pH keeps dropping- Why?

[Randy Holmes-Farley]

It is possible for the alkalinity to decline by 4 dKH in one day in a heavy SPS tank, and in 2-4 days in a medium stocked tank.

What happened in the aeration tests?

 

[SaltyTX]

It tells me CO2 is some of the problem, but not all of it because my alkalinity drops so far in such a short time.

I have some Kent Superbuffer dKh.

The first ingredient is carbonate, then bicarb, then a borate.

 

[mg426]

Have you tried a daily dosing regimen with a Good two part solution. Randys Homemade two part(recipe#1) works wonderfull for me. Maintain a steady alk level for several days, provide some fresh air and I bet your system will be AOK.

 

[96p993]

So what would be the bottom line PH that should be cause for real concern...Say we are talking full reef be it all SPS or mixed

 

[SaltyTX]

<a href=showthread.php?s=&postid=14732967#post14732967 target=_blank>Originally posted</a> by 96p993
So what would be the bottom line PH that should be cause for real concern...Say we are talking full reef be it all SPS or mixed

I think this would make a good new thread- But since I read it, I would say it depends if it is a constantly low pH or if it is a diurnal swing.

 

[Randy Holmes-Farley]

The Superbuffer would not be my first choice, both because it does not raise pH much and because of the borate in it. Limewater would be the best choice, followed by a high pH two part or baked baking soda.

IMO, pH concerns rise as the pH drops below 8.2, but reefs operate fine for a while. As the pH drops below 7.8 I get much more concerned. A bit lower than that and coral skeletons can begin to dissolve.

These have more:

The "How To" Guide to Reef Aquarium Chemistry for Beginners, Part 3: pH
http://reefkeeping.com/issues/2007-05/rhf/index.php

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

 

[SaltyTX]

well. Question-

Will a nutrient rich tank, undergoing a lot of decomposition (but efficiently to limit nitrates/nitrites/ammonia) destroy the alk/pH readings?

 

[Randy Holmes-Farley]

If nitrate is actually increasing (not just high, but increasing), then that can deplete alkalinity as it rises. If that nitrate is being taken back up into macroalgae, then there is no depletion. I discuss that here:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

A sulfur denitrator, however, will also deplete alkalinity.

pH is mostly driven by atmospheric CO2, but in tank sources of CO2 also impact it.

 

[SaltyTX]

well Mg levels are 1520ish

Ca is 340, a bit low.

wonderific.

 

[WaterKeeper]

<a href=showthread.php?s=&postid=14719044#post14719044 target=_blank>Originally posted</a> by SaltyTX
Ok.....I understand the article. And have talked with my wife who deals with aquatic water chemistry (recently published by the way )

Finally, someone who understands Randy but he did need to bring in a ringer.