Water Change and Shrimp Activity

brbarkey · Post by **brbarkey** » Wed Oct 27, 2004 4:47 am

When I change my water (about 20 gallons) in my 75 gallon tank I notice that a lot of my shrimp start swimming around and are a lot more active. The 75 gallon tank has a kH of 5 and gH of 6 pH is 6.8. The water that I put into my tank is R.O. water that is rebuilt to gH 8, kH 6 and the ph 8.0. Is the difference in ph swing effecting my shirmp and stressing them out?

let me know what everyone thinks

below is a link to a picture of my tank

brbhttp://aquabotanicwetthumb.infopop.cc/e ... =196107938

Bradimus · Post by **Bradimus** » Wed Oct 27, 2004 6:23 am

Water changes usually spark a shrimp parade in my tanks. I am not sure if it is stress, especially if the temperature is about the same. Water changes often spark spawing behavior in fish.

Aphyosemion · Post by **Aphyosemion** » Wed Oct 27, 2004 11:30 am

Anytime you make a sudden change in PH of more than .5, it stresses your fish and I'm sure your shrimp, as well. You are making a PH swing of possibly as much as 1.2, so I wouldn't be surprised if that was it. Water temperature can be another thing that will compound the stress if the temps aren't close enough. In the case of a 20% water change on a 75 gallon tank, the difference would be considerably diluted though. As long as they aren't doing acrobatics like swimming and hanging around upside down, I wouldn't lose too much sleep over it, but I would try to get those water parameters a little closer.

-Aphyosemion

amanda_h · Post by **amanda_h** » Wed Oct 27, 2004 11:35 am

It makes sense that the ph fluctuation would be stressing them, but that doesn't explain why my fish all seem to congregate where the fresh water is coming in. Wouldn't they be running away from it?

The shrimp do it too. They zip around the tank, but they also will land on and hang out around the python hose when I add water.

Weirdos.

filishy · Post by **filishy** » Wed Oct 27, 2004 1:01 pm

Mine also get very active afterwards, not during. However, in my case, both temp and pH is about the same.

I love to do water changes because of the activity that I get to see right after one.

Bradimus · Post by **Bradimus** » Wed Oct 27, 2004 2:42 pm

Aphyosemion wrote:Anytime you make a sudden change in PH of more than .5, it stresses your fish and I'm sure your shrimp, as well.

Do you have a citation for this? I have seen it stated often, but have not seen a formal study of it.

51Cornell · Post by **51Cornell** » Wed Oct 27, 2004 7:41 pm

IMHO, I always kind of figured water changes are kind of like "rain" bringing in new fresh water to the aquatic lifeforms.

Aphyosemion · Post by **Aphyosemion** » Thu Oct 28, 2004 7:38 am

In the case of the .5 rule, I have not only read it on PH altering products, but read it in Tropical Fish Hobbyist magazine a few times. One article went into the an explaination of the exponential difference in a .1 PH difference and a 1 point PH difference. It isn't addition, but multiplication. I would quote the specific article, but I get rid of my old magazines to keep them from piling up.
Anyway, who said it is not as important as the theory behind the rule. Large PH swings are bad, so keep them to a minimum is what is trying to be articulated.
In the case of the 75 gallon tank with a relatively small water change, the increased activity might just be a product of new water and excited shrimp.
-Aphyosemion

beviking · Post by **beviking** » Thu Oct 28, 2004 10:53 am

Maybe this will shed some light on pH...
http://www.rhtubs.com/pH.htm

Short answer, each 1 point change in pH equals a ten fold change in acidity/alkalinity.

As for the water changes...
I agree with the fresh water idea. Biological by-products accumulate constantly and the fresh water must be like a breath of fresh air to them. At least that's how I see it.

Bradimus · Post by **Bradimus** » Thu Oct 28, 2004 1:51 pm

I am quite familiar with the logarithmic nature of the pH scale. However, this does not offer any explanation as to why a change of 0.5 stresses animals. In fact, the logarithmic nature of scale suggests that any guideline like that is flawed.

I have read various rules as to what size of pH swings affect animals, but I have never seen any proof. Countless hobbyist books, magazines, and products offer these guidelines, but none offer any evidence. I believe that we have, in effect, the perpetuation of a hypothesis that never been tested.

beviking · Post by **beviking** » Fri Oct 29, 2004 8:00 am

Bradimus wrote: In fact, the logarithmic nature of scale suggests that any guideline like that is flawed.

How so?

To change the pH 1 adds 10X the amount of H+ or OH- to the water (or at least frees them up). Aquatic organism are constantly dealing with osmotic pressure (transportation of water in/out of the organism) and the release/uptake of various substances/elements directly corrolate to this and are affected by numurous free radicals (including H+/OH-)in the water also (as I remember). Been out of school for a while but I'll try to dig up some substantiating material.

Bradimus · Post by **Bradimus** » Fri Oct 29, 2004 9:19 am

Compute the change in [H+] for the following swings

8.0 to 7.5
6.4 to 6.0

Why should one stress the animals but the other won't?

beviking · Post by **beviking** » Mon Nov 01, 2004 3:44 pm

I think the ".5 rule" (which I'm unfamiliar with) is one of those general guidelines, not a carved in stone rule.
"Stress" is a broad term, can be cumulative, may or may not persist, and does not necessarily mean death. I'm sure you are quite familiar with this also.

That said, oddly enough, citation to specifics of pH affecting fish is not as easy to come by, though admittedly I haven't looked too hard. There is plenty on TDS (total dissolved solids) and general hardness related to osmoregularity and the inability of cells to compensate for sudden changes...*breath*...resulting in cells rupturing.

Lets not forget that a swing in pH one way results in more or less H+, but also more or less OH-. Just seems like a lot of free radicals floating around to cause problems with any ion gradient. Still searching...

Bradimus · Post by **Bradimus** » Mon Nov 01, 2004 5:31 pm

beviking wrote:That said, oddly enough, citation to specifics of pH affecting fish is not as easy to come by

This is my point. There are countless guidelines in the hobby, but little hard science.

It is my opinion that changes in pH, so long as the water does not become too acidic or too basic, do not directly affect fish in a significant way. The danger is in what effect the change has on the rest of the water chemistry. If there is NH4 in the water and pH rises above 7.5, fish start to die. If there is NO2 in the water and pH falls below 6.5, nitrous acid starts reaking havok. And so on.

beviking · Post by **beviking** » Tue Nov 02, 2004 7:12 am

"That said, oddly enough, citation to specifics of pH affecting fish is not as easy to come by "

I knew that was coming back! Thought I would give you the opportunity to say "I told you so" before I said "Ah ha! Now I see what you're getting at!" or something along those lines. To which I have to agree that..."changes in pH, so long as the water does not become too acidic or too basic, do not directly affect fish in a significant way. The danger is in what effect the change has on the rest of the water chemistry...."
So the ".5 rule" suggests (given the above) that a change in pH >.5 can affect water chemistry enough to stress fish (or shrimp?) to the point of death?

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