Kalk vs hydroxide PH elevating boost

[Randy Holmes-Farley Verified Community Expert]

There is no advantage to using a higher concentration solution compared to any other concentration, as long as the liquid volume is easy to manage.

 

[Saltyanimals]

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-.

Interesting 10x more or less is significant.

What do you advise if one is trying to use hydroxide for pH boost? Dose more concentrated solution spread out more over 24 hours? I'm doing the experiment now, but want to see I should increase the concentration or focus on the tune the dosing amount/frequency instead. Thanks Randy!

 

[Randy Holmes-Farley Verified Community Expert]

Interesting 10x more or less is significant.

What do you advise if one is trying to use hydroxide for pH boost? Dose more concentrated solution spread out more over 24 hours? I'm doing the experiment now, but want to see I should increase the concentration or focus on the tune the dosing amount/frequency instead. Thanks Randy!

I think you might be confusing the pH of the dosing solution with the effect when it is added. Those can be different and even in different directions. For example, a bicarbonate solution at ph 8.5 will reduce the pH of seawater at pH 8.2.

Any hydroxide solution of any kind and any concentration has the same pH boost per unit of alkalinity added. Say, 1 dKH added. They all have the same pH boost no matter the concentration of the dosing solution.

The timing is a more complicated question. Add it all at once and you get a big pH spike that decays over minutes to hours as the tank pulls in CO2. 24 h later, there may be little residual effect. If you dose it nearly continuously, the spike is minimal, the there is still a small boost hours later.

Personally, I'd aim for spread out, either during the day to stabilize alk, or at night to stabilize pH, or some combination thereof.

 

[Miami Reef]

I dose my additives 24/7, just like a calcium reactor. I believe I get the best of both worlds.

I find for me, everything is more stable this way.

 

[Saltyanimals]

I dose my additives 24/7, just like a calcium reactor. I believe I get the best of both worlds.

I find for me, everything is more stable this way.

Sounds like your 3 part is working for you spread out. That’s awesome. Question on your comment about a 24/7 dose spread out. Where and when did you find your best pH boost? Ie dosing the entire daily amount over 5 hours in the dark period? Etc

 

[Miami Reef]

Sounds like your 3 part is working for you spread out. That’s awesome. Question on your comment about a 24/7 dose spread out. Where and when did you find your best pH boost? Ie dosing the entire daily amount over 5 hours in the dark period? Etc

When I said 24/7, I meant to say every hour of 24/7.

I didn’t like dosing only during the daylight because my pH went high (8.5), but night time went down to 8.1-8.2.

Now my pH ranges from 8.3 to 8.5.

Last night we had a party at home. There was cooking with the gas range, so that’s why the pH was lower than usual.

Here’s the graph for last night.

It was basically kept at 8.3.

 

[Saltyanimals]

Man I only wish my graphs would look like that. I did a dance yesterday on Day 2 of sodium hydroxide dosing because it crossed the illustrious 8.0 winner line at 8.01. Haven't seen that in a long time hence my journey down this NaOH route. I ranged 7.5-7.9. Now 7.6-8.0. Gives me about a 0.1 pH boost to my range. Not significant, but I would love to be able to squeeze out another 0.1 by trying to tune the solution or dosing times.

Randy highlight an interesting point about the ph effect vs the pH of the solution. I was thinking exactly that example that I should get pH increase logically by introducing higher pH solution to the water. i.e. CaRx effluent introducing a very low pH water into the tank draging down the overall pH. Bicarbonate solution example that Randy called out is the opposite effect.

So appears the pH effect is what I'm after. If introducing any concentration has the same effect to the tank at 1x or 4x the concentration...then there is no need to make a stronger solution. It's better to make a weaker one with less alk to affect the tuning of the CaRx.

I'm dosing NaOH every 30 mins right now, but may experiment with a nighttime only dosing to keep the bottom of that pH range up during the dark period. Maybe it'll even drive the top end higher because it has "less to climb".

You brought up an interesting point that I never thought about: gas range. Makes sense when I think about it and we cook daily with gas ranges in our home. That's another Co2 contributor added to my list: CaRx, biopellets, large fish count, sealed home, more people at home, etc.

 

[Dburr1014]

Man I only wish my graphs would look like that. I did a dance yesterday on Day 2 of sodium hydroxide dosing because it crossed the illustrious 8.0 winner line at 8.01. Haven't seen that in a long time hence my journey down this NaOH route. I ranged 7.5-7.9. Now 7.6-8.0. Gives me about a 0.1 pH boost to my range. Not significant, but I would love to be able to squeeze out another 0.1 by trying to tune the solution or dosing times.

Randy highlight an interesting point about the ph effect vs the pH of the solution. I was thinking exactly that example that I should get pH increase logically by introducing higher pH solution to the water. i.e. CaRx effluent introducing a very low pH water into the tank draging down the overall pH. Bicarbonate solution example that Randy called out is the opposite effect.

