Rising PH in my 46 gallon

[push350z]

I've been doing my weekly WQ checks and this week my PH has increased by .4-.6. Previously my PH rested and was pretty stable at 7.6. Right now my PH is at 8.0-8.2, I have not added anything to the tank recently that could have possibly leeched and caused the PH to increase. The only new addition to my tank so to speak is a diatom bloom that started a couple weeks ago, could that be the cause? My tap water does have a high PH, it tops off the high ph scale on my API test kit, but before the oxidation of the water by bubbles and my HOB reduced the ph to a stable 7.4-7.6. What else could it be? The fish don't show any signs of stress what-so-ever so I may just monitor it closely and ride it out and see what happens.

 

[kostasonia]

It would be interesting to know the values of kH and GH too..Maybe you can do small PWC (e.g. 5% every 3 days) and add RO water instead of tap water...

 

[TomK2]

Tap pH can vary. Also, tap pH can not be checked right out of the faucet. You have to let it sit out overnight so that CO2 can equilibrate with the atmosphere. As CO2 enters or leaves the tap water, the pH will change.

Sounds like you have rather hard water. I bet you have moderate to high KH. My tank pH is pretty stable at 7.8. The good thing about high pH is that it is usually stable pH, and fish readily adapt to the higher but stable level. The pH recommendations for wild caught fish often do not apply to store bought fish, since many are commercially raised in water with parameters diffferent than in the wild, and so are readily adapted to the harder, higher pH so common in North America.

 

[7Enigma]

Algal blooms can most definately increase the pH levels in the tank (as can diatom outbreaks I would assume). While tap water does change from time to time, that is a pretty significant shift in pH which I believe is caused by your outbreak (since you have added nothing new to the tank).