PH spike

[Coco60]

Hi. I started my 40gal planted tank three months ago. Now Cycling ok, PH 7.0 ammonia 0, Nitrite 0, Nitrate 5ppm, CO2 injection. Three weeks ago added six neons and a week later six red eye tetras. Today testing water parameters, my PH jumped to 7.8 ! it has been 7.0 all the time ! even if small fishes, could the livestock addition be responsible ?

 

[Aiken Drum]

The natural processes in an aquarium like fish respiration tend to acidify water. Plant respiration does raise pH, but overall the trend is for pH to get lower over time.

Are you comparing the 2 pH levels you mention at the same time of day. For instance you dont normally run CO2 when the lights are off, so you would get a different pH when the lights are on and the CO2 is running compared to when its off due to different concentrations of CO2.

Anything else added to the tank? Maybe some new rocks that raise pH. Might the pH of your source water have changed?

Did this change happen suddenly or gradually over the last few weeks? Any other differences in tank conditions, time of day etc, between the lower and higher reading.

It could just be your set up settling down and thats where it wants to be. Is your pH a problem. That does sound a high pH for a tank with functioning CO2 injection.

 

[Andy Sager]

Hi. I started my 40gal planted tank three months ago. Now Cycling ok, PH 7.0 ammonia 0, Nitrite 0, Nitrate 5ppm, CO2 injection. Three weeks ago added six neons and a week later six red eye tetras. Today testing water parameters, my PH jumped to 7.8 ! it has been 7.0 all the time ! even if small fishes, could the livestock addition be responsible ?

Not really. Ph changes are often caused by the addition of extra aeration, calcium based decorations or substrate, removing an acid based decoration, the addition of salt or stabilizing salts. If anything, adding more fish would make the Ph go down due to the addition of more ammonia produced by the fish.
With that all said, tanks can have Ph swings throughout the day. When plants absorb the CO2 from the water, it can raise the Ph some.
So the question is, did you add or remove any decoration?
Increase the aeration?
Reduce CO2?
Change the GH or KH of the water?
Did the water source change their water parameters?

 

[Coco60]

No same plants and syriu rocks and drift wood, Neosoil.I've increased a bit my CO2 three days ago. Stream pump at night(surface agitation)for air exchange. Kh:71ppm, GH: 143ppm. Tap water at 7.9 since beginning. my PH test was taken once one hour after light came on(as usual).My CO2 and lighting are programmed to work oppositaly.I tested PH seven days ago at 7.0 and steady for two past months. But today 7.8 !! Could it be my wood and soil not making the water more acidic anymore !!!

 

[Colin_T]

It's unlikely to be wood, ornaments or substrate raising the pH but could be. You would have to test these items individually in buckets of tap water. Test the tap water for pH, GH and KH at the start of the tests and a week later. Have one bucket of water with just water in and nothing else and test that too. See if anything changes the pH, GH or KH.

Did you get a new bottle of CO2?
Maybe someone mis-labelled the bottle.

CO2 is acidic and naturally drops the pH.

Test your tap water for pH, GH and KH. The water company might have used a different water source or added more KH buffer to the water and this is pushing up the tank water pH.