Kalk vs hydroxide PH elevating boost

[Miami Reef]

Is it true that limewater has a higher effect on ph because the calcium and alkalinity is extremely dilute in comparison to the high PH, resulting in more dosage per day?

Hydroxide is much more concentrated than kalk in alkalinity and calcium, which results in less solution dosed per day.

So is it true that fully saturated kalkwasser used in ATO has the highest effect on ph than all the other methods of 2 part?

 

[arking_mark]

Kalkwasser is Calcium HYDROXIDE.

 

[Miami Reef]

Kalkwasser is Calcium HYDROXIDE.

That’s what limewater is. :)

Technically limewater is Ca(OH)2 dissolved in water.

 

[Dennis Cartier]

I am not sure if sodium hydroxide has a bigger effect on pH or not. I suspect it has the same effect, but because it can be much more concentrated than saturated kalk, you are not limited by your daily evaporation limit and can dose as much as needed and gain the pH boost for the whole dose.

If you are able to stay under your daily evaporation limit, and meet you needs with only kalk, then it may be 6 of 1 and a half dozen of the other, when compared to using a 2 part based on sodium hydroxide.

I did a bit of googling, and my guess is that sodium hydroxide will have a bigger effect on pH than calcium hydroxide due to it's higher pKa. Randy will be able to say for sure.

 

[KStatefan]

I would bet that @Randy Holmes-Farley has an article with this data.

 

[Dennis Cartier]

I would bet that @Randy Holmes-Farley has an article with this data.

Always a safe bet! :)

 

[Randy Holmes-Farley Verified Community Expert]

Is it true that limewater has a higher effect on ph because the calcium and alkalinity is extremely dilute in comparison to the high PH, resulting in more dosage per day?

Hydroxide is much more concentrated than kalk in alkalinity and calcium, which results in less solution dosed per day.

So is it true that fully saturated kalkwasser used in ATO has the highest effect on ph than all the other methods of 2 part?

First, "hydroxide" has no concentration.

You can make sodium hydroxide as weak (or nearly as strong) as one might want.

Second, there's no significant change in the effect of hydroxide of any type on pH due to the concentration used as long as one adds the same amount of alkalinity in the same period of time.

If you add any type of hydroxide more slowly, the peak pH attained will be lower because the pH boost is spread out over a period of time that the aquarium can pull in more CO2 to offset the pH rise.

Thus, 1 dKH added in 3 minutes will give a much higher pH peak than 1 dKH added over 24 h.

If you use a two part made from sodium hydroxide, and dose it over the same period of time that you dose limewater (kalkwasser) and add that same total alkalinity, the pH effect will be the same.

One concern with adding any high pH additive (hydroxide, carbonate, silicate, etc.) too fast and too concentrated is that one is more likely to locally precipitate calcium carbonate, which is then wasted calcium and alk. Local precipitation and redissolution of magnesium hydroxide is normal, but you want to mix it in fast to prevent the slower precipitation of calcium carbonate.

 

[Miami Reef]

First, "hydroxide" has no concentration.

You can make sodium hydroxide as weak (or nearly as strong) as one might want.

Second, there's no significant change in the effect of hydroxide of any type on pH due to the concentration used as long as one adds the same amount of alkalinity in the same period of time.

If you add any type of hydroxide more slowly, the peak pH attained will be lower because the pH boost is spread out over a period of time that the aquarium can pull in more CO2 to offset the pH rise.

Thus, 1 dKH added in 3 minutes will give a much higher pH peak than 1 dKH added over 24 h.

If you use a two part made from sodium hydroxide, and dose it over the same period of time that you dose limewater (kalkwasser) and add that same total alkalinity, the pH effect will be the same.

One concern with adding any high pH additive (hydroxide, carbonate, silicate, etc.) too fast and too concentrated is that one is more likely to locally precipitate calcium carbonate, which is then wasted calcium and alk. Local precipitation and redissolution of magnesium hydroxide is normal, but you want to mix it in fast to prevent the slower precipitation of calcium carbonate.

This is amazing! Wow! Thank you!!!

 

[ReefAddict16]

First, "hydroxide" has no concentration.

You can make sodium hydroxide as weak (or nearly as strong) as one might want.

Second, there's no significant change in the effect of hydroxide of any type on pH due to the concentration used as long as one adds the same amount of alkalinity in the same period of time.

