Ph Higher In Tank Than From Tap?

[Callum]

hello ive done some ph tests which = my tap water is ph 7.1 yet my tank is about 7.5 is this normal i think i have a granite rock in my aquaqium could that be causing the higher ph or is this normal?

 

[rdd1952]

Granite shouldn't raise your pH but there are definitely rocks that will such as limestone. You can check the rock just to be sure. Pour some vinegar on it. If it fizzes, it's not a good rock to have. Is your tank cycling by chance? Ammonia will raise the pH too.

 

[Callum]

amm levels 0-0.1 here is a pic of my rock im not sure what type it is:

http/photobucket.com/albums/y131/xcaz/?a...rrent=tank3.jpg

 

[rdd1952]

If it's the big one on the right, it does look like granite. so it shouldn't be a problem. I don't see anything that looks like a problem either. By the way, nice looking tank.

 

[Callum]

thanks. its all getting rearrandes soon im adding some bogwood and a few more plants

 

[simonbrown403]

Granite is a composite of other rocks that have been compressed over the years by millions of tones, some times it can hole something limestone deposits inside, like said before test it with some vinegar to see if it fizzes.

Also is that a concrete decoration, some times they haven't been Left to cure properly, so there is still lime in it, which will leach out in to the water, again test it with vinegar

 

[Callum]

the castle is not made of concrete not sure what it made of stone + plastic is my guess

 

[freddyk]

Chances are that your tap water is a little low on oxygen and high on co2. water like this will show a lower ph right out of the tap. Once the water is in your ank and run through the filters or disturbed by air stones, the co2 is is driven out and oxygen is absorbed and the result is that the ph rises a bit.

If you want to test this to see if it applies to you, simply place tap water in a bucket and test the ph. Then run an air stone in it for 24 hrs and test again.

 

[CFC]

Freddy has hit the nail on the head, high pressure water mains inject a lot of C02 into the water which temporarily acidifies the water lowering the pH, as the water is aerated the C02 starts to escape from the water and the pH is able to rise back up to its normal level.

 

[rdd1952]

I had never thought of that. Now I've learned something new.