Neptune Aquatics

Alk - Soda ash dosing?

Bolicks

Bolicks

Supporting Member
BARcard
Just received a doser and soda ash to increase my alk, since it drops from 8-7.8 dkH (right after W.C.) to 7 dKH 6-7 days post W.C. . pH consistently tests at 8-8.2. Calcium consistently tests at 1400-1500, so it seems that I need to solely elevate my alkalinity.

Seems like an eventual Alk target of 8-9 is ideal - How incrementally should I increase alkalinity via soda ash dosing, without raising pH excessively? Does it make more sense to dose soda ash or kalkwasser to raise Alkalinity in this case?

Appreciate help and any tips!
 
Bolicks said:
Just received a doser and soda ash to increase my alk, since it drops from 8-7.8 dkH (right after W.C.) to 7 dKH 6-7 days post W.C. . pH consistently tests at 8-8.2. Calcium consistently tests at 1400-1500, so it seems that I need to solely elevate my alkalinity.

Seems like an eventual Alk target of 8-9 is ideal - How incrementally should I increase alkalinity via soda ash dosing, without raising pH excessively? Does it make more sense to dose soda ash or kalkwasser to raise Alkalinity in this case?

Appreciate help and any tips!
Click to expand...
Do you mean magnesium is 1400? I started playing with 10 ml/day increments to get close, then tune the last 5 ml/day when I am at the numbers I want. I wouldn't worry too much about ph as you have it in a good place, and it is unlikely you will push it too high with your dosing.
 
I think to keep alk higher, you need to use baking soda/sodium bi-carbonate.
Soda ash is my understanding, to bring pH up to a desired point.
My mind is a bit dusty but some others will chime in.
 
xcaret said:
I think to keep alk higher, you need to use baking soda/sodium bi-carbonate.
Soda ash is my understanding, to bring pH up to a desired point.
My mind is a bit dusty but some others will chime in.
Click to expand...
Soda ash (sodium carbonate) and baking soda (sodium bicarbonate) both raise alkalinity. Soda ash will also raise ph, and that is usually a good thing.
 
H2OPlayar said:
Do you mean magnesium is 1400? I started playing with 10 ml/day increments to get close, then tune the last 5 ml/day when I am at the numbers I want. I wouldn't worry too much about ph as you have it in a good place, and it is unlikely you will push it too high with your dosing.
Click to expand...
Whoops, that's right. Calcium is 450-500. Awesome, will give a similar regiment a shot. What concentration do you mix your soda ash to? Mine is dry.
 
Assuming you're using the BRS soda ash, you can go here: https://www.bulkreefsupply.com/reef-calculator and calculate the amount it takes to raise your alkalinity by 0.1. You can use that as a guideline to proceed. You can also read the instructions at the bottom to learn more about the pH effect.

Screenshot_2021-05-13_21-40-05.png
 
guys i'm a rusty old fuck but am i right that the different pka of sodium bicarb will only allow a ph of like 7.8 as opposed to soda ash ?
where's ian or mikey on this one ? :D and aren't we still just doing kalk to only bring up ph ? damn i'm out of the game son
 
aquaticcentral said:
guys i'm a rusty old fuck but am i right that the different pka of sodium bicarb will only allow a ph of like 7.8 as opposed to soda ash ?
where's ian or mikey on this one ? :D and aren't we still just doing kalk to only bring up ph ? damn i'm out of the game son
Click to expand...

You are correct in theory, I don't know about exact numbers, but that makes sense. I run soda ash and get pH from 7.8 to 8.2, so I would assume if I ran sodium bicarbonate instead, I wouldn't get the pH elevation benefit and likely peak at 7.8
 
That is my understanding about soda ash and baking soda.
I followed the recipes from Randy Holmes Farley.
And as usual, lime/kalk does wonders for pH but it might as well do harm if too much/too fast is added.
 
aquaticcentral said:
guys i'm a rusty old fuck but am i right that the different pka of sodium bicarb will only allow a ph of like 7.8 as opposed to soda ash ?
where's ian or mikey on this one ? :D and aren't we still just doing kalk to only bring up ph ? damn i'm out of the game son
Click to expand...

PH is a function of Alkalinity ... when CO2 levels are in equilibrium with atmosphere.

So if you add Alk, PH goes up.
As corals use up Alk, PH goes down.
This drives the base level.
It is curve, not linear.

But that last part also matters.
When there is excess CO2, PH goes down.
When there is a lack of CO2, PH goes up.
This is why there are temporary swings during the day.

As far as the whole Baking Soda / Soda ash thing.
It is complex, something to do with being amphiprotic base/acid. I don't get it, maybe someone else does.

http://www.reefkeeping.com/issues/2004-05/rhf/
 
Na2CO3 is a stronger base than NaHCO3. In aqueous solution, Na2CO3 is di-protic and dissociates into CO3 - - while NaHCO3 is mono-photic and dissociates into HCO3 - . Hence, Na2CO3 will raise pH more than NaHCO3.
 
Also you will likely find that you need to dose Ca as well when you start dosing Alk. That’s why it’s called 2-part.

When you keep the Alk at a higher level more consistently, you will drive more usage of Ca and probably will have it drop too much for your water changes to be able to keep it in the normal range.

At your relative low uptake rate you probably will not have to dose Mg.

As far as the pH issue you asked about, adding too much soda ash at once is much more dangerous because of the spike in Alk than the spike in pH. So if you are keeping the Alk changes in recommended limits the pH change should be fine.

Also the differential pH effect of the 2 options for raising Alk are temporary (as it equilibrates with air CO2). If you dose continuously you’ll have a continuous effect, but not a huge one.
 
Back when I spiked my alk (with soda ash) the pH rose .64 while the Alk rose 3.85, so you’re probably going to be limited by how much you can raise the alk per day (maybe .5 - 1dKh) , not the pH, since as @JVU said most of the pH effect will equilibriate over the timeline of a day.
 
Wlachnit said:
Na2CO3 is a stronger base than NaHCO3. In aqueous solution, Na2CO3 is di-protic and dissociates into CO3 - - while NaHCO3 is mono-photic and dissociates into HCO3 - . Hence, Na2CO3 will raise pH more than NaHCO3.
Click to expand...
not sure what you said here :D but sounds like you were somewhat agreeing with me ? but then again i took spanish in highschool, not greek
 
You must log in or register to reply here.
Back
Top