sodium hydroxide and low ph

[alpenreef]

Good morning,

I have been dosing NAOH and All for Reef for about 2 weeks and I am not observing any bump in ph. It stays under 8.0.
210 gallon system volume. I am maintaining alkalinity at 10.5 which is roughly what my salt mixes to.
I dose daily 0.5 dkh which is my consumption rate. I split this 50/50 between NAOH and All for Reef daily:

10 ml of NAOH at Randy’s 275g/l concentration
40 ml of All for Reef

This seems to keep my alkalinity and calcium stable but has no influence on my low 7.9 ph. Is it because of my tank’s high alkalinity and buffering ability?

 

[elysics]

Good morning,

I have been dosing NAOH and All for Reef for about 2 weeks and I am not observing any bump in ph. It stays under 8.0.
210 gallon system volume. I am maintaining alkalinity at 10.5 which is roughly what my salt mixes to.
I dose daily 0.5 dkh which is my consumption rate. I split this 50/50 between NAOH and All for Reef daily:

10 ml of NAOH at Randy’s 275g/l concentration
40 ml of All for Reef

This seems to keep my alkalinity and calcium stable but has no influence on my low 7.9 ph. Is it because of my tank’s high alkalinity and buffering ability?

0.5 just isn't much and then you split it in half. If you do all of it through naoh maybe you'd see an effect of 0.1 or so. You'd have to dose calcium etc through other means as well then though.

And I don't know what dosing schedule you have and how high in CO2 your room is, but the effect is only temporary, the pH goes up after dosing and then goes down to what it was over the course of an hour or so

Do you even have a pH probe or are you measuring with a test, and when relative to when dosing happens

 

[alpenreef]

0.5 just isn't much and then you split it in half. If you do all of it through naoh maybe you'd see an effect of 0.1 or so. You'd have to dose calcium etc through other means as well then though.

And I don't know what dosing schedule you have and how high in CO2 your room is, but the effect is only temporary, the pH goes up after dosing and then goes down to what it was over the course of an hour or so

Do you even have a pH probe or are you measuring with a test, and when relative to when dosing happens

Baby steps

0.5 just isn't much and then you split it in half. If you do all of it through naoh maybe you'd see an effect of 0.1 or so. You'd have to dose calcium etc through other means as well then though.

And I don't know what dosing schedule you have and how high in CO2 your room is, but the effect is only temporary, the pH goes up after dosing and then goes down to what it was over the course of an hour or so

Do you even have a pH probe or are you measuring with a test, and when relative to when dosing happens

I dose 4 times a day, room co2 is 700.
I do draw in outside air into my skimmer otherwise my ph would be 7.8 on average.

 

[Garf]

It's a matter of consumption of alkalinity. As soon as your tank consumes more naturally, the higher you can run pH. Then the higher the pH, the more likely the tank is to suck in more CO2.

 

[alpenreef]

It's a matter of consumption of alkalinity. As soon as your tank consumes more naturally, the higher you can run pH. Then the higher the pH, the more likely the tank is to suck in more CO2.

That sounds like an excuse to get more sps

 

[Randy Holmes-Farley Verified Community Expert]

If you add 1.4 dKH of alk by hydroxide instantly, the pH boost is about 0.65 pH units. If you spread that out over multiple doses, the effect is much smaller.

If you add 0.25 dKH, as done here, the effect of an instant addition would be about 0.1 pH unit, and will be very small a few hours later.