Sudden Ph Drop

[Torred1771]

Yesterday, I did a small (10%) water change on my tank before adding my five banded barbs. Before the water change everything was fine. Literally hours later, I checked my tank to find one of my Black Phantom Tetras almost acting like it had swim bladder, doing rolls in the water and just floating upside down. It had lost absolutly none of its color and all the others were acting fine, as were the new barbs. I did an immediate water test, and noticed that my PH had dropped from 7.0 to 6.5!!! I do not understand why the ph dropped to quick as my tap water is 7. I used a ph buffer twice last night and once this morning and got it back up to about 7.2 but not sure why it dropped so fast...any advice?

 

[Prime Ordeal]

The water you added for the water change could have had a lower pH than normal...did you test it?

You've added a lot of stock in one go and they're all excreting CO2 at a high rate, due to stress, which lowers the pH.

For the long-term health and stability of your tank it's not a good idea to be dosing pH buffer. Get some crushed coral or oyster shell or coral sand and put it in your filter. That will raise the pH and stabilise it.

 

[Rummynose]

Not too long ago I had a similar problem. I used to change 80% of the water every 8-10 days because my nitrate levels were between 5 and 10 at all times. I thought what a great job I was doing and all of a sudden a lot of my fish died after one of those water changes. Ammonia, Nitrite and Nitrate were fine. Days later I was still trying to figure out what the cause could have been and thought to check the ph.

The ph in my tapwater is around 6.5 and the ph in my tanks was around 5!!!! I killed those fish when I did the large water change, the ph difference was too big.

My city has very soft water, so all I needed to do was add crushed coral to my filter. I now change 30% of the water every 4-5 days and my ph is stable.

I had come across this article when I was doing research about ph in aquariums, it is a long read but it helped me understand what goes on in a closed system like a fish tank: http/www.bestfish.com/oldtank.html (this is the second thread I've posted this site lol)

 

[Prime Ordeal]

I had come across this article when I was doing research about ph in aquariums, it is a long read but it helped me understand what goes on in a closed system like a fish tank: http/www.bestfish.com/oldtank.html (this is the second thread I've posted this site lol)

Hopefully you noticed the glaring errors in the article:

"...the low pH actually protects the remaining fish by keeping the ammonia in the non-toxic ammonia (molecular) form instead of the very toxic ammonium (ionic) form!"

and

"...if the aquarium has already gone into the low pH / high ammonia phase, a rise in pH will change non- toxic ammonia into lethal ammonium and lead to catastrophe."


And this was published in an aquarium magazine. Eek!

Otherwise a good article.

 

[Rummynose]

I had come across this article when I was doing research about ph in aquariums, it is a long read but it helped me understand what goes on in a closed system like a fish tank: http/www.bestfish.com/oldtank.html (this is the second thread I've posted this site lol)

Hopefully you noticed the glaring errors in the article:

"...the low pH actually protects the remaining fish by keeping the ammonia in the non-toxic ammonia (molecular) form instead of the very toxic ammonium (ionic) form!"

and

"...if the aquarium has already gone into the low pH / high ammonia phase, a rise in pH will change non- toxic ammonia into lethal ammonium and lead to catastrophe."


And this was published in an aquarium magazine. Eek!

Otherwise a good article.

Hmmm, no, I did not notice that. I read it as that the low ph was making the ammonia less toxic. But I see what you mean, about the error claiming ammonium being very toxic. I wonder if the words "ammonia" and "ammonium" were mixed up by whoever was in charge of the printing!? If you were to change those back around it would scientifically be correct, would it not?

 

[Torred1771]

I think I found the cause of my Ph drop, my tap water tested at 6.5. Now I know I need to buffer the tap water before it goes into the tank as well as dechlorinate.

 

[squeeky_jane]

Can I also give you an other suggestion......the wood in your tank? Is that new? I have found in my tanks, that when I had a lot of it, it dropped my pH level to similar levels. Just pointing out something that may or may not be an issue!

 

[Torred1771]

The wood was new when I put it in yes.

 

[Torred1771]

Just something I thought I would run passed you guys. I left some tap water out over night an tested it this morning at 6.0 so now I know why the ph in the tank dropped. One of the people that work at my LFS, said its best to do a water change during the week because the people that work at the water company "chuck in extra chemicals" on a friday to last through the weekend. Could this be true??

 

[TwoTankAmin]

Prime, once again your are 100% wrong. Both of those facts are correct.

Once the pH in a tank drops under 6.5 Ammonia become a rapidly decreasing concern. At 6 or below is ceases to be an issue. Raise the pH back up in short order and the ammonia returns to being toxic.

This is why so many people who have fish shopped in and then proceed to acclimate them in the bags have problems. If you fail to test the pH of the bag water, you will have no idea how low it may have gotten during the trip and thus no idea if adding your water will raise that pH and likely cause the water to become toxic. I have shipped many, many 100s of fish out over the last decade and have always added a small amount of Amquel to the shipping water to prevent any possible ammonia toxicity during the trip.

Anybody who gets fish recently imported from acidic waters knows these facts.

Prime-I would once again to very happy to provide links to dozens of reputable sources which will refute what you have said. Save me the trouble and link me to any which support what you have said.

Well here is one gratis, it shows a rise in pH from 7 to 9 over 12 hours resulted in an increase of 63 times (temp rise accounted for 10% of that increase, pH change accounted for the other 90%.

Daily pH Cycle and Ammonia Toxicity

World Aquaculture, 34(2): 20-21.​

​

(view also as PDF)

William A. Wurts, Ph.D.

Senior State Specialist for Aquaculture
Kentucky State University CEP at the UK Research and Education Center
P.O. Box 469
Princeton, KY 42445-0469

www.ca.uky.edu/wkrec/Wurtspage.htm​

​

Ammonia is a nitrogen waste released by aquatic animals into the production pond environment. It is a primary byproduct of protein metabolism. Ammonia is excreted directly from the fish gill into the water. Ammonia concentrations are usually at their highest late in the production season when biomass of the cultured species and the amount of protein fed are greatest. Ammonia is toxic to aquatic life and toxicity is affected by pond pH. Ammonia-nitrogen (NH[sub]3[/sub]-N) has a more toxic form at high pH and a less toxic form at low pH, un-ionized ammonia (NH[sub]3[/sub]) and ionized ammonia (NH[sub]4[/sub][sup]+[/sup]), respectively. In addition, ammonia toxicity increases as temperature rises.

From http/www.ca.uky.ed.../pH-Ammonia.htm