Calcium won't increase

Duncan Tse · Apr 24, 2020

All test done on the salifert calcium test kit

4/20 cal = 390 then dosed 70mL CaCl sln
4/21 cal = 410 then dosed 70mL
4/22 cal = 430 then dosed 70mL
4/23 cal = 430 dosed 70mL
4/24 cal = 430 again

Using the BRS calculator I'm suppose to be dosing 70mL of calcium chloride sln to my 37 gallon tank to raise cal by 20ppm

Any explanation on why it's not going up anymore when the first few days I saw an accurate increase?

Alk = 9
Mg = 1470
Sg = 1.026

rastareefs · Apr 24, 2020

Sometimes magnesium will play a role in the balance of the Alkalinity and Calcium. 430 is an adequate Ca level in my opinion, but I would try to get your Mg down into the mid 1300s and try it again if you really want to raise your Calcium.

X-37B · Apr 24, 2020

Looks like 70ml is giving you steady 430 cal. Thats a good number and its what your tank is using daily. Stability is what you want.

Duncan Tse · Apr 25, 2020

rastareefs said:
Sometimes magnesium will play a role in the balance of the Alkalinity and Calcium. 430 is an adequate Ca level in my opinion, but I would try to get your Mg down into the mid 1300s and try it again if you really want to raise your Calcium.

I've always ran mg in the 1400s with low calcium around 380. I felt like it was borderline too low so thats why I'm trying to raise it to 450. Yea honestly right now i think I'm just going to keep it at 430 as it doesn't seem to be going up. Just curious on why it wouldn't increase and maybe mg has something to do with it .

90's reefer said:
Looks like 70ml is giving you steady 430 cal. Thats a good number and its what your tank is using daily. Stability is what you want.

I'm dosing 12mL alk and ca right now to maintain my levels. the 70mL was just to bump up my Ca levels. My tank isn't using 70mL daily.

hometown9 · Apr 25, 2020

I agree with stability. I had a problem with high Mg (1400) and moderate Alk (9), but low Ca. Realized that trying to chase the number (450+) was futile so just backed off and let it reach equilibrium. So far so good. Stay the course.

Randy Holmes-Farley · Apr 25, 2020

There is never a case where calcium won't rise if you add enough, assuming you are not also adding alkalinity at the same rate.

430 ppm is perfect, but if you have confidence in your kit, and want it higher add more.

Why didn't it rise as much as expected?
1. Consumption between additions
2. Maybe you made it to the wrong dilution
3. Incorrect calulator usage
4. Incorrect water volume estimate
5. Test error since +/- 20 ppm is not an unreasonable error bar on that kit.

maybe all five lol

Randy Holmes-Farley · Apr 25, 2020

Calculator issue?

If you dosed my DIY recipe 1 (which is what BRS usually uses, but what exactly did you make???)

Reef Chemistry Calculator

enter 37 gallons, randy recipe 1

a 50 ppm boost to calcium will take 189.3 mL

Duncan Tse · Apr 25, 2020

2.5 cups calcium chloride in 1 gallon water.

I wanted to go slowly so I only dosed 20ppm per day.

The first few days were fine as I've seen an increase of 20ppm with 70mL sln

From 390 to 410 to 430 but it was at 430 when I stopped seeing an increase

Randy Holmes-Farley · Apr 25, 2020

Duncan Tse said:
2.5 cups calcium chloride in 1 gallon water.

I wanted to go slowly so I only dosed 20ppm per day.

The first few days were fine as I've seen an increase of 20ppm with 70mL sln

From 390 to 410 to 430 but it was at 430 when I stopped seeing an increase

There’s no reason to go higher, but just add more if you want to. I expect it just reflects imperfect hobby testing.