Fish and pH

10 years ago

I have a new pond, about a month old, and last weekend I introduced some comet goldfish. Comets seem to be successful pond fish around here.

I floated the bag of fish in the pond water for a couple of hours to bring the water temperatures closer, then released them into the water. They all died almost instantly. One lived about 72 hours and he was the last.

I bought a water testing kit and checked out okay for phosphates, amonia, and nitrites, but the pH reading was above 9, how much above I'm not sure. Regardless, I've got very hard well water in the pond.

Could high alkalinity cause the fish to die so quickly? What is the best way to bring the water into better balance? I have been reading that chemical solutions can cause "pH crash" and cause even more problems.

Pond photo attached... thanks for your help!

Photo sucks: it starts as a waterfall at the top, which falls into a ~15' stream. The stream narrows to increase velocity when it goes over the second, short falls into the upper pond. There is a narrow cascade down into the lower pond, which is about 12x17'. I dug it too shallow so the whole thing is about 1,000 gallons, I think.

This post was edited by napalm_beach on Sat, Sep 14, 13 at 14:25

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Comments (4)

sleeplessinftwayne
10 years ago
If you put fish that had been in a bag containing water with low or neutral PH into water that was high PH then they would suffer the results of PH change immediately no matter what the temperature was. High PH is not normally a problem for comets but a sudden change is a problem.

The solution could have been making sure the pond's PH was lower or at least close to optimal, which is difficult, and/or slowly over a fairly long period (those two hours or more)adding pond water to the water in the bag a little at a time to reduce the shock. That is much easier.

In your photo I notice the rock around your pond and stream seems to be all limestone. It is unlikely you will be able to reduce PH to a noticeable extent. Don't waste your money trying over the counter cures. You will go bankrupt.

There are some discussions on PH in the saved conversations that you can access by using the search feature at the top of the thread or forum.

Here is a link that might be useful: pay attention to drh1.
napalm_beach
Original Author
10 years ago
Thank you, that makes perfect sense. I didn't think about conditioning them to the ph. Doh!

The pond is about 60% granite (mostly upper) and 40% basalt (basically, a dense lava rock). The basalt can be very alkaline, as is our water.

Really appreciate your help!
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chas045
10 years ago
I suppose the dramatic pH shift was the cause of death. However, sodium bicarbonate is cheap and as the link including drh1 says; you can add lots of bicarbonate without risk for minimal expense. The link keeps referring to raising pH but as drh1 mentioned near the beginning, bicarbonate will buffer the pH at pH 8.3. That means the pH will be pulled back towards 8.3 whether added chemicals are more acidic or more basic. A pH of 8.3 is fine for fish.

On the other hand, if morning pH was much nearer to 7, then you have a non pH problem.
Mike56
10 years ago
Your problem may be floating the bag for two hours. The fish may have used up all the oxygen in the water and the bag. A pH of 9 should not be a problem. But the spread could be.
Next time you add fish, Put the fish into a 5 gallon bucket and check the pH of the store water to see how far it is from yours. Add small amounts of pond water every 15 minutes to adjust the temp and pH until the pH in the pale is at least 8. Then add the fish to the pond. I use a net to move the fish to keep potentially bad store water out of the pond.
Mike