Waterchanges PH swing

EMBX

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Apr 16, 2007
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Hi,

I was wondering, I do the EI dosing with the weekly waterchanges (50%) and after the waterchange the PH goes from 6.6 to 7.1 a 7.2 according to my probe(Tapwater is 7.6) KH is 4degrees. (According to the testkit :rolleyes: )

I did the EI dosing and waterchanges without fish, but will this PH swing not harm the fish if I put them in next week? Stock will be mainly tetra's and some loaches and Cories. Tank is 75 US Gallon.

If so, what is the best route to go? Lesser but more frequent waterchanges? Or must I prepare the tapwater to a more matching PH? If so, how?

Thanks in advance

Evert
 

Tom Barr

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We all do large watwer changes with and without CO2 without issues and have for decades, the pH is not the issue, the KH is.

pH and CO2 can move around, the KH had better not.

Fish can deal with large changes of CO2 levels, which do affect pH, but cannot deal with large changes in say KH, adding a fish from a KH of 1 to 10 will kill them unless done very slowly, and even then.......

pH change is dealing without adding CO2 when it's written about, it leaves out our special case where pH is articifically depressed using CO2 gas.

You can do 90% without any issue as long as the tap 's GH/KH are stable.

Regards,
Tom Barr
 

EMBX

Junior Poster
Apr 16, 2007
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Louisville, KY USA
Thanks Tom,

That is a relief.
One question though, I one time did a 90% big waterchange to get rid of GW, and my harlequins went directly belly up when i poured the water in, Temp was fine, so I really thought it was a PH issue, I had a small 10 gallon next to the 75 and could safe at least a bunch of them to catch them fast and trow them in the 10 gallon but it scared the s*** out of me.

But thanks for clearing this thing up :)

Evert
 

Tom Barr

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KH might have been different than that of the tank, or GH.
I only add maybe 1-2 GH degrees on top of the tap etc.
I never add KH.


Regards,
Tom Barr
 

shane

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Being that ADA AS softens the water, is there any danger in changing 80%+ water?
 

Tom Barr

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Large water changes are fine as long as you do them frequently,. only so much will happen in one week:)

I use Dechlor, Amquel or Prime.

Regards,
Tom Barr
 

EMBX

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Apr 16, 2007
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Yes Shane, I used Amquel. Maybe, the more I think about it, it was a temp issue after all, I poor the water straight from the tap (Cold/warm mixed) and handfeel for the right temp. if I am a degree of it should not matter normally with a 50% WC, but with the 90% WC it probably did matter.

Evert
 

VaughnH

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Jan 24, 2005
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Fish are not so delicate that a change in water temperature due to a water change will kill them. If you ran the tank at 80F and changed 90% of the water to 50F, yes it would kill them. But, being 10F off in temperature should make no difference to the fish, since the change is gradual due to the relatively slow rate of adding the new water. I find my fish love to swim in the colder water as it comes in when I use unheated tap water. So, those fish are getting zapped with a really sudden temp change.