CaSO4 vs CaCl2

[MichaelJ]

To be honest, I don't understand anything from the discussion above... If you tell me CaCO4 is better, fine by me I will get CaCO4

No worries - either salts will work. There will be more info on this when we get the CaSO4 vs. CaCl2 discussion moved to a separate thread.

Cheers,
Michael

 

[John q]

as they don't particularly care about conducting electricity and more about keeping their own internal salts at comfortable levels. So instead of worrying about how SO4-- and 2Cl- affect conductivity, it would be more effective do discuss what is easier to osmoregulate, if a single SO4 ion or 2 Cl ions.

Here's the thing. Shrimp couldn't give a toss about tds, cacl2, sulfates, so4, etc.etc
WHAT THEY DO CARE ABOUT IS STABILITY.

Just like plants STABILITY is the key.

 

[MichaelJ]

Here's the thing. Shrimp couldn't give a toss about tds, cacl2, sulfates, so4, etc.etc

Sorry John, Not sure if thats a blank slate advice on shrimp keeping you are trying to give here, but its making absolutely zero sense by any stretch of the imagination and is obviously completely wrong.

WHAT THEY DO CARE ABOUT IS STABILITY.

You’re caps lock seems to be stuck intermittently

Just like plants STABILITY is the key.

Now, on the other end of the spectrum, that makes totally sense and I agree on the value of stability, but stability at meaningful parameters obviously.

Cheers,
Michael

 

[Hanuman]

these are the results for my Macros and Micros.

Looks fine to me.

In regards to the RO water remineralization, I've decided to go with CaCl2 and MgSo4, however, I am not sure about the ratio ( CaCl2: MgSo4 = 3 :1 and add to my water until I get 5dGH ? ). Sorry for asking that many questions here... I am just changing too many things at once

No worries - either salts will work. There will be more info on this when we get the CaSO4 vs. CaCl2 discussion moved to a separate thread.

As Michael says, either will work but after doing my test (3 times ), he was right. CaSO4 will produce a lower TDS/EC than CaCl2. So for the sake of being cautious I'd go for CaSO4.

 

[Hanuman]

I've been using CaSO4 for years, but moving away from it and now using CaCl2, to reduce EC.

'll do a test tonight with my compounds to double check, just like you did.

Now, one word of caution here, CaCl2 is highly hygroscopic hence why it's used as a desiccant. Could it be that my CaCl2 has absorbed so much water that the actual content of Ca and Cl per weight is technically lower? Possible.

So I re-did my test and just before I continue with the results, I'll make this statement. I was wrong.

300ppm Ca in 1 L of RO water:

CaSO₄∙2H₂O: 1.29 gr --> 663 ppm [scale 500] 1337 μs/cm
CaCl2: 1.10 gr -->1020 ppm [scale 500] 2030 μs/cm

Then I realized my test was erroneous because I had left the CaCl₂∙2H₂O (dihydrate) selected in the CoreSettings tabs when in fact I should have selected CaCl₂ since after heating the compound CaCl₂ was now anhydrous. In other words I had added too much CaCl₂.

So I re-did the test again for CaCl₂. Here it goes:

CaCl₂: 0.83 gr -->835 ppm [scale 500] 1685 μs/cm
vs CaSO₄∙2H₂O which I tested earlier:
CaSO₄∙2H₂O: 1.29 gr --> 663 ppm [scale 500] 1337 μs/cm

CaSO₄∙2H₂O still wins the contest and shows a lower EC.

Although in order to corroborate these findings a GH test would have been ideal to make sure both solutions have the same hardness, unfortunately I didn't have a hardness test with me.

CaCl₂ is really problematic due to its hygroscopic property. You really need to keep that compound locked up somewhere hermetically else it just sucks up all the water around and will end up dropping your GH with time.

 

[burr740]

Wow this is some level-10 fert talk you dont see every day. It's like I stumbled into a gaggle of professors...good stuff!

Re the addition of potassium sorbate and ascorbic acid. Since you're doing micros and macros separately, ascorbic acid alone will typically suffice for the micros as long as you're mixing with a pure water source. You definitely need it to keep everything in an available state.

Potassium sorbate is more of a strong mold/fungus preventative. Personally I have to add potassium sorbate to my macros. Maybe because I use "greenhouse grade" salts, not sure really but macros will turn slightly brown after a couple of weeks and develop some kind of weird gelatin looking chunks w/o it. Micros, in my personal experience, dont really need it. I have a test batch from 2018 in a clear glass jar that sits around in normal room lighting that is still crystal clear.

For anyone making an all-in-one solution definitely use both

 

[Hanuman]

Wow this is some level-10 fert talk you dont see every day. It's like I stumbled into a gaggle of professors...good stuff!

Re the addition of potassium sorbate and ascorbic acid. Since you're doing micros and macros separately, ascorbic acid alone will typically suffice for the micros as long as you're mixing with a pure water source. You definitely need it to keep everything in an available state.

Potassium sorbate is more of a strong mold/fungus preventative. Personally I have to add potassium sorbate to my macros. Maybe because I use "greenhouse grade" salts, not sure really but macros will turn slightly brown after a couple of weeks and develop some kind of weird gelatin looking chunks w/o it. Micros, in my personal experience, dont really need it. I have a test batch from 2018 in a clear glass jar that sits around in normal room lighting that is still crystal clear.

For anyone making an all-in-one solution definitely use both

Are you the almighty Burr740 from TPT? Would ne nice to see you more often here at UKAPS.