So appears the pH effect is what I'm after. If introducing any concentration has the same effect to the tank at 1x or 4x the concentration...then there is no need to make a stronger solution. It's better to make a weaker one with less alk to affect the tuning of the CaRx.

I'm dosing NaOH every 30 mins right now, but may experiment with a nighttime only dosing to keep the bottom of that pH range up during the dark period. Maybe it'll even drive the top end higher because it has "less to climb".

You brought up an interesting point that I never thought about: gas range. Makes sense when I think about it and we cook daily with gas ranges in our home. That's another Co2 contributor added to my list: CaRx, biopellets, large fish count, sealed home, more people at home, etc.

Please report back after a couple days experimenting. If love to hear your thoughts.

My carx drives my pH 7.8/7.9, not horrible at all. My alk climbed to 10 over the past week so I shut off the co2 to get the alk down to 8 where my system normally runs and the ph hit 8.1 yesterday. I do run Kalk 24/7.
Thinking about switching over, just not ready yet. More reading needed and pros/cons to figure out.

 

[mudbugmike]

I’ve used sodium hydroxide along with the exact same other products as @Miami Reef . Been using 5 or so months now and won’t swap unless conditions change significantly .

Without co2 scrubbing my ph is down to 7.75 or so. I dose 1ml/hr of the hydroxide solution daily. I aim for <= 10 dkh. I’ve thought about pushing this up to 11 to help my ph further but I believe I would be approaching danger they. I also open the doors. Ph climbs to nearly 8.3.

I get a bit jealous when I see people sitting at 8.4-8.5 all day. Co2 buildup is something I’d never have considered if not for my saltwater tank. There are days with scrubbing I’m lucky to be over 8ph.

I have a 1700sq ft home with a wife, kid, and 2 dogs. I’ve kindly asked them to limit their co2 creation.

 

[ChuckTownReefer]

You can always mix sodium hydroxide in with your kalkwasser to help boost ph. I have been doing it for a while. Then you don't have to really worry about calcium and alkalinity. Because once you boost your ph calcium and alkalinity will drop fast and fast.

 

[Randy Holmes-Farley Verified Community Expert]

You can always mix sodium hydroxide in with your kalkwasser to help boost ph. I have been doing it for a while. Then you don't have to really worry about calcium and alkalinity. Because once you boost your ph calcium and alkalinity will drop fast and fast.

I don't recommend that mixing because the presence of a lot of hydroxide from sodium hydroxde will prevent the calcium hydroxide from dissolving. In a sense it is just the sodium hydroxide with a tiny bit of calcium added.

 

[Dburr1014]

I’ve used sodium hydroxide along with the exact same other products as @Miami Reef . Been using 5 or so months now and won’t swap unless conditions change significantly .

Without co2 scrubbing my ph is down to 7.75 or so. I dose 1ml/hr of the hydroxide solution daily. I aim for <= 10 dkh. I’ve thought about pushing this up to 11 to help my ph further but I believe I would be approaching danger they. I also open the doors. Ph climbs to nearly 8.3.

I get a bit jealous when I see people sitting at 8.4-8.5 all day. Co2 buildup is something I’d never have considered if not for my saltwater tank. There are days with scrubbing I’m lucky to be over 8ph.

I have a 1700sq ft home with a wife, kid, and 2 dogs. I’ve kindly asked them to limit their co2 creation.

I'm also in a 1700 sqf home. Me my wife and a small dog. My wife's son and daughter have been also staying with us for a few months now. They are moving out Tuesday.
I bought a co2 monitor with a ndir sensor to check co2 levels in the house. TBH, they don't look bad. I calibrated it outside, the basement sump area is about 650, tank area is about 750 until people get home. Then it goes up to >850. Which still isn't horrible. So I'm pretty sure it's the Carx driving the ph down.
I don't have a scrubber don't want one. My air for the skimmer comes from outside.

 

[Saltyanimals]

I’ve used sodium hydroxide along with the exact same other products as @Miami Reef . Been using 5 or so months now and won’t swap unless conditions change significantly .

Without co2 scrubbing my ph is down to 7.75 or so. I dose 1ml/hr of the hydroxide solution daily. I aim for <= 10 dkh. I’ve thought about pushing this up to 11 to help my ph further but I believe I would be approaching danger they. I also open the doors. Ph climbs to nearly 8.3.

I get a bit jealous when I see people sitting at 8.4-8.5 all day. Co2 buildup is something I’d never have considered if not for my saltwater tank. There are days with scrubbing I’m lucky to be over 8ph.

I have a 1700sq ft home with a wife, kid, and 2 dogs. I’ve kindly asked them to limit their co2 creation.

@mudbugmike @Miami Reef Appears to have the traditional 3 part using the NaOH for the alk part. They're likely in a better starting place from a pH perspective unlike the CaRX users. I used to be a 3 part-er, but got tired of mixing parts to support a 180g. The CaRX was a great idea for the lazy I-don't-like-to-mix reefer like myself. It was great until I realized the pH draw back. Then I went down a biopellet route to solve nutrients. Mission accomplish there, but little did I know biopellets further drags down pH. And Co2 scrubbers suck for the effort and $$$ for very little gains.

