What would the ph be at 12dkh?

[Cory]

What would the ph of saltwater be when fully equilbriated with atmospheric co2 at an alkalinity 12dkh? 7dkh? And all other ph contributors are at nsw concentrations like borate for example.

An approximation is fine thanks

 

[Randy Holmes-Farley Verified Community Expert]

12 dKH = 4.3 meq/L ---> ~pH 8.4
7 dKH = 2.5 meq/L ---> ~ pH 8.2

 

[Cory]

12 dKH = 4.3 meq/L ---> ~pH 8.4
7 dKH = 2.5 meq/L ---> ~ pH 8.2

So can i equilibrate my tanks Co2 and dose baking soda or calcium hydroxide based on ph? It seems if ph is between 8.2 and 8.4 then alkalinity should be within normal range.

 

[Randy Holmes-Farley Verified Community Expert]

I wouldn't assume that any reef tank is fully equilibrated with home air. If they were, there would be no pH swing.

 

[Cory]

I wouldn't assume that any reef tank is fully equilibrated with home air. If they were, there would be no pH swing.

But if there was no ph swing and it was equilibriated with atmospheric Co2 at all times you could control alk this way?

What if i set up an apex with ph probe and set it to turn on at ph 8.19 and turn off at ph 8.30 with a sodium carbonate solution. Would it work in this case?

 

[Randy Holmes-Farley Verified Community Expert]

Theoretically yes, but I don't think you'll have stable alkalinity in a normal reef tank this way.

FWIW, I monitored my ATO limewater delivery by pH. When it wasn't what I expected, I knew there was a problem.

 

[Cory]

Theoretically yes, but I don't think you'll have stable alkalinity in a normal reef tank this way.

FWIW, I monitored my ATO limewater delivery by pH. When it wasn't what I expected, I knew there was a problem.

Yes i guess photosynthesis would be the biggest problem.

You monitored the tanks ph or the limewater? What kind of problems?

 

[Randy Holmes-Farley Verified Community Expert]

Yes i guess photosynthesis would be the biggest problem.

You monitored the tanks ph or the limewater? What kind of problems?

I had a pH meter in the water 24/7. So I could see the pH just walking by.

Low pH often meant the ATO ran out. High pH usually meant a water loss (or collection) somewhere that was being replaced by limewater. Both happened a few times over the years. lol

 

[Cory]

I had a pH meter in the water 24/7. So I could see the pH just walking by.

Low pH often meant the ATO ran out. High pH usually meant a water loss (or collection) somewhere that was being replaced by limewater. Both happened a few times over the years. lol

Thats a convienent way to know if its empty or losing potency without opening it.

Im currently dosing limewater via peristatic pump, the waters developed a caCo3 skin in my brute trash can. But its not keeping up with alk demand. Tank alk dropped to 6.5dkh the other day. My monties been growing lots lately. I expect due to the added no3 and zero on hanna po4. The ats keeps the no3 zero. Im worried the limewater in the brute trash can may have lost potency. Do you recall if the lid is off then the limewaters effectiveness to maintain alk/cal would be a significant drop? Or no effect?