pH math help!

alimac122

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Changing pH from 7.5 to 8.3

So I would like help on my math calculations.
I am using KOH to increase my pH
I know to not bump the pH more than 0.5/day.


heres what I have so far:
Initial pH: 7.5
[H+]= 3.16x10^-8 mol/L
405L in tank = 1.28x10^-5 moles

Desired pH: 8.3
[H+]= 3.16x10^-9 mol/L
405L in tank= 2.03x10^-6moles

Change in moles= 1.077x10^-5 moles

addition of 0.85M KOH (assume 100% dissociation)
1.077x10^-5moles/ 0.85M= 1.26x10^-5L OR 0.0126mL

This seems insanely small. And i know chasing pH is a horrible idea, but my pH has been perpetually low for a few months now and my corals have halted growth and the colors are fading. So any help on the math would be appreciated. If you would like to make suggestions on my tank as a whole, please leave comments on my build thread and not on this thread. Thank you-- much appreciated :) (((suggestions always encouraged)))
 
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alimac122

alimac122

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Randy Holmes-Farley

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You will not be able to calculate a pH rise in a buffered system like seawater without far more complex equations, and hydroxide is an alkalinity supplement and should only be used if you intend to raise alkalinity.

That said, adding hydroxide to 7 dKH seawater in sufficient amount to boost alk by 1.4 dKH will instantly boost pH by about 0.6 to 0.7 pH units, and then it will drop back as the tank pulls in CO2.
 

blasterman

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Fading corals has nothing to do with pH. Check phosphate and nitrate.
Low day pH will slow down SPS like acros but not hurt them.

I just tested some sodium hydroxide in my SPS heavy 20L and it doesn't take much to spike pH .3 points. However, its not the issue here.
 
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