If you add any type of hydroxide more slowly, the peak pH attained will be lower because the pH boost is spread out over a period of time that the aquarium can pull in more CO2 to offset the pH rise.

Thus, 1 dKH added in 3 minutes will give a much higher pH peak than 1 dKH added over 24 h.

If you use a two part made from sodium hydroxide, and dose it over the same period of time that you dose limewater (kalkwasser) and add that same total alkalinity, the pH effect will be the same.

One concern with adding any high pH additive (hydroxide, carbonate, silicate, etc.) too fast and too concentrated is that one is more likely to locally precipitate calcium carbonate, which is then wasted calcium and alk. Local precipitation and redissolution of magnesium hydroxide is normal, but you want to mix it in fast to prevent the slower precipitation of calcium carbonate.

So the only difference is sodium hydroxide can be mixed at a higher concentration vs calcium hydroxide in a gallon container? If I remember correctly nothing more than 2 tsp of calcium hydroxide can be mixed in a gallon container.

 

[Miami Reef]

So the only difference is sodium hydroxide can be mixed at a higher concentration vs calcium hydroxide in a gallon container? If I remember correctly nothing more than 2 tsp of calcium hydroxide can be mixed in a gallon container.

That’s not the only difference.

Kalkwasser supplies both calcium and alkalinity in one solution while sodium hydroxide only supplies alkalinity.

Kalkwasser does not raise salinity over time while sodium hydroxide paired with calcium chloride does.

And yes, sodium hydroxide can be made much more concentrated than kalkwasser.

Hope this helps.

 

[Sisterlimonpot]

If you start supplementing sodium hydroxide alongside calcium hydroxide to help raise pH in attempt to stay under your daily evap. Is it wise to add a calcium supplement in order to maintain the ca and kh balance?

And a tangent to this idea, is there any concern with injecting NaOH into a kalk reactor that has fully saturated CaOH2? Would the higher pH prevent saturation of CaOH2? I'd imagine precipitation inside the reactor would be a major concern here as well...???

 

[Miami Reef]

Is it wise to add a calcium supplement in order to maintain the ca and kh balance?

Yes. You need to add calcium separately if using sodium hydroxide or else calcium will go out of balance.

 

[Randy Holmes-Farley Verified Community Expert]

If you start supplementing sodium hydroxide alongside calcium hydroxide to help raise pH in attempt to stay under your daily evap. Is it wise to add a calcium supplement in order to maintain the ca and kh balance?

And a tangent to this idea, is there any concern with injecting NaOH into a kalk reactor that has fully saturated CaOH2? Would the higher pH prevent saturation of CaOH2? I'd imagine precipitation inside the reactor would be a major concern here as well...???

Yes, adding sodium hydroxide will raise alk in an unbalanced way to calcium.

No, you do not want to add any calcium or hydroxide into a kalkwasser solution unless it is far below saturation because they will suppress the dissolution of calcium hydroxide.

 

[Saltyanimals]

I stumbled upon NaOH on @Randy Holmes-Farley DIY sodium hydroxide recipe as a potential alternative to kalk supplemental dosing to address pH issues for systems running CaRXs. I didn't want to thread crap too much there since the discussion was for the revised 2 part recipe. Searching stumbled on this thread.

I'm heading down this road now starting to dose sodium hydroxide. Has anyone else on this thread done this and want to share their experience?

My experience so far of 24 hour dosing is promising especially that I can continue to make a stronger solution thus less liquid to dose. I'm doing a 1.5x solution (110 g of NaOH to 1000 ml RODI) and seeing a pH boost with minimum alk rise. I could do 3x on the next solution batch and dose even less liquid. I'm keeping a log right now of my experience tracking alk and ph closely while I tune the solution and dosing.

 

[Randy Holmes-Farley Verified Community Expert]

I stumbled upon NaOH on @Randy Holmes-Farley DIY sodium hydroxide recipe as a potential alternative to kalk supplemental dosing to address pH issues for systems running CaRXs. I didn't want to thread crap too much there since the discussion was for the revised 2 part recipe. Searching stumbled on this thread.

I'm heading down this road now starting to dose sodium hydroxide. Has anyone else on this thread done this and want to share their experience?

