What causes high PH?

[Capecliff]

Do nitrates cause ph to rise? Mine has been steadily rising. Now it's at 8.65. A water change two weeks ago brought it back down, but just a bit, to 8.4. What causes it?

I stopped adding bionic months ago

[ckeadle]

I am curious as well.... What causes the PH to rise?

Mine is at about 8.65 now, it seems to have steadily increased since I added the GEO calc reactor about 1-2 months ago.

Any ideas?

[ReefHawk]

I'm not sure overall, but I do know that Ca makes the ph rise. Thats why we "drip" kalk and many do so at night as the ph normally drops then after the lights go out.

[MrSandman]

A calcium reactor should not drive pH up....rather it would drive it down. The effluent pH coming out of a calcium reactor is around the 6.5 range. Now, if you were talking about a kalk reactor, then thats a different story. Kalkwasser will drive your pH up. I too thought that my pH was getting a bit too high via my Pinpoint monitor...i then changed the batteries and found that it was right on target. So, to those of you using a Pinpoint to monitor your pH, and you've been getting high readings..try changing the batteries. FWIW.

[MIKE]

Hi Gang,

Ph is, in simple terms, a function of the balance between hydrogen and hydroxide ions in the system.

In practical terms, there are usually three key elements that commonly affect tank ph.

1. Measurement. Measuring ph is a very fine and delicate job. The equipment/tests available to hobbyists are frankly estimates at best. The colormetric tests are can easily be off .4 +/-, and monitors must be maintained and calibrated to stay within their stated accuracy ranges. Most ph readings that hobbyist get are just not accurate.

2. Air exchange. For practical purposes, if your tank doesn't have good circulation then co2 can accumulate and cause a downward pressure on ph. Conversely, if you have an abundance of fresh air exchange and/or heavy photosynthesis (plants/animals consuming co2 and releasing o2), ph will have more of an upward bias.

3. Chemical makeup. Again, in practical terms this is primarily carbonates and how much. However, this is rarely an issue in most current tanks. As long as alkalinity remains somewhere in a range of 2-15 dkh, ph will remain pretty unaffected by the amount of carbonates. Rather, the higher alkalinity will help the system resist ph fluctuations more readily, but level of ph will not be materially affected. Shoot, I've seen tanks with virtually zero alkalinity and still ph 8.2. The notion that "my ph is low so I have to add buffer to increase it" is just not true. I would also include in this heading other chemicals that may temporarily affect ph such as sodium carbonate, kalkwasser or b-ionic.

So, to the question. My first guess would be that your ph is high because of inaccurate measure. Assuming measure is accurate, the next likely explanation would be that you have great gas exchange and/or lots of photosynthesis. Finally, the last possibility would be that you have alkalinity that is very high, likely above 18 dkh or so. Either way, I wouldn't worry about it as it's not that high. If you get readings of 9 or so, then I'd investigate.

HTH