Should I adjust pH or alkalinity first or both together?

[peterhos]

Hi All Thanks for help on this. Firstly what should I aim at here? PH of 8.3(??) and ideal alkalinity of …?? Then which should I adjust first? Or can you do both together? I am going to use sodium bicarbonate. Will that help with both or am I missing something here? Many thanks.

 

[ScubaShane]

We need to see your test results but don't worry about chasing you PH. Main focus is keeping Alk and Cal stable. My PH stays between 8.4-8.5. I wouldn't try mixing sodium bicarbonate up. I would recommend just using something like Seachem Reef Fusion 1 and 2. Easier and less room for error.

 

[Randy Holmes-Farley Verified Community Expert]

Sodium bicarbonate lowers seawater pH while adding alkalinity, and there's nothing you can dose to boost pH which does not add alkalinity.

 

[Randy Holmes-Farley Verified Community Expert]

We need to see your test results but don't worry about chasing you PH. Main focus is keeping Alk and Cal stable. My PH stays between 8.5-8.7. I wouldn't try mixing sodium bicarbonate up, you can but I would recommend just using something like Seachem Reef Fusion 1 and 2. Easier and less room for error.

I strongly expect your pH is in error if you really mean that using Seachem Reef Fusion, your pH ranges from 8.5 to 8.7, assuming you have a normal reef tank with even halfway decent aeration.

 

[ScubaShane]

I strongly expect your pH is in error if you really mean that using Seachem Reef Fusion, your pH ranges from 8.5 to 8.7, assuming you have a normal reef tank with even halfway decent aeration.

No I don't use Seachem. Just recommending something easier to use with slower results. Natural sea water has a PH of 8.5. The oceans generally have a higher alkalinity due to carbonate content and thus have a greater ability to buffer free hydrogen ions. I keep my Alk on the high side for greater coral growth and health which inturn keeps my PH around 8.5.

 

[peterhos]

Sodium bicarbonate lowers seawater pH while adding alkalinity, and there's nothing you can dose to boost pH which does not add alkalinity.

Thank you for the advice. I had better sort salinity first in the new tank. Have only just worked out that calcium and magnesium are sky high due to relying on a very old refractometer. A lesson to all! Make sure your initial readings re reliable.

 

[Randy Holmes-Farley Verified Community Expert]

No I don't use Seachem. Just recommending something easier to use with slower results. Natural sea water has a PH of 8.5. The oceans generally have a higher alkalinity due to carbonate content and thus have a greater ability to buffer free hydrogen ions. I keep my Alk on the high side for greater coral growth and health which inturn keeps my PH around 8.5.

That is not correct. The pH of natural seawater is 8.1 to 8.2 when equilibrated with normal air. I believe your pH measurements are off as well.

The alk of normal seawater at 35 ppt is well below 7 dKH.

 

[ScubaShane]

That is not correct. The pH of natural seawater is 8.1 to 8.2 when equilibrated with normal air. I believe your pH measurements are off as well.

The alk of normal seawater at 35 ppt is well below 7 dKH.

Today's ocean PH reading from NOAA is 8.47 there is more Borax in the ocean than there was 10 years ago.
My readings are
77°F
35ppt
9dkh
410ppm
1320Mg
8.2 mg/l Sr
PH8.6
salt compounds Na2B4O7·10H2O

 

[Randy Holmes-Farley Verified Community Expert]

Today's ocean PH reading from NOAA is 8.47 there is more Borax in the ocean than there was 10 years ago.

This is just utterly wrong.

This is what NOAA says about pH:

Ocean acidification

In the 200-plus years since the industrial revolution began, the concentration of carbon dioxide (CO2) in the atmosphere has increased due to human actions. During this time, the pH of surface ocean waters has fallen by 0.1 pH units. This might not sound like much, but the pH scale is...

www.noaa.gov

"The ocean’s average pH is now around 8.1, which is basic (or alkaline), but as the ocean continues to absorb more CO2, the pH decreases and the ocean becomes more acidic."

The borax comment is also simply incorrect in this context. Boron is considered a conservative ion which means that its concentration in the ocan depends only on salinity (unless you are near the mouth of a river), and its value has not varied at all during our lifetimes in any way that impacts ocean pH or alkalinity. It's contribution to total alkalinity is fairly small, but not insignificant since it is the third largest contributor to total alkalinity after bicarbonate and carbonate.

Boron and Marine Life: A New Look at an Enigmatic Bioelement - Marine Biotechnology

On the occasion of the 200th anniversary of the discovery of boron, we review the oceanic biogeochemistry of boron as well as suitable analytical techniques for its determination. This overview includes aspects of biogeochemistry including geochemical stable isotope variations, uptake...

link.springer.com

" In seawater, inorganic boron content generally bears a linear relationship to chloride content. A ratio of 0.00024 g boron/g of total halogen expressed as chloride ion has been calculated (UNEP 1998) with dissolved species comprised largely of partially dissociated boric acid along with weakly associated ion-pairs of neutral and positively charged borate complexes of sodium, magnesium, and calcium."