This experiment is to find a solution that I don't have to abandon the CaRX if I can have a tuned solution that provides the boost. Tuned = low liquid and less impactful to the existing tuned system. I expect to turn my CaRX down a tad bit since I'm getting the additional alk from the NaOH. My happy place here is to be able to dose 15-20ml daily to solve the pH which means maybe mixing the solution every 2-3 months. Kalk slurry seems to be another viable alterative if this NaOH doesn't work out.

I'll definitely share my experiences over the next several weeks of this experiment.

 

[Miami Reef]

I used to be a 3 part-er, but got tired of mixing parts to support a 180g.

My tank is 260 gallons.

I actually find it very fun to mix up my solutions. Especially with my magnetic stirrer.

 

[mudbugmike]

My tank is 260 gallons.

I actually find it very fun to mix up my solutions. Especially with my magnetic stirrer.

Which stirrer do you use? I only mix up a gallon at a time but the cheap one off amazon couldn't handle the weight.

 

[Miami Reef]

Which stirrer do you use? I only mix up a gallon at a time but the cheap one off amazon couldn't handle the weight.

I also mix up a gallon at a time.

This is the exact one I use and it works perfectly! If you use this same one, I can maybe help you figure it out!

https://a.co/d/6Ks32PX

 

[mudbugmike]

I also mix up a gallon at a time.

This is the exact one I use and it works perfectly! If you use this same one, I can maybe help you figure it out!

https://a.co/d/6Ks32PX

oh dang that's exactly what I had. The weight of the water would push down on the top and stop the spinning. Eventually it got to the point where the magnetic pill wouldn't spin with anything there and returned it. Maybe I'll give it another shot because when it worked it sure was luxurious.

 

[Miami Reef]

oh dang that's exactly what I had. The weight of the water would push down on the top and stop the spinning. Eventually it got to the point where the magnetic pill wouldn't spin with anything there and returned it. Maybe I'll give it another shot because when it worked it sure was luxurious.

I haven’t had this experience. Maybe a higher quality one would be better?

I use vinegar HDPE bottles to mix my solutions in.

 

[Saltyanimals]

As promised, I'm reporting back. I tested alk 2x daily at same time +/- 10 mins and took note of the corresponding pH at the reading. I did this and kept a testing log over the last 10 days using 2 test scenarios:

1) Dosing hourly*
2) Dosing every 30 mins*

*Per a given total daily dose of 24ml which is estimated to provide an additional 0.5 dKh.

Observed:
- General pH raise in my low-high range of approx. 0.15. Previous range: 7.55 to 7.85. New range: 7.7 to 8.0
- pH stability wasn't seen as any real difference between dosing hourly vs every 30 mins.
- Overall tank alk didn't seem to change which was my intention dosing such as small additional 0.5 dKh since my CaRx continue to run.


Conclusion:

This is only a 10 day test so not long enough to report any real data to bet the farm on. The pH boost was welcomed since I haven't crossed the 8.0 in a very long time. However was not in line with the expected 0.6-0.8 pH boost for every 1 dKh added notion I read somewhere on hydroxide dosing. I think this is because I'm dosing such a small liquid amount of 1 ml every hour to a 180g system. Since my goal is to continue to dose less NaOH liquid, I think the logical move is to increase the potency of NaOH solution providing more "dkH per ml". I'm dosing a 73.5g/L strength solution. Will double that now to 147g/L strength.

Next Steps:

Make new batch of 3x solution and continue the same dose schedule 1ml/hour for a total 24 ml/daily. I would now expect my new daily dKh contributor in this new solution to be approaching 1.0dkH hoping to get my pH boost closer to that desirable 0.6-0.8 boost. I will continue to test 2x alk daily. If the projection is correct, I should start seeing a Alk raise which I'll throttle down my CaRX to keep my parameter flat.

Question/Help

Can someone help double check my solution recipe? Does 147 grams to 1000 ml = 3x solution providing 1 dKH per ML?


Thanks

 

[Randy Holmes-Farley Verified Community Expert]

This is only a 10 day test so not long enough to report any real data to bet the farm on. The pH boost was welcomed since I haven't crossed the 8.0 in a very long time. However was not in line with the expected 0.6-0.8 pH boost for every 1 dKh added notion I read somewhere on hydroxide dosing.

I think it is in line with expectations, or at least not lower than expected. I'm actually surprised your rise is as much as it is.

In the article below, I show that adding 0.5 meq/L (1.4 dKH) all at once boosts the pH in new instant Ocean from 8.10 to 8.76, for a rise of 0.66 pH units. You added ~1/3 as much, and spread it out over 24 h, so the pH will never rise as much since the tank can pull in CO2 after every addition.

In my case, over 24 h of aeration in a beaker, the pH dropped back to 8.31 and was completely independent of whether I had initially boosted alk with baking soda, washing soda/sodium carbonate, or sodium hydroxide. All end up at the same pH, as expected.

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

Randy answers many questions in this complex relationship.

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