Sodium Bisulfate to Reduce Alkalinity in New Salt Water or in Display Tanks

[TMC1313]

I've been using this product for two years now with no issues at all. I started using seachem acid buffer because I like to keep lower alkalinity (7.0-7.3) and I like to use the red sea salt mix (blue bucket) that mixes up around 8.0.
Thread 'Home Depot pool muriatic acid' https://www.reef2reef.com/threads/home-depot-pool-muriatic-acid.549596/

 

[Jeff Hollabaugh]

I just want to record these calculations in their own thread to refer back to in other threads.

When alkalinity is too high in new salt water or in a display tank, acid can be used to lower the alkalinity. You can easily use muriatic acid (hydrochloric acid), or sodium bifulfate (e.g., Seachem Acid Buffer is this chemical, I think) or sulfuric acid (but that one is harder to get for hobbyists).

Note that these methods reduce pH a lot (and to the same extent), until you aerate adequately, so go very slow in a display and aerate a lot to drive off the excess CO2 that is generated.

Dropping alk by 1.4 dKH when starting at 6.3 dKH will drop pH below 7 (I got 6.9, experimentally). The effect is roughly linear with alkalinity, so starting at 12.6 dKH, a drop of 2.8 dKH will drop the pH to around 7 or a bit lower (depends on the starting pH, of course).

Sodium bisulfate is NaHSO4.

In seawater, it releases H+:

NaHSO4 ---> Na+ + H+ + SO4--

The H+ is what reduces the alkalinity, and the Na+ and SO4-- are not any concern:

H+ + CO3-- --> HCO3-

So, how much is needed?

NaHSO4 weighs 120.1 grams per mole. Thus, 120.1 grams has the potential to reduce alkalinity by 1 mole, or 1 equivalent, or 1000 meq (milliequivalents).

If you were to add that much to 1000 L, you would drop the alkalinity by 1000 meq/1000L = 1 meq/L = 2.8 dKH.

So 1.2 grams per 10 Liters, drops alkalinity by 2.8 dKH.

If you do not have a scale, we can roughly estimate how much is in a teaspoon:

1 cubic centimeter (1 mL dry) weighs roughly 1.44 grams.

A level teaspoon (4.93 mL) will then weigh roughly 7.1 grams.

1 level dry teaspoon of sodium bisulfate added per 100 L of tank water will drop the alkalinity by about 1.7 dKH.

Dissolve it in fresh water before adding it slowly to a high flow area.

DO NOT USE BISULFITE. Note the "i" in the ending vs an "a"

These materials should be fine to use:

Well just received the

Sodium Bisulfate and tried it so far it has just made my ph go way down How long should it take to lower alk​

 

[Jeff Hollabaugh]

I've been using this product for two years now with no issues at all. I started using seachem acid buffer because I like to keep lower alkalinity (7.0-7.3) and I like to use the red sea salt mix (blue bucket) that mixes up around 8.0.
Thread 'Home Depot pool muriatic acid' https://www.reef2reef.com/threads/home-depot-pool-muriatic-acid.549596/

Hi i just started using the sodium bisulfate to lower my alk any idea how long it will take to accomplish alk lowering so far it has just made my ph plunge i have been using 1tsp for 100 l of tank water

 

[Randy Holmes-Farley]

Well just received the

Sodium Bisulfate and tried it so far it has just made my ph go way down How long should it take to lower alk​

It lowered both alk and pH instantly.

The pH effect is large, and I usually only recommend it for new water, or use it VERY slowly for that reason.

 

[Jeff Hollabaugh]

Got ya Thanks

 

[chipchipbro]

if my DT tests at 10.5 Dkh and I want to bring it down.. can I just mix new saltwater with a very low Dkh (using sodium bisulfate) to come down to 8 dkh in the DT?

If yes, how fast and how would you calculate it in a 200 litre tank @Randy Holmes-Farley ?

 

[Randy Holmes-Farley]

if my DT tests at 10.5 Dkh and I want to bring it down.. can I just mix new saltwater with a very low Dkh (using sodium bisulfate) to come down to 8 dkh in the DT?

If yes, how fast and how would you calculate it in a 200 litre tank @Randy Holmes-Farley ?

Yes, but good aeration of the new salt water is needed to blow off the excess CO2.

The alk of a mix is the weighted average of the alk of the two solutions. For a 50% change, it’s just the average of the two alk values.

 

[jduong916]

I just want to record these calculations in their own thread to refer back to in other threads.

When alkalinity is too high in new salt water or in a display tank, acid can be used to lower the alkalinity. You can easily use muriatic acid (hydrochloric acid), or sodium bifulfate (e.g., Seachem Acid Buffer is this chemical, I think) or sulfuric acid (but that one is harder to get for hobbyists).

Note that these methods reduce pH a lot (and to the same extent), until you aerate adequately, so go very slow in a display and aerate a lot to drive off the excess CO2 that is generated.