My experience so far of 24 hour dosing is promising especially that I can continue to make a stronger solution thus less liquid to dose. I'm doing a 1.5x solution (110 g of NaOH to 1000 ml RODI) and seeing a pH boost with minimum alk rise. I could do 3x on the next solution batch and dose even less liquid. I'm keeping a log right now of my experience tracking alk and ph closely while I tune the solution and dosing.

Many people use it now, but we can wait for them to respond.

The only things to beware of are that certain types of plastic do not like high pH (such as polycarbonate) and you do want to mix the additive in quickly and potentially add it fairly slowly to prevent the local pH from getting too high and precipitating calcium carbonate (there will always be some local precipitation of magnesium hydroxide, which will redissolve as it mixes in).

 

[Saltyanimals]

Many people use it now, but we can wait for them to respond.

The only things to beware of are that certain types of plastic do not like high pH (such as polycarbonate) and you do want to mix the additive in quickly and potentially add it fairly slowly to prevent the local pH from getting too high and precipitating calcium carbonate (there will always be some local precipitation of magnesium hydroxide, which will redissolve as it mixes in).

Hi Randy. Yes I saw the polycarbonate as you warned in your DIY recipe thread. Thanks for that. I'm using a polypropylene (PP) container at a dollar store and so far so good. I did mix very slowly to keep the exothermic reaction low as possible and didn't see any issues with the container. However that's at the measurements above.

It has been said that the saturated hydroxide solution has a pH of 14.x. It never defines saturation since the solution can be made more potent. Would a 3x concentration still be 14.x ph or is that 3x the alk contribution to the water? Your thread below confirms the alk plus pH raise, but not sure about a 3x solution.



https://www.reef2reef.com/threads/r...f-the-day-171-sodium-hydroxide-dosing.231353/

 

[Randy Holmes-Farley Verified Community Expert]

Hi Randy. Yes I saw the polycarbonate as you warned in your DIY recipe thread. Thanks for that. I'm using a polypropylene (PP) container at a dollar store and so far so good. I did mix very slowly to keep the exothermic reaction low as possible and didn't see any issues with the container. However that's at the measurements above.

It has been said that the saturated hydroxide solution has a pH of 14.x. It never defines saturation since the solution can be made more potent. Would a 3x concentration still be 14.x ph or is that 3x the alk contribution to the water? Your thread below confirms the alk plus pH raise, but not sure about a 3x solution.



https://www.reef2reef.com/threads/r...f-the-day-171-sodium-hydroxide-dosing.231353/

You are unlikely to get to saturation, which has more sodium hydroxide than water.

At 40 g/L, the pH is about 14. So the pH will be between 14 and 15 (15 requires about 400 g/L, and the relationship between concentration and pH gets messed up at such high concentrations since there is not much free water around.)

 

[Miami Reef]

I only use sodium hydroxide as my alkalinity additive. I’m never going back to a different method ever.

I use sodium hydroxide for alkalinity, calcium chloride for calcium, and balling part C, for magnesium and preventing the accumulation of sodium and chloride.

 

[Saltyanimals]

You are unlikely to get to saturation, which has more sodium hydroxide than water.

At 40 g/L, the pH is about 14. So the pH will be between 14 and 15 (15 requires about 400 g/L, and the relationship between concentration and pH gets messed up at such high concentrations since there is not much free water around.)

got it. So going from 40g/L to 400g/L only yields 15 pH. That appears the pH curve starts to flatten to that 15 which I don't see myself going 4x the solution if I'm shooting for pH. That's 40 g vs 400 grams just to move up 1 pH.

Now re: Alk. I assume we are indeed multiples of alk per ml of dosing at 400 g/L. i.e. highly concentrated alk water. Following this logic, it doesn't seem to justify using a more concentrated solution if one is after pH boost without totally throwing alk through to the moon. Does that sound right?

 

[Randy Holmes-Farley Verified Community Expert]

got it. So going from 40g/L to 400g/L only yields 15 pH. That appears the pH curve starts to flatten to that 15 which I don't see myself going 4x the solution if I'm shooting for pH. That's 40 g vs 400 grams just to move up 1 pH.

Now re: Alk. I assume we are indeed multiples of alk per ml of dosing at 400 g/L. i.e. highly concentrated alk water. Following this logic, it doesn't seem to justify using a more concentrated solution if one is after pH boost without totally throwing alk through to the moon. Does that sound right?

pH is a logarithmic scale, at least in the simple definition based on H+ concentration. So every 1 pH unit rise means 10x less H+ and 10x more OH-.