Attributes of an improved two part?

[Randy Holmes-Farley]

The alkalinity part of two part additive system can generally be formulated with bicarbonate and/or carbonate. Bicarbonate gives a slight pH lowering effect and carbonate gives a pH boost, and any mixture of them can be used to get any desired pH effect in between.

But those are not the only choices. Hydroxide can also be used, and food grade sodium hydroxide is inexpensive. The pH boost is quite a bit higher than for carbonate (about 2x), and the concentration can be made much higher since it is much more soluble than sodium bicarbonate or carbonate.

For manual dosing, such a product might not be a good choice with too rapid of a big pH boost.

Today, however, dosing pumps have become so pervasive that such a product can easily be used and could have substantial benefits over existing two parts.

Additionally, I think any current manufacturer of two part systems could likely swap out the carbonate and bicarbonate and swap in hydroxides with no reformulation needed (stressing "I think"). So your favorite company could easily come out with a new version, and the new versions could be made more concentrated, if desired (at the least, there'd be less cost to ship less water).

 

[rushbattle]

Thank you for posting this Dr. H-F. I have been wondering about sodium hydroxide substitute for sodium carbonate for CO2 reduction. It seems as though it would need to be dosed in very small quantities, many times over the whole day.

 

[Randy Holmes-Farley]

Thank you for posting this Dr. H-F. I have been wondering about sodium hydroxide substitute for sodium carbonate for CO2 reduction. It seems as though it would need to be dosed in very small quantities, many times over the whole day.

Yes, which is why the only major use of hydroxide previously was dosing limewater/kalkwasser on slow dose pump or ATO.

 

[rushbattle]

Yes, which is why the only major use of hydroxide previously was dosing limewater/kalkwasser on slow dose pump or ATO.

I am sorry, I'm taking the lazy way out and asking you, but do you have a feel for how many times a day it would need to be spread out evenly to avoid excessive pH spikes at each dose? Maybe a number of times for a high demand tank and a medium demand tank?

 

[JimWelsh]

Wouldn't exposure of a NaOH solution to atmospheric CO2 cause the pH to drop over time, turning it essentially into a NaHCO3 solution? Is there a way to calculate the rate at which this occurs? Also, assuming an unlimited supply of air with a concentration, say, of 400 PPM CO2, is there a point at which this process would reach equilibrium? For that matter, does your original improved 2-part sodium carbonate solution suffer the same pH-lowering effect over time, becoming a mixture of bicarbonate and carbonate?

 

[Randy Holmes-Farley]

Wouldn't exposure of a NaOH solution to atmospheric CO2 cause the pH to drop over time, turning it essentially into a NaHCO3 solution? Is there a way to calculate the rate at which this occurs? Also, assuming an unlimited supply of air with a concentration, say, of 400 PPM CO2, is there a point at which this process would reach equilibrium? For that matter, does your original improved 2-part sodium carbonate solution suffer the same pH-lowering effect over time, becoming a mixture of bicarbonate and carbonate?

Yes, leaving it open to the air will lower the pH of both this version and a sodium carbonate version of a two part.

Let's do a thought experiment. Let's say you have a gallon bottle of a two part that is 3x as concentrated as my DIY recipe #1 (1.9 eq/L), so a concentration of 3 x 1.9 m = 5.7 M NaOH. That one gallon contains 21.6 moles of hydroxide.

If you wanted to convert that all to the equivalent of the carbonate recipe, you'd need to add 21.6 moles of carbon dioxide.

How much air is that?

At 400 ppm CO2 in air, and 1 mole occupying about 22.4 L, that's 21.6 x 1,000,000/400 x 22.4 l = 1.2 million liters of air.

So you'd need to pass 1.2 million liters of air through the container, and have all of the CO2 stripped out of that air.

Seems like something a simple lid can control.

 

[Randy Holmes-Farley]

I am sorry, I'm taking the lazy way out and asking you, but do you have a feel for how many times a day it would need to be spread out evenly to avoid excessive pH spikes at each dose? Maybe a number of times for a high demand tank and a medium demand tank?

Depends on how much alkalinity you need to deliver. Adding 1.4 dKH at once boosts pH in marine aquarium water by very roughly 0.65 pH units. 1/10th of that is OK if you mix it in fast enough so local effects are not an issue.

 

[GoVols]

Randy,
I maybe be off base but I personally would not adjust (mod) the products that I use.
Over the past year, I've become a window opening junkie and (lol)... Have no need to test ph anymore.

Getting the trapped in CO2 out and fresh air, with the the outdoor atmosphere in, has really made a different in my reef.
I can't prove it but bringing outdoor atmosphere in, could be making a difference with all the other types on ions that are in the outdoor atmosphere, but I'm not a scientist and I could be totally in left field ;Wacky

Anyway,
If our central heat and air, bites the dust for good and we have to purchase a new unit.
Then a built in EVR will be under heavy consideration.

Over the long haul, they are suppose to be more energy efficient over a one year period of time.
They do release out old air and bring in the fresh air.
For things that are more efficient, you usually get tax breaks or other incentives to help make that move.

