High(er)/Rising ph

[seanadg]

Hi, I am new to this forum and, in fact, new to the world of fishkeeping, being a new betta owner for slightly over 24 hours now. I have a question about the increased ph in my tank, compared to the tap. First, some details. We have our betta alone in a 5 gallon Eclipse Hex, with a heater maintaining at 79 degrees and a filter built into the hood, one of those bio-wheels. I ran the tank for a few days before getting the fish to make sure all was stable. I am on a well, so no need for conditioners. Water from the tap tested at ph 7.0 several times over a few days so I felt comfortable I had a handle on that (used a test with the test tube). Water is slightly soft/hard at 120 ppm, low buffering at 80 ppm (used a strip test for these). Tested tank ammonia, nitrites, and nitrates 2x today with a strip test and all were 0. Strip test indicated ph was between 6.8 and 7.2. When I tested the tank water tonite with the test tube test, it came out at 7.6!! And that's the highest the test will go! I tested my tap water again, and that still reads 7.0. So - what is going on here?! What would cause the tank water to increase in ph? I know with the low buffering ability of my water that the ph may not be stable, so maybe I need to add a stabilizing agent. But I had expected the ph to go down as waste built up, ammonia built up. I did a 25% water change, but I didn't want to do total water change, I thought that might be too great a change for him. Your thoughts, guidance is GREATLY appreciated on this one!!

Thank you!

[amanichen]

Since you seem to be familiar with cycling already, I'll just give you a brief rundown of what's going on.

Carbon dioxide: some municipal water sources have lots of dissolved carbon dioxide which will temporarily lower the pH of the water. To test this, compare the pH of a freshly taken water sample, to one that was taken 24 hours ago. If the pH difference is greater than 0.2, then you might want to consider preparing water beforehand. Agitate the water for a few hours before it goes into your tank to help drive out excess CO2.

[seanadg]

Okay thanks, I'll do that. I am on a well, though, so it can't be anything added - at least nothing added by humans! Could well water have excessive CO2 in it?

I've checked it a few times now and sometimes it seems to be between 7.2 and 7.6 (at least between the colors corresponding to those ph levels on the chart) and sometimes closer to 7.6. I am using an Aquarium Pharm test.

Thanks so much, it's a relief to know there's someone I can turn to when so worried - and new to all of this!!

[amanichen]

Do the 24 hour comparison as I described above. If there's no difference in the pH, then we'll look to other causes.

[iemsparticus]

Actually, most well water contains very high amounts of CO2, so that could very well be the reason your pH is increasing.

[seanadg]

Ahh, said grasshopper! I had no idea and after doing some more searching on the web, I saw a few references to CO2 so thanks for sending me in that direction. I'll test tonite and again tomorrow night (one of the sites I found suggested 48 hours to allow CO2 to evaporate) and then I'll have more information to share. I had no idea well water would have more CO2 and that it could affect ph like that.

Thanks so much! I am relieved to have a plan!

[seanadg]

YOU GUYS ROCK!!! I tested the 24 hour water tonite and sure enough, it is around 7.2. Straight out of the tap, it is still 6.8-7.0. I am going to test it tomorrow night too, I'll bet it's closer to 7.6, which is what I get from the tank. I am also going to buy a high ph test kit, just so I have peace of mind that it's not rising even higher.

If I just leave water out for 2 days, do you think that's sufficient time to allow the CO2 to evaporate? Is there anything else I should consider?

Thanks again!!