Calcium Levels ...not understanding why it won't go down :-(

Andrew Schubert · Dec 13, 2019

In my 120 gallon I have 32 Acro frags (3 about yr old mini colonies now, and the rest new within the last 3 months), along with a couple montis, snails, and finally starting to see the start of some coraline algae growing on the glass.

I picked up a DOS about 2 months ago and switched over to 2-part from Kalk dosing at that time. I've been dosing 21ml of BRS 2-part daily, holding an Alk level at 7.3dkh. However, my Calcium levels have been at 450. So over the past week I've been trying to lower that just a little to a more naturally 430-435 level. In order to accomplish this, I've turned off the Ca dosing, and am only dosing 21ml of Alk for the past week. And here is where I am confused????

Despite not dosing Ca at all this, my Alk level has still remained stable, but my Ca literally has not budged. According to my Red Sea test kit my Ca at the start of the week was 450, and then as of today, it is still reading 450.

Magnessium is ranging right around 1380.

Is there any reason why I would not be seeing a decline in Ca? This seems really odd to not see Ca change at all! Especially with so many acros in my tank...yes, small frags, but still! Thoughts, or suggestions would be very helpful.

Here is a pic of my tank! I took all the sand out of the tank about 4 months ago due to an algae issue at the time.

vetteguy53081 · Dec 13, 2019

May I suggest before concluding this is happening, it may be your test kit?
Take a water sample to a trusted LFS and have them test it for you and see what readings they come up with to confirm and compare with your readings

Hemmdog · Dec 13, 2019

Did your salinity rise by any chance?

Andrew Schubert · Dec 13, 2019

vetteguy53081 said:
May I suggest before concluding this is happening, it may be your test kit?
Take a water sample to a trusted LFS and have them test it for you and see what readings they come up with to confirm and compare with your readings

I think you might be right. I have just recently had to replace my Red Sea Regents. Thankfully, my old set was still in my garbage can. I just pulled it out and tested with the remains of that test and my Ca is reading 420 with that test. Retested with my new kit and it reads 450. Think I'll need to reach out to BRS to get a replacement kit sent.

Randy Holmes-Farley · Dec 13, 2019

How much alk did you dose in total dKH? Calcium decline is much harder to measure easily, but is likely about 18-20 ppm calcium for each 2.8 dKH of alk, assuming water changes and a few other things didn’t mess with it.

Andrew Schubert · Dec 13, 2019

Randy Holmes-Farley said:
How much alk did you dose in total dKH? Calcium decline is much harder to measure easily, but is likely about 18-20 ppm calcium for each 2.8 dKH of alk, assuming water changes and a few other things didn’t mess with it.

According to brs calculator 21ml in my tank would be about .25dkh a day

Randy Holmes-Farley · Dec 13, 2019

Andrew Schubert said:
According to brs calculator 21ml in my tank would be about .25dkh a day

then you will not be able to detect the expected calcium drop of less than 2 ppm per day. Even over 10 days you are near the ability of a kit to see it.

my advice is always dose both equally based on alk, and long term adjust the calcium slowly up or down as needed.

Andrew Schubert · Dec 13, 2019

Yea I've always dosed equal amounts. But it seems like my tank uses up a tad bit more alk then ca, and slowly gets out of wake after awhile

Randy Holmes-Farley · Dec 14, 2019

Andrew Schubert said:
Yea I've always dosed equal amounts. But it seems like my tank uses up a tad bit more alk then ca, and slowly gets out of wake after awhile

Which is a fine reason to slowly adjust the two to match the demand.

Gary Inwood · Dec 18, 2019

I have stopped dosing cal for around 5 months now because my levels was 500 and it is still the same even using two different test kits.
Alk is at 12, mag at 1470 so i am stuck trying to figure it out how to lower cal.

Andrew Schubert · Dec 18, 2019

Gary Inwood said:
I have stopped dosing cal for around 5 months now because my levels was 500 and it is still the same even using two different test kits.
Alk is at 12, mag at 1470 so i am stuck trying to figure it out how to lower cal.