Dropping alk by 1.4 dKH when starting at 6.3 dKH will drop pH below 7 (I got 6.9, experimentally). The effect is roughly linear with alkalinity, so starting at 12.6 dKH, a drop of 2.8 dKH will drop the pH to around 7 or a bit lower (depends on the starting pH, of course).

Sodium bisulfate is NaHSO4.

In seawater, it releases H+:

NaHSO4 ---> Na+ + H+ + SO4--

The H+ is what reduces the alkalinity, and the Na+ and SO4-- are not any concern:

H+ + CO3-- --> HCO3-

So, how much is needed?

NaHSO4 weighs 120.1 grams per mole. Thus, 120.1 grams has the potential to reduce alkalinity by 1 mole, or 1 equivalent, or 1000 meq (milliequivalents).

If you were to add that much to 1000 L, you would drop the alkalinity by 1000 meq/1000L = 1 meq/L = 2.8 dKH.

So 1.2 grams per 10 Liters, drops alkalinity by 2.8 dKH.

If you do not have a scale, we can roughly estimate how much is in a teaspoon:

1 cubic centimeter (1 mL dry) weighs roughly 1.44 grams.

A level teaspoon (4.93 mL) will then weigh roughly 7.1 grams.

1 level dry teaspoon of sodium bisulfate added per 100 L of tank water will drop the alkalinity by about 1.7 dKH.

Dissolve it in fresh water before adding it slowly to a high flow area.

DO NOT USE BISULFITE. Note the "i" in the ending vs an "a"

These materials should be fine to use:

Is it ok to add the Sodium Bisulfate to already mixed NSW, in its holding container?

This is what I plan to do, just wanted to run it by you.

1) Add 40 gallons of RODI to my mixing container
2) Turn on recirculating pump (grabs water from bottom and dumps it back on top, splashing the surface)
2) Add salt
3) Add Seachem Acid buffer (20 grams to lower 3 dkh)
4) Let this mix for at least a day with the container lid off. Mix longer if needed to raise PH.

Do you see anything wrong with this? Thanks in advance.

 

[Randy Holmes-Farley]

Is it ok to add the Sodium Bisulfate to already mixed NSW, in its holding container?

This is what I plan to do, just wanted to run it by you.

1) Add 40 gallons of RODI to my mixing container
2) Turn on recirculating pump (grabs water from bottom and dumps it back on top, splashing the surface)
2) Add salt
3) Add Seachem Acid buffer (20 grams to lower 3 dkh)
4) Let this mix for at least a day with the container lid off. Mix longer if needed to raise PH.

Do you see anything wrong with this? Thanks in advance.

That’s the right plan!

 

[editour2]

To treat a system that has a total system volume of 340 gals you would use approximately: 13 teaspoons or 90 grams to lower the alkalinity by 1.7 dkh. The whole 4 ounce container by Loudwolf only has 113 grams and costs $14 plus $6 shipping. That product is 99.5% sodium bisulfate.
I just saw this product from Doheny's :

Doheny's pH Minus - Doheny's Pool Supplies Fast

Looking for Doheny's pH Minus? We have this and more, in stock and at the lowest price.

www.doheny.com

Which sells 5 pounds for $25.49, (don't know what shipping costs). This product is 95% Sodium Bisulfate.

 

[Randy Holmes-Farley]

To treat a system that has a total system volume of 340 gals you would use approximately: 13 teaspoons or 90 grams to lower the alkalinity by 1.7 dkh. The whole 4 ounce container by Loudwolf only has 113 grams and costs $14 plus $6 shipping. That product is 99.5% sodium bisulfate.
I just saw this product from Doheny's :

Doheny's pH Minus - Doheny's Pool Supplies Fast

Looking for Doheny's pH Minus? We have this and more, in stock and at the lowest price.

www.doheny.com

Which sells 5 pounds for $25.49, (don't know what shipping costs). This product is 95% Sodium Bisulfate.

My concern is what the impurities in it may be.

 

[editour2]

Ok...that was my worry as well. Anywhere I can get more product than 4 ounces for a better price? My DT, (total system volume is around 340 gals), has always run at around 7.5dkh...for the last few weeks my coral polyp extension has been closing up. My purple stylo which I've had for 12 years looks like it's near death. I measured alkalinity and it was over 12 which really shocked me. I've been doing 25 gallon water changes daily, 4 days in a row, with reef crystals salt but it doesn't seem to be making a dent. I just received my order of 4 ounces of Loudwolf sodium bisulfate. I want to go slowly because nothing good can come from Quick change. Funny but I measured my water change water and the reef crystals salt was around 7 after 24 hours mixing, (even though I've read reef crystals has high alkalinity). I'm going to retest with a 2nd brand test kit and confirm results.

 

[editour2]

Just used my Hanna Colorimeter to measure Alkalinity and got a reading of 300ppm or 16.8 dkh....that's crazy. I tested my RODI water and that measured zero so I'm really confused. Measured my ATO water which I add Kalkwasser to keep the ph up and that also Measured 300ppm. Lastly just saw reagent for my Hanna meter had an exp date of Dec 2020. What a mess !!!