Yes sometimes we get nerdy, often times unnecessarily, but doesn't hurt if at the end some of us end up learning something.

 

[burr740]

Lol, idk about all that but thank you for the kind words! Your calculator is really nice btw

 

[John q]

Sorry John, Not sure if thats a blank slate advice on shrimp keeping you are trying to give here, but its making absolutely zero sense by any stretch of the imagination and is obviously completely wrong

Lol, fair doo's, my statement was probably a bit to generalised.

Point I was trying to make is that whether one uses Calcium Sulfate or Calcium Chloride to raise gh the difference in Tds will have a negligible impact on the health of the shrimp.

Of course if somebody's tds readings are outside the range they want then switching between these salts makes perfect sense.

 

[dw1305]

Hi all,

CaCl₂ is really problematic due to its hygroscopic property. You really need to keep that compound locked up somewhere hermetically else it just sucks up all the water around and will end up dropping your GH with time.

It is actually used a desiccant and is <"deliquescent">, which is why the solubility value is immense (<"CaCl2.6H2O = 81.1 g/100 mL (25 °C)">). This doesn't help once the calcium ions (Ca++) are in solution, they will still combine with a <"lot of different anions"> and precipitate out of solution.

CaSO₄∙2H₂O still wins the contest and shows a lower EC.

I honestly don't think it matters, but I might be tempted to use the calcium sulphate dihydrate (CaSO4.2H2O) if I want to decouple dGH and dKH. I'll be honest, I would a need a really good reason to stop <"using a dash of hard tap water"> as my remineraliser.

cheers Darrel

 

[Wookii]

In regards to the RO water remineralization, I've decided to go with CaCl2 and MgSo4, however, I am not sure about the ratio ( CaCl2: MgSo4 = 3 :1 and add to my water until I get 5dGH ? )

Just to clarify the ratio of 3:1 is Ca:Mg, not the raw salts of CaCl2 ands MgSO4. In terms of physical weights for those salts, adding almost equal weights of each salt will result in an approximately a 3:1 Ca:Mg ratio.

 

[MichaelJ]

While @Hanuman 's persistent effort indeed confirmed my observation that CaCl2 increases EC over CaSO4 for the same calcium target, some interesting questions still remains about the predictability of EC when diluting salts.

Specifically this excerpt from my post above:

One curious thing about this is that the numbers aren't scaling linearly at all, as I would have expected.... relative to my first test I would have expected the CaSo4 solution at 64 ppm of Ca to yield closer to 200 ppm (64 ppm Ca / 20 ppm Ca x 62 ppm TDS) = 200 ppm . and the CaCl2 to be closer to 400 ppm. I can't explain this discrepancy - other than perhaps the TDS meter. Of course not many among us will target 64 ppm of Ca with RO water, so I guess it's more of academic interest, but still.

Now I am not a chemist, but I think it goes like this; The salts we are adding to our aquarium water is usually considered strong electrolytes - chemistry divides electrolytes into weak and strong electrolytes - a strong electrolyte will conduct better than a weak electrolyte - in other words, the extent the salt will undergo ionization when diluted determines the conductivity. Thats fair enough, I think.
Kohlrausch's Law simply states: the equivalent conductivity of an electrolyte at infinite dilution is equal to the sum of the conductances of the anions and cations. This suggest that you can essentially derive the conductivity from simply summing up the ions. However, based on experimental data Kohlrausch proposed the non-linear law for strong electrolytes at low concentration (supposedly, what we are dealing with in the hobby):

What the math above boils down to, is that the conductivity depends (besides the ionic conductance) on a couple of additional factors; such as concentration (c), and factors mostly determined empirically and depending on the type of salts we are diluting.

The key insight from the formulation above is that the conductivity depends on the square root of the concentration, causing the increase in EC to taper of as we increase the concentration.

So tying this into our conversation about CaSO4 vs. CaCl2 at very low concentration, I think this explains why I see a bigger relative difference in EC when targeting lower levels of Ca and the difference narrows as we increase the concentration.

@dw1305, @X3NiTH, any thoughts on this?

Cheers,
Michael

 

[X3NiTH]

I read the paper and came to the conclusion that Crowd Dynamics plays a great part in this in that the lower the ionic concentration the greater the ions are free to move around without impedance, and the resulting conductance is higher, put more ions in the way and there is a resistance to free passage lowering the energy in the system overall averaging out the conductance. You can calculate what you think you may have but the variable dynamics of the system impacts the overall result.

And then there’s the not so perfect sample with impurities that also get in on this game and are they synergistic or antagonistic to the free movement of other ions.

When there’s one ion in the stadium it can move wherever it wants as fast as it wants, put a million others in there and it be like queuing at a hotdog stand!

 

[MichaelJ]

I read the paper and came to the conclusion that Crowd Dynamics plays a great part in this in that the lower the ionic concentration the greater the ions are free to move around without impedance, and the resulting conductance is higher, put more ions in the way and there is a resistance to free passage lowering the energy in the system overall averaging out the conductance. You can calculate what you think you may have but the variable dynamics of the system impacts the overall result.

And then there’s the not so perfect sample with impurities that also get in on this game and are they synergistic or antagonistic to the free movement of other ions.

When there’s one ion in the stadium it can move wherever it wants as fast as it wants, put a million others in there and it be like queuing at a hotdog stand!

Yes, I think that is really what Kohlrausch is telling us... It's sort of counter intuitive (for me at least) though that the increase in conductance is falling off with concentration.... but I think your crowd analogy is spot on!

Cheers,
Michael