravels been deeply vacuumed so I'm not worried by adding water disturbing hidden nasties, and the nitrifying/de-nitrifying bacteria lives on solid surfaces right?
So the water itself is to support the fish solely? Provide warmth and oxygen etc.... provided the pH of the new water is the same, can anyone point out any pitfalls to doing a drastic change?

Many thanks in advance.
(of course the damage could have been done to the fish and I'm just going through the motions)

 

[Tolak]

As long as the water parameters are the same or nearly so the only harm from a large water change might be dumping a large bucket of water into a tank with very little water too quickly, creating excessive turbulence.

I'll check out your other topic.

 

[ThievingScouser]

I'll check out your other topic.

Thanks

Sorry, forgot to mention, the "2 Deaths" thread starts with an issue I had a couple of weeks ago.
The recent problem starts on post #7 (although one does follow the other)

 

[ThievingScouser]

As long as the water parameters are the same or nearly so the only harm from a large water change might be dumping a large bucket of water into a tank with very little water too quickly, creating excessive turbulence.

Great, that's what I'd hoped.

I'm pretty new to the hobby, so am glad someone more experienced could confirm what I've understood from reading around.

Thanks
Ed

 

[-SPB-]

I've done an 80% change a couple of weeks ago without any ill effects, this was because I had to change meds I was putting in the tank.

 

[rewlyn]

im currently doing a fish-in cycle and ive pushed limits

80% w/c is fine just set up your bucket with all products you use ie: dechlorinater etc.

once you done that se if you can syphon it in to stop turbulance

and is the bucket temp the same as tank cause i know they can handle going from 80f to 70f with out any hassles

good luck

 

[ThievingScouser]

Something just occurred to me. The "rinse your bio-filter in tank water" thing. Is that strictly necessary? Could it be rinsed in RO or treated tap water?

A huge water change would be taking 80-90% new water into the filter, effectively rinsing the bio-media in non-tank water.

 

[ThievingScouser]

Cool, it's sounding like an 80% change is on the cards for tomorrow morning (will take a while, that's 240l to bucket back and forth )

Think I might be "feeling unwell and unable to get into the office" tomorrow morning..... it's in a good cause!

 

[Tolak]

As long as the water is dechlorinated it will work. This can be old tank water, dechlorinated tap water, ro water, or even well water that has no disinfectants added. You can get away with giving mature media a quick rinse in untreated tap water, this is not something you would want to do with newly cycled media, or without some sort of backup measures.

 

[-SPB-]

Cool, it's sounding like an 80% change is on the cards for tomorrow morning (will take a while, that's 240l to bucket back and forth )

Think I might be "feeling unwell and unable to get into the office" tomorrow morning..... it's in a good cause!

I like the thinking, getting the priorities right lol!!!!

My tanks roughly 340l and with a 15l bucket took a very very long time to do an 80% water change. I was glad when it was done!!

 

[JenCliBee]

As people have commented, no volume of water change are actually harmful if done right , i regulary change 100% on certain tanks(most are plec tanks) and never had any adverse effects nor any ill fish

jen

 

[rewlyn]

IF YOU HAVE A GRAVEL SYPHON YOU CAN SAVE TIME BY EXTENDING THE LENGTH OF YOU OUTLET HOSE BY CONNECTING A GARDEN HOSE TO IT,
THIS WILL ALLOW YOU TO RUN IT IT DIRECTLY OUTSIDE WHEN EMPTYING, YOU CAN ALSO REVERSE THE PROCESS FROM YOUR TAP TO YOUR TANK MAKING SURE YOU ADD THE DECHLORINATER DIRECTLY IN TO YOUR TANK FIRST, THIS WILL NUETRALIZE AS IT ENTERS THE WATER.

THEN YOU HAVE NO BUCKETS T DEAL WITH

 

[snowflake311]

I have done an 80% water change a few times. It is safe to do large water changes every now and them. Sometimes you have to. If you do a 80% water change everyday Then you might have problems with messing up your Biological filter. I don't know why so many people think you can not take out any more then 25% at a time. That's just silly. Your tank will be fine and I am sure you fish will be happy with the fresh water.

 

[ThievingScouser]

I took out as much as I dared, any more and some of the fish couldn't have stayed upright!

Couple of hours later and sore hands from lugging 20kg buckets with narrow handles and fish are looking MUCH happier.
I lost count part way through so was either 240 or 260l. Seems to have made a good difference anyway.

Will keep a close eye on test readings for the next week just incase the bio-filters taken a knock.