New RANDY's 2 part

The SeaChem supplement is mostly just epsom salt, so I think it's rather overpriced for that it is. The goal of the Mag Flake is to add magnesium without adding sulfate, to keep the ionic balance in better shape.
 
<a href=showthread.php?s=&postid=13689262#post13689262 target=_blank>Originally posted</a> by bertoni
The SeaChem supplement is mostly just epsom salt, so I think it's rather overpriced for that it is.
Thats something that i've seen bandied about by alot of people, it seems popular to bash the name brand stuff :)

However according to seachem it contains a NSW ratio of chloride to sulfate (9:1 by mol). This would actually make it almost pure Magnesium Chloride with only a tiny amount of sulphate, very different to epsom salts (and would negate the need to add MAG flake).
 
Wow thanks for pointing out that thread. I actually asked seachem tech support, and they answered specifically that the product contained a 9:1 ratio of chloride to sulphate!
 
<a href=showthread.php?s=&postid=13689649#post13689649 target=_blank>Originally posted</a> by Randy Holmes-Farley
IMO, you make a true two part, you probably need access to sodium sulfate or sodium hydrogen sulfate.

Is it possible in practice to rely on precipitation reactions to get these kind of harder to find solutions?
For example you could mix solutions of Sodium bicarb and magnesium sulfate to give you precipitated magnesium carbonate and a solution of sodium, sulfate and carbonate ions. Furthermore knowing the solubility of magnesium carbonate, it would be possible to calculate the exact concentrations of the ions in the remaining solution.

Definitely adding complexity, but still relatively simple for enthusiastic DIYers once someone has worked out all the correct concentrations :)
 
It has the ratio of chloride to sulphate, but it doesn't have the magnesium corresponding to the chloride part. It's just a mix of NaCl and epsom salts (unless it's been changed very recently), and the sodium isn't helping, in the end. In order to raise the magnesium a given amount, the sulfate rises the same as if you'd used epsom salts, except you're stuck with extra NaCl in the mix. I don't see the utility, but it can be done with plain salt.

If you search, you can find some posts from SeaChem as to why they don't (or didn't) use magnesium chloride: the issue of ammonia contamination.
 
For example you could mix solutions of Sodium bicarb and magnesium sulfate to give you precipitated magnesium carbonate and a solution of sodium, sulfate and carbonate ions. Furthermore knowing the solubility of magnesium carbonate, it would be possible to calculate the exact concentrations of the ions in the remaining solution.

Yes, there might be such a way to do that, but your tank will not be any better off, and all you save yourself is the occasional magnesium addition from the part 3. So you spend more time overall and do not get an improvement in the tank. :D
 
Alk recipe #1

Alk recipe #1

Randy,

I mixed up a batch of Alk recipe #1 last night and had to boil a portion in order to get it fully dissolved. So it occurred to me, rather than heating the baking soda in the oven, could you mix the baking soda and water and boil it for an extended time to drive off the co2?

Todd
 
<a href=showthread.php?s=&postid=13691505#post13691505 target=_blank>Originally posted</a> by Randy Holmes-Farley
all you save yourself is the occasional magnesium addition from the part 3. So you spend more time overall and do not get an improvement in the tank. :D

Yes very true, although there is a certain appeal in being able to make a 2 part that only has... 2 parts :p Anyways i am going to play around with the numbers (and salts!) this weekend and see what i can come up with.

One thing that i have found already is that for the alkalinity part, using your specifications (recipe #1, part 2), my calculations give *half* the alk concentration that you state. I'm assuming that half the carbonate content is lost as CO2 during the baking stage:

2NaHCO3 → Na2CO3 + H2O + CO2

ie for every 2 ions of CO3 bound in the bicarb, i end up with only 1 ion of carbonate after baking, hence halving the alkalinity when dissolved in water. Is this an incorrect assumption?
 
I mixed up a batch of Alk recipe #1 last night and had to boil a portion in order to get it fully dissolved. So it occurred to me, rather than heating the baking soda in the oven, could you mix the baking soda and water and boil it for an extended time to drive off the co2?

It certainly drives of much of the CO2, but I am not sure how complete it will be. Presumably it depends on time, etc.
 
2NaHCO3 → Na2CO3 + H2O + CO2

ie for every 2 ions of CO3 bound in the bicarb, i end up with only 1 ion of carbonate after baking, hence halving the alkalinity when dissolved in water. Is this an incorrect assumption?


