Temperature Shock?

12726 Views 5 Replies 4 Participants Last post by pop, Jul 2, 2014

Diver Down

Discussion Starter · Jul 1, 2014 (Edited)

I lost a 6 month old Zebra Danio today following a routine 25% weekly water change. He shared a 20-gal tank with two other Danios and six tetras (Rosie and Red Phantom). The whole gang seemed fine before the water change, but all were acting panicked right after. My first thought was to look at the water temp, which it turns out had risen about six degrees. I keep the tank at 76, and my thermometer was showing 82. A few minutes later the Danio was dead, and one of the tetras was lodged at the base of an Anacharis, breathing but not moving. Now the tetra is swimming again, but he is still weak.

I also tested Ammonia, Nitrites, and Nitrates after discovering the problem. Zero ammonia, zero nitrite, 20ppm Nitrate. That's typical for my tank. Also tested pH. Read 7.2, which is a bit below typical, which is 7.4.

So, could a six degree rise cause such a sudden trauma? Nearly instant death? Clearly, the water I added must have been considerably warmer than 82, if it caused the blended temperature to rise to that level. But the water I added felt cool to the touch, with a slight stream of warmer water mixing in. Certainly not hot. I fill the tank from my tap (separate hot and cold valves mixing in one faucet), testing and adjusting the temperature beforehand. It's not an exact method, and sometimes the pressure on one of the two taps will drop after I start filling, changing the blended temp. That may have happened this time; the only evidence I have is the temp rise.

-DD

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pop

· #4 · Jul 1, 2014

Hello:
I am not challenging you all assessment but this loss of fish due to temp change 6 degrees is hard to understand. One might think that since only one critter passed on why didn’t the other aquarium members also pass on if loss was due to sudden slight temp change of six degrees.

I think you had to add very warm water to you 20 gal tank to raise the temp that much. I would check the heater. When I do water changes I use cold water unless I am doing a 50 % or greater water change.

the sudden change in pH could be connected to the problem by way of tds shock. there are some good articles about total dissolved solids and total suspended solids in the article section.

pop

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pop

· #6 · Jul 2, 2014

Hello Diver Down:

I cannot offer much help or any valuable suggestion due to my lack of knowledge and experience. My understanding of pH is that pH 7.2 is two times more acidified than a pH of 7.4. Another way to view the difference is that pH 7.4 has twice the amount of hydroxyl ions as hydrogen ions making the solution alkaline. When pH change is integers (whole numbers) the difference is tenfold, so a pH of 8 is 10 times more alkaline than pH of 7.0 and a pH of 9 is 100 times more alkaline than pH 7.0

To answer your question small changes in pH can represent large differences in the concentration of the hydrogen / hydroxyl ionic relationship.

How pH impacts water critters I don’t understand.

pop
(In Bryon's article on tds the effects of CO2 on pH is not considered)

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