PH levels

[Beldarr]

For a few weeks now, my PH has been 7.8

I have bought test kits for phosphates, carbonate hardness, and all the other normal tests like alkalinity, ammonia, etc.

All the tests are normal or within normal ranges.

I have done water changes, and even added my own RO/DI water system.

Any ideas on why it's running in the lower range?

 

[downbeach]

Good article here:

http://reefkeeping.com/issues/2004-09/rhf/index.php

 

[hkgar]

Almost always it is CO2

 

[Sk8r]

Quoting from another answer: "PH is not usually worth worrying about in a marine tank, unless you have special problems, like a tank in a basement with a furnace. It normally is up and down during a given day. A better guide is alkalinity, which should ride around 8.3, and which is achieved by buffers in your salt mix, by water changes of 10%, or by additional buffer: it exists in a 3-way relationship: calcium and magnesium in solution, and an alkalinity maintained between 7.9 and 8.3, whether through water changes or the addition of buffer. If you have stony corals, their use of calcium will continually pull at that balance, so we add both calcium and mg as time passes. My sig line has typical stony coral readings, which will hold water in a 'lock' of the relationship between alk, cal, mg.

If you do have special reason to worry about ph, that's a different situation; but if an ordinary tank in ordinary circumstances, track alk instead of ph."

And: if near furnace, fireplace, etc, that may push it low. If you end up doing stony coral, your kalk addition will probably push it that .1.

 

[nuxx]

Don't worry about it if it's stable.

That being said, when we increased our salinity from 1.023 to 1.026 and increased the light to our chaeto our PH went up from 7.8-7.9 to 8.1-8.2.