Terra cotta clay pot raise ph in tank?

[thorpbrian]

I just set up my 55 gal tank on Monday. I'm cycling it with fish using Tetra Safe Start, gravel and decorations from my other tanks.

When I set up the tank I put in some plastic plants, a roman coliseum decoration, a bag of gravel from my other tank and a terra cotta pot that I got at the hard ware store (washed and scrubbed with warm water first of course).

Yesterday I've noticed that my PH is at 8 (I'm not testing the other parameters nor giving them here since I'm cycling with TSS). This is weird because the ph from my tap is 7 and the ph in all my other tanks is 7. My logic tells me that the terra cotta pot is raising my ph.

So my question is will the terra cotta pot raise my PH? Has anybody else had an experience like this?

On a side not I've since taken the terra cotta pot out from the aquarium and added some driftwood that I had been preparing for the tank.

 

[lime_smash]

I have used terra cotta pots in my tanks and have had no pH fluctuations, but you never know. I would take it out test submerse it in a separate bucket for a day and test the pH of that water. If there is a pH fluctuation there then i probably wouldn't keep it in the tank.

Also, if you are using mopani wood in your other tank that may lower your pH a bit.

 

[Rbishop]

Never had an issue with them...

 

[jpappy789]

Did you wait 24 hours to test the sample of tap water? Is there anything in the other tanks that could be lowering the pH? What test brand are you using?

 

[thorpbrian]

I use API master test kit. There is nothing in my goldfish tank to lower the PH and it tests at 7.0. I have driftwood in my 20 gal community and it tests at about 6.8.

I'm almost 100% certain it was the pot now. I've since taken it out, boiled it in water and then tested the PH of the water it was boiled in. The water which tested at 7.0 before I boiled it tested at 7.6 after the pot was boiled in it. The water tested at 7.0 before I put the pot in and was at 8 two days later. All the other decorations besides the gravel had been used in other tanks. I took vinegar and put it on the pot and it fizzled a little bit. Not sure why this particular pot is causing this because I now it is pretty common practice to use them but I'm not going to use it.

I'm going to go with a rock cave instead in that tank...

 

[omplmpa3]

Is the whole pot terra cotta clay? I use terra cotta is some of my tanks and I have never had a ph problem. Going from to 7 up to 8 is a pretty big increase.

 

[jm1212]

terra cotta should be inert...

boiling water will cause the pH to rise because it drives out extra CO2 and concentrates any minerals that are in the water.

 

[thorpbrian]

It's not too big an issue. I've removed the pot and have decided to use sandstone rocks (which I tested and didn't react to vinegar) to make a cave for my future cichlids instead. I'll get the ph back down with water changes. The fact that the pot reacted to vinegar makes me think that the clay used to make the pot had something in it that is leaching into the water.

This actually turned out well for me because I like the look of my tank much better now.