Dose Ca too when dosing alk, even if Ca is fine?

Hal3134

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From reading other threads, it appears that Randy recommends dosing Ca 1:1 when dosing alk, even if Ca is reading fine. Is this correct?

My Ca tests consistently at 425+, but my alk drops at Least 0.1 per day. I’ve been dosing only alk because that is all my test kits (Salifert) said was needed.

I also know to dose mag when my Ca or alk bottles are empty, but now understand that I could dose mag at 1/6 of alk, regardless of my mag reading. Is this correct? My mag always tests at 1500.
 

Randy Holmes-Farley

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An alk drop of 0.1 dKh per day?

You'll never detect the proportional calcium or magnesium drop, and will never see the proportional amount added .

It would only be 0.7 and less than 0.1 ppm, respectively, of calcium and magnesium per day.

Thus, I'd add it, but if you don't, its no big deal.
 

Gtinnel

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It was the same for me when I first started dosing, and it quickly got to where I had to dose calcium too. I'd go ahead and start dosing both so you have everything setup when you need to dose calcium, assuming you're using dosing pumps and not doing it by hand.
 
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Hal3134

Hal3134

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An alk drop of 0.1 dKh per day?

You'll never detect the proportional calcium or magnesium drop, and will never see the proportional amount added .

It would only be 0.7 and less than 0.1 ppm, respectively, of calcium and magnesium per day.

Thus, I'd add it, but if you don't, its no big deal.
Not exactly. It was 8.6 five days ago. Then I added 1/4 cup of alk supplement. Today alk is 8.15.

but my question still applies. Did I understand correctly that we should be adding Ca whenever we also add alk?
 

Randy Holmes-Farley

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Not exactly. It was 8.6 five days ago. Then I added 1/4 cup of alk supplement. Today alk is 8.15.

I would add the calcium. By the time you detect a need, you'll probably have to add all that you would have added on a daily basis to get back to normal. :)
 
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Hal3134

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I would add the calcium. By the time you detect a need, you'll probably have to add all that you would have added on a daily basis to get back to normal. :)
Will do. Thanks.

So why have I never detected any Ca drop with my test kit? It’s been months or longer since I’ve added my Ca supplement.
 

Randy Holmes-Farley

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Will do. Thanks.

So why have I never detected any Ca drop with my test kit? It’s been months or longer since I’ve added my Ca supplement.

Likely because it started higher than normal (many salt mixes are above NSW) and the expected depletion rate is low when alk demand is low. Kits cannot readily detect differences of less than about 20 ppm.
 
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