Water too (NaCl) salty

[Randy Holmes-Farley]

If you are mixing the Biocalcium into fresh water before dosing, that would likely be precipitating some calcium carbonate, which could show up as not enough alk.

It is also possible they don't add enough alk to it. I've not seen an exact recipe for it.

 

[mcarroll]

Good thoughts!

However, I'm not pre-dissolving....just sprinkling the dry product as lightly as possible over an area where it can quickly get picked up in the turbulence from a pump (but not sucked INTO a pump nor blown INTO a coral).

I'll continue to log my tests with dates (only a few so far) so maybe a more clear picture will emerge, but so far it seems the alk contributions are inconsistent...seems like a problem with the formulation would be more consistent.

I don't know if it would be worth the bother, but I could theoretically measure my BioCalcium's formulation by taking a sample of Reef Crystals and boosting half of it with X grams of BioCalcium....then dissolving the two halves (one boosted, one not) in equal parts water of appropriate volume and then testing alk and Ca on the two samples as normal and comparing the results, right? (Is there a more direct way since it can't be dissolved in plain water?)

(I'm almost ready for another bucket of road salt ($6/year) and some baking soda. And a ReefFiller for water changes! )

 

[Randy Holmes-Farley]

If they made it exactly the to ratios present in calcium carbonate, that too will lead to calcium rising relative to alkalinity.

That's what happens in the long term my case with limewater, because magnesium and strontium get into growing calcium carbonate crystals in place of calcium. So the calcium consumption is actually a little less than the alkalinity when calcium carbonate forms in seawater.

My two part takes that into account, but Biocalcium may not.

 

[mcarroll]

Another good point. It's true I only rarely had to adjust Ca or carbonates on two-part. I had to adjust for moisture getting into my CaCl2 more often than I had to adjust Ca:alk.

Hm...I guess I'm not sure how big of an accounting you're describing vs (e.g.) limewater. My "loss" of alkalinity seems somewhat dramatic for only around a few days' time.

Will keep up testing/dosing and keep making adjustments as needed - hopefully this evens out soon. Almost 1/2-way through this container of BioCalcium, so a verdict is coming sooner than later!

 

[Randy Holmes-Farley]

In a few days it likely just means you are not adding enough, and the calcium hasn't had time to drop much. Under-dosing to arrive at a 3 dKH drop in alkalinity would only cause about a 20 ppm drop in calcium, which might go unnoticed with most kits.

It takes quite a while for the effect I was referring to to be seen.

 

[mcarroll]

One thought after re-reading my last comment: If the BioCalcium is delivering "less than expected" alkalinity...I meant less than expected after consulting the Reef Chemistry Calculator (RCC). I understand the possible formulation issues Randy brought up (in my other thread?), but wouldn't these be accounted for by the time the RCC is handing out advice?

In any event, I'm finished with the Tropic Marin BioCalcium container, so the experiment (such as it was) is over. Without making any adjustments, here are my test results:

s.g. 1.026 (already creeping back up)
Ca 420 ppm
alk 2.5 meq/L

I'm making an adjustment now using Recipe2/baking soda and will retest a bit after it finishes dripping in.

 

[mcarroll]

Just blindly tested calcium before the alk drip was done (assumed it was done) and got a somewhat surprising result, with the test registering 455 ppm.

I've never willfully tested during dosing, so I don't know what "normal" would be, but I think I would have guessed that the extra CO2 in the Recipe2 would cause an early color change, not a later one.

Does this make sense/anyone know what's going on with this result? (Just curious...don't really care.)

So much for today...will retest after I get some sleep!

 

[Randy Holmes-Farley]

One thought after re-reading my last comment: If the BioCalcium is delivering "less than expected" alkalinity...I meant less than expected after consulting the Reef Chemistry Calculator (RCC). I understand the possible formulation issues Randy brought up (in my other thread?), but wouldn't these be accounted for by the time the RCC is handing out advice?
.

I'm not sure how the chemistry calculator determined the potency per unit of volume or weight. It might be manufacturer info, or a calculation of some sort. For Biocalcium, I'd guess it is manufacturer info, but would be more than a decade old and the manufacturer may use more or less dense materials now.

 

[Randy Holmes-Farley]

Just blindly tested calcium before the alk drip was done (assumed it was done) and got a somewhat surprising result, with the test registering 455 ppm.

I've never willfully tested during dosing, so I don't know what "normal" would be, but I think I would have guessed that the extra CO2 in the Recipe2 would cause an early color change, not a later one.

Does this make sense/anyone know what's going on with this result? (Just curious...don't really care.)

So much for today...will retest after I get some sleep!

I don't think the pH or CO2 will have much impact on the calcium testing. Is that what you mean?

 

[mcarroll]

Ya...my thinking was that the color transition is dictated by a change in pH that happens as you drip the last reagent (at least that's my understanding)...and the kit would therefore have to assume the starting amount of CO2 (and pH) of the sample being tested. If the sample is adulterated in a way that alters starting pH, wouldn't that affect the timing of the color change, skewing the final result?

It was a theory. ....any other ideas that could explain calcium apparently jumping like that during a baking soda drip? (I.e. Where no calcium is being added.)

 

[mcarroll]

I finally retested and got:
Ca: 445 ppm
alk: 3.0 meq/L

...so I suppose the earlier Ca result in post #46 is actually the one in question...not the 455 ppm from the last reading. No less mysterious since I can't explain that reading being low.

That also means the disparity with alkalinity was greater than I thought it was. I guess at least I'm on a consistent path with the last two tests.

Going forward I've got a gallon of calcium chloride stock solution (Brightwell, dry mix) and plenty of baking soda to keep me back on two-part for at least a short while. Once the numbers are consistent (and good) for a while, I may try some dry calcium acetate or figure out another alternate course.

 

[Randy Holmes-Farley]

Ya...my thinking was that the color transition is dictated by a change in pH that happens as you drip the last reagent (at least that's my understanding)...and the kit would therefore have to assume the starting amount of CO2 (and pH) of the sample being tested. If the sample is adulterated in a way that alters starting pH, wouldn't that affect the timing of the color change, skewing the final result?

It was a theory. ....any other ideas that could explain calcium apparently jumping like that during a baking soda drip? (I.e. Where no calcium is being added.)

A calcium test is largely independent of pH.

You add a dye that binds calcium and gives a certain color when bound.

Then you slowly add a strong calcium chelator (such as EDTA) and it rips the calcium from the dye, and the dye changes color. So when there is no longer any calcium bound to the colored dye, you see the endpoint. So the amount of EDTA added = the amount of calcium present.

 

[Randy Holmes-Farley]

I finally retested and got:
Ca: 445 ppm
alk: 3.0 meq/L

...so I suppose the earlier Ca result in post #46 is actually the one in question...not the 455 ppm from the last reading. No less mysterious since I can't explain that reading being low.

That also means the disparity with alkalinity was greater than I thought it was. I guess at least I'm on a consistent path with the last two tests.

Going forward I've got a gallon of calcium chloride stock solution (Brightwell, dry mix) and plenty of baking soda to keep me back on two-part for at least a short while. Once the numbers are consistent (and good) for a while, I may try some dry calcium acetate or figure out another alternate course.

Those current values look fine to me.

 

[mcarroll]

The only minor gripe is that 420/3.0 was the target. In using up the last bit of the product I'm sure I overdosed slightly vs what was called for to reach 420 ppm (accounting for the Ca level), meaning that alkalinity lagged more than I'd like. (As you suggested might be the norm, depending on product design.)

That'll just be something to keep in mind.

I guess I've grown to like the precision of two-part. Will post if/when I try calcium acetate though!