 

[Browser]

I am in my 5th month of my new reef tank.
My scape is done with Aquaforest dry rock and i have sand substrate from Caribsea Arag alive.

I believe something is desolving cause my alkalinity keeps rising, with slow rate. I am now at 9.8. To understand the rate, last two weeks raised form 9.54 to 9.8 steadily.

I measure with Hanna, salifert and Trident.
I add nothing yet to the tank. I use Tropic marine pro for salt which give me 7.6 alkalinity.
I make daily water changes of 5 liters.

Since i will start to introduce corals to the tank, i would like to drop the alkalinity to 7.6->8.0
My PH swings from 7.9->8.1 with the CO2scrubber.
To day i put a hose to draw air from outside so i do not know the effects on that yet.
I also use ozon through silica dryer controled to 350 ORP.
My PH swings from 7.9->8.05.

I bought Seachem Acid Buffer to do that, and i would like to do it though my auto top off or a dose pump.
Total water volume is 600lt.

@Randy Holmes-Farley , can you please propose me the best way to do it ? I would appreciate also some dosage help with seachem acid buffer because i do not know the exact concertation of sodium bisulfate in it.

Thank you in advance

 

[Browser]

From seachem directions :

"To lower pH, use 1/4 teaspoon (2g) for every 80 L (20 US gallons) daily until desired pH is reached (this dose lowers alkalinity by about 0.2 meq/L (0.6 dKH)). Larger doses may be required in very hard (KH) or alkaline waters"

That means that in my case if i dilute 15gr of acid buffer and dose it in my tank , this will drop my alk by 0.6 ?
Am i getting this right ?

 

[editour2]

After purchasing new reagents for my Red Sea and Hanna testers I feel more confident in the readings I'm getting on my tests. After about 3 weeks of every other day water changes, (adding sodium bisulfate to my 30 gal water change water), my total system water (approximately 330 gals) is around 8dkh. I switched my salt from reef crystals to Fritz blue box because the box says the alkalinity mixes to around 8 to 9 however mine has been mixing lower. My purple stylo is back and so is my jack o lantern chalice which had lost alot of its color. I test Alkalinity on my DT water, my saltwater change water and my ATO water every 3 or 4 days now and make slight adjustments to maintain alkalinity at this level. Believe it or not I've been adjusting the alkalinity up on my ATO and water change water because if not my alkalinity drops to around 7 dkh.....

 

[Randy Holmes-Farley]

From seachem directions :

"To lower pH, use 1/4 teaspoon (2g) for every 80 L (20 US gallons) daily until desired pH is reached (this dose lowers alkalinity by about 0.2 meq/L (0.6 dKH)). Larger doses may be required in very hard (KH) or alkaline waters"

That means that in my case if i dilute 15gr of acid buffer and dose it in my tank , this will drop my alk by 0.6 ?
Am i getting this right ?

I would not go by Seachem's directions, but by those on page 1 of this thread.

1 level dry teaspoon of sodium bisulfate added per 100 L of tank water will drop the alkalinity by about 1.7 dKH.

Dissolve it in fresh water before adding it slowly to a high flow area.

FWIW, your alk rise is small and slow, so may be from dissolving sand, or from declining nitrate.

 

[Randy Holmes-Farley]

After purchasing new reagents for my Red Sea and Hanna testers I feel more confident in the readings I'm getting on my tests. After about 3 weeks of every other day water changes, (adding sodium bisulfate to my 30 gal water change water), my total system water (approximately 330 gals) is around 8dkh. I switched my salt from reef crystals to Fritz blue box because the box says the alkalinity mixes to around 8 to 9 however mine has been mixing lower. My purple stylo is back and so is my jack o lantern chalice which had lost alot of its color. I test Alkalinity on my DT water, my saltwater change water and my ATO water every 3 or 4 days now and make slight adjustments to maintain alkalinity at this level. Believe it or not I've been adjusting the alkalinity up on my ATO and water change water because if not my alkalinity drops to around 7 dkh.....

Glad things are looking better.

 

[Browser]

I would not go by Seachem's directions, but by those on page 1 of this thread.

1 level dry teaspoon of sodium bisulfate added per 100 L of tank water will drop the alkalinity by about 1.7 dKH.

Dissolve it in fresh water before adding it slowly to a high flow area.

FWIW, your alk rise is small and slow, so may be from dissolving sand, or from declining nitrate.

Thank you.

How about the rate for reducing the alk? Let's say the target is to drop kh by 2 dkh and I calculate the sodium bisulfate needed, should I dose it in one day time or longer?

 

[Randy Holmes-Farley]

Thank you.

How about the rate for reducing the alk? Let's say the target is to drop kh by 2 dkh and I calculate the sodium bisulfate needed, should I dose it in one day time or longer?

Are you talking about dropping the alk in water change water (no limit) or in an aquarium (go very slow due to the big pH drop)? I recommend the water change route.