One mole of carbonate provides two moles of alkalinity, twice as much as one mole of bicarbonate. So there is no loss of alkalinity on baking. :)
 
Ah i assumed carbonate ions only gave 1 unit of alk, thanks.

Anyways i have done some initial number twiddling using precipitation reactions, and one thing i have come up with (i think) is a way to produce the balanced Recipe #1, Part 3A *without* requiring any MAG flake.

To 1 litre of water add:
- 135g equiv of CaCl2 (DOW flake, turbo calcium etc)
- 234g equiv of MgSO4 (Epsom salts)

This gives you the following ions
- 1.22 mol Ca
- 2.44 mol Cl
- 1.94 mol Mg
- 1.94 mol SO4

The CaSO4 will precipitate out, leaving ~0 Ca and the excess SO4 (0.72 mol).

Converting mol to ppm this then leaves the solution at:
- Magnesium: 1.94 * 24 * 1000 = 47000ppm
- Sulfate: 0.72 * 96 * 1000 = 69000ppm
- Chloride: 2.44 * 35 * 1000 = 86000ppm

ie identical to the recipe that uses MAG flake. Anyways the big question (other than whether my maths is correct :) ) is how easy it is in practice to separate out the precipitated CaSO4... that will be my next step.

If all works out could be a nice way to DIY for people who can't source MAG flake or are worried about its impurities.
 
Alright i tested adding dissolved epsom salts (MgSO4) *directly* into the Ca and Alk parts. I did some rough numbers and with the correct ratios this should precipitate out calcium sulphate and magnesium carbonate, leaving an ionic residual of SO4 and Mg that is the exact ratio as needed by the ion-balanced 2 part (ie as with recipe #1 part 3a).

In practice there is *alot* of precipitate. I would say about a quarter of the volume settles out as precipitate, so unfortunately you either have to waste 25% of each batch, or compress it through a filter media.


In the meantime i have found a lab chemical supply company that sells MgCl2 and Na2SO4... Randy am i correct to assume that these can be used instead of MgSO4, and added directly to the Calc and Alk parts respectively to make up the required ppm of Mg and SO4?
 
So, Dowflakes and Peladow are or aren't safe Randy, I'm starting to get confused. I know at one point you mentioned the elevated bromide was a concern and then I saw you say it SHOULDN'T be of much concern.
Sorry to take the thread in a different direction, but this is a topic being debated in our club and I was debating whether or not to buy a 100# of Peladow or not.
Thank you Randy
 
Well, I think I've held a single position on this from day 1, and have not stated otherwise, but there are different uses, and that may cause the confusion.

1. For boosting a salt mix like Instant Ocean to NSW levels of calcium, new Dowflake is fine. There is no concern whatsoever.

2. For substantial daily supplementation with a two part using the new Dowflake, you will very likely see a rise in bromide. That size of that rise will depend on how much you use, what in the tank consumes bromide (like micro- and macroalgae algae), how often you do water changes, and how much bromide is in your salt mix.

What is not known is what negative effects one might observe with any given elevation to bromide. It might be that there are none at any level likely to be attained in reef tanks using new Dowflake. There is just no data that I've ever seen. So it may be fine, or it may not be, and that is why I characterize it as experimentation.

That said, I think many folks have now done it, whether they realized the issue or not, and I've not seen any reports of problems, but since we do not even know what to watch for, such issues, especially since they may be slow building, might get attributed to other or unknown causes.
 
Sorry if this question has already been asked, it's late and "my mind has gone....".
Can sodium carbonate (soda ash) be substituted for the baking soda in Randy's 2 part formula?? Also does the store bought baking soda have any additives that would differ from pure sodium bicarbonate? Just wondering as I have found a relatively inexpensive source for sodium bicarbonate.

So what's the consensus on finding an alternative calcium supplement due to possible problems with the new Dowflakes?? At this point it seems that many hobbyists have inadvertently been using the "bad" DowFlakes for some time without any adverse effects? Or perhaps its a long-term accumulative effect that will destroy everyones reef tank in the near/far future.... Heck, I may not be around long enough to realize the adverse impact of the bromide!!! LOL
 
Can sodium carbonate (soda ash) be substituted for the baking soda in Randy's 2 part formula??

If it is suitably pure, yes. You need less, but I'v not worked up the exact volumes to use.

Also does the store bought baking soda have any additives that would differ from pure sodium bicarbonate? Just wondering as I have found a relatively inexpensive source for sodium bicarbonate.

No, that's why I recommended it. :)

I think the bromide "experiment" by reefers is ongoing, but I've not heard of any bad effects yet.
 
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