Alk at 12 seems crazy high! Maybe that could be your problem? Do you have any Acros. ..I bet the tips are bleached at that level if u do?

motortrendz · Dec 18, 2019

Andrew Schubert said:
Alk at 12 seems crazy high! Maybe that could be your problem? Do you have any Acros. ..I bet the tips are bleached at that level if u do?

That's not true for high alk. It's a spike in alk that will cause this. I accidentally had my alk rise over 22dkh when I first got my calcium reactor. it took about a week to go from 10 to 22. And about 6 weeks to come back down. Didnt loose or bleach one acro.

Andrew Schubert · Dec 18, 2019

motortrendz said:
That's not true for high alk. It's a spike in alk that will cause this. I accidentally had my alk rise over 22dkh when I first got my calcium reactor. it took about a week to go from 10 to 22. And about 6 weeks to come back down. Didnt loose or bleach one acro.

So your arguing a spike causes burnt tips not high alk, by giving an example how u had a spike in your tank that didnt cause burnt tips? Probably the reason you didnt get any burnt tips was because you didnt leave your tank at that high of a level.

From my understanding the reason acros get. Burnt tips is because high alk causes corals to grow faster then they can produce zooxanthellae, causing bleached tips and stressing the corals.

I lowered my alk from 9 down to 7 and within a week saw colors in my acros I've never seen before..it was amazing! Lower all = more color, higher alk = faster growth...the balance between the 2 is up to the reefer. But dkh too high is just gonna do harm.

motortrendz · Dec 18, 2019

I'm not arguing by your aspect at all. I'm just saying having higher alk isnt exactly what causes the burnt tips. A quick spike causes burnt tips. Or a drastic fast change. My point was I had it go up over the course of a week or maybe a week and a half. And I didnt have any problems. And I also didnt drastically change it back down. I let it come down slowly. I run my alk normally at 10.5-11 and I have great colors. No need to get upset.

didnt mean to offend you or get you worked up.
I also think every system is different and depending on nutrient levels a change in alk can cause more issues. Expecially in a lower nutrient system. I agree that a lower dkh is better. But in higher nutrient systems(like mine) it's a little more forgiving and a higher alk level is tolerated.

danieyella · Dec 18, 2019

IDK, I have this same problem. My Calcium just never seems to drop, I dose alk and mag regularly though

Andrew Schubert · Dec 18, 2019

danieyella said:
IDK, I have this same problem. My Calcium just never seems to drop, I dose alk and mag regularly though

Everyone's tank is a little different, but if it was me I'd stop dosing both until both are in a desired range.

danieyella · Dec 18, 2019

Andrew Schubert said:
Everyone's tank is a little different, but if it was me I'd stop dosing both until both are in a desired range.

I stopped dosing mag and alk experimentally for a week and they dropped fast, calcium just never seems to drop and I don't dose it. I test with hanna, red sea, and salifert and they all test consistent right around 430 (except the hanna randomly, but i know their calcium is finnicky)

Jeeperz · Dec 18, 2019

This is why I don't dose 2 part. I never tested a need for CAL but with everyone on the 2 part bandwagon, I followed. Caused an ALK crash. So I reset and only dose alk daily and weekly water changes. My Cal and mag never change. Only ALK. I'm up to 15ml red sea ALK daily in my 20 gallon. I'm no professional, but this is how 2 of my tanks run.

Gary Inwood · Dec 19, 2019

Andrew Schubert said:
Alk at 12 seems crazy high! Maybe that could be your problem? Do you have any Acros. ..I bet the tips are bleached at that level if u do?

I have sps/acros and No i do not have bleached tips, i just have very slow if any growth

Randy Holmes-Farley · Dec 19, 2019

danieyella said:
IDK, I have this same problem. My Calcium just never seems to drop, I dose alk and mag regularly though

thet can only be for one of three reasons:

1. salt mix is high in calcium and water changes are keeping it up. Some have this attribute.
2. You are adding it and do not realize it (tap water, other additives, etc).
3. Measurement error.