Thanks for the thread.

Regards, GoVols

 

[saltyhog]

Do you think dosing pumps are consistent enough to make more concentrated solutions ok? I currently dose alk every hour at the top of the hour and calcium at the bottom of the hour. I dose more alk during the night when pH is lower than in the daytime (using soda ash-carbonate)

It would be nice to not have to fill my dosing containers as often.

 

[Bouncingsoul39]

I'm lucky to live in Southern California and have windows open daily throughout the year. My tank stays a steady 8.2-8.3 with the fuge running on a reverse photo-period. For my personal needs, I would like a more concentrated product just for the aspect of it being a better value.

 

[redfishbluefish]

I think part of my reasoning for no change is that I'm an old fart and don't like change.....leave it be.

However, the one concern I have with a more potent alkalinity part is that an oh-so-slight miscalculation or overdosing or underdosing results in larger swings in alkalinity. I believe folks are very poor testers....not testing frequently enough to catch these swings. With less potent additives, safer for those of use who test infrequently.

 

[BoomCorals]

This is of great interest to me as I am actually looking to move away from a kalk ato solution and use instead a dos pump for calcium and alk. I would welcome the increased PH boost from the hydroxide. So I'm guessing I could use calcium hydroxide and sodium hydroxide in separate containers for my calcium and alk dosing? Where can I find information on dos increments, and how much to mix etc?

 

[Mindi]

Randy...I cant open windows and am subject to ongoing CO2 laden air, and running an expensive CO2 scrubber to keep pH up to 7.9-8.0. I would welcome a pH boosting two part to replace my recipe-1 in use last 4-5 years.
I now have a dosing pump which is affordable and accurate so I can spread my dosing as widely as required. I initially voted option 1 as I have no issue with current recipe-1 strength but equally happy with option 3.

Is there an issue with safety using Caustic Soda ...in the hands of klutzy reefers like me..? I guess not. It is just that the current formulae are so benign that it is a bit of a change....like a locked dosing cabinet with toddlers.

 

[spscrackhead]

@Randy Holmes-Farley How would one make a 2 part solution with food grade sodium hydroxide instead of carbonate? The PH boost is very appealing!

 

[Mindi]

and when you come up with the recipe.... hopefully accommodate dry NaOH as an alternate ingredient..?

 

[maroun.c]

Maybe some additive to allow the alkalinity part tobdisdolve better. I always have around 10percent that settles. Not bad big deal but just an annoyance and I guess messes up the balance between part A and B.

 

[Mindi]

hmmm...do you bake the carb soda well..?? I sometimes have a little residue but not much

 

[maroun.c]

Yes I bake it. Never tried without baking as I appreciate the PH rising effect. Tried to warm up the water before mixing and it did help a bit but not much. Have even ran a strong pump in the solution for 24 hours but it had minimal effect. Taking the residue out and mixing with RODI water it will dissolve and as the concentrations for that gets messed up I use it for random adjustments it when I'm out of solution.

 

[Mindi]

there may be a difference in the product we are using? who knows. It would be great from my point of view if Randy comes up with a caustic soda based 2 part giving better pH....I am pouring money through my CO2 filter in the form of Medisorb medical sodalime....and really only getting 8.0 for all that.

 

[mcarroll]

In With The New...
I think a stronger/pH Up-style "Recipe #3" would be interesting to have around and to see folks do some experimenting with.

Folks using Recipe #1 might want it.

Would there be any difference in it's contribution to NaCl buildup over time compared to Recipe #1 or #2? Reducing or eliminating that buildup could be very interesting.

If it was cheaper to make (and to ship, as you noted) so that it actually resulted in cheaper products that wold also be fun!

...But Not Out With The Old
IMO, Recipe #2 is the most ideal recipe for tanks that are growing stony corals. Especially high-density stony coral systems.

Extra concentration, boosted pH and CO2-reduction actually seem to run slightly counter to some things...

Concentration

For dosing, I prefer a more-dillute solution regardless of which Recipe #. I always diluted both of them when I was dosing manually.

And with auto-dosers it's not too hard to keep a pair of 5 gallon containers for alk and Ca and that makes refills few and far between even at the (low) Recipe #2 concentration.​

pH and CO2
I think some of the conventional thinking on pH, CO2 and corals is somewhat less simple than we've traditionally all thought about it.

Yes they can be problematic.

But are they problematic per se?

Should every reefer who doses for corals be giving mindshare to CO2 reduction?

Should they be chasing NSW levels of pH?

I don't think so, when you really look...​

Here are a couple articles that kinda put a new light on these issues (vs conventional wisdom in the hobby) to show the complexity.....

• "Elevated" CO2 is only bad for stony corals under certain circumstances, not typical aquarium circumstances (where it's probably beneficial):
  Long-term effects of nutrient and CO2 enrichment on the temperate coral Astrangia poculata (Ellis and Solander, 1786)

• pH doesn't seem concerning...at least not to stony corals:
  Biological control of aragonite formation in stony corals