Sudden calcium drop off while alk is stable and dosing

[kwall737]

So within the last 2-3 weeks, my calcium levels have dropped off from the 420-430 range, down to 384 in the most recent test. Alk is stable between 8.5-9, salinity at 1.025, nitrate at 5 and temp of 77f. I have a mixed reef with mostly softies and dose Tropic Marin AFR a couple times a week to keep my alk stable at 8.5-9. Anyone know what could cause this sharp calcium drop in the last few weeks, and what i could do to get it back up without spiking the alk as well? Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

It may just be test error, or it may be that something else is adding alkalinity, such as declining nitrate. Anyway, just dose a bit more calcium and see what happens.

 

[kwall737]

It may just be test error, or it may be that something else is adding alkalinity, such as declining nitrate. Anyway, just dose a bit more calcium and see what happens.

Hey Randy, appreciate the reply! So testing both Alk and Calc using Hanna testers, and have been testing the exact same way since i started testing 5 or 6 mo ago ... so don’t think it’s a testing error. Also dosing All For Reef when i do add anything, and from what i understand, that should bring both parameters up when i dose like it’s done until just recently (not bring Alk up, with Calc going down - just doesn’t make much sense to me). What would you recommend to just bring up Calc in my scenario?

 

[Randy Holmes-Farley Verified Community Expert]

Hey Randy, appreciate the reply! So testing both Alk and Calc using Hanna testers, and have been testing the exact same way since i started testing 5 or 6 mo ago ... so don’t think it’s a testing error. Also dosing All For Reef when i do add anything, and from what i understand, that should bring both parameters up when i dose like it’s done until just recently (not bring Alk up, with Calc going down - just doesn’t make much sense to me). What would you recommend to just bring up Calc in my scenario?

The alk provided by All for Reef may not be readily detected, so I would use alk only as a way to ensure that you are not underdosing alk to the tank.

Use calcium chloride to make a calcium correction.

 

[kwall737]

The alk provided by All for Reef may not be readily detected, so I would use alk only as a way to ensure that you are not underdosing alk to the tank.

Use calcium chloride to make a calcium correction.

Thank you! Just ordered up some Ca chloride

 

[blasterman]

I vote testing error. Calcium does not drop unexpectedly unless it's being taken up by SPS / clams or precipitated out via massively high alk levels or too much kalk being dosed. Not sure how big tank this is either. Suddenly low calcium in a 10 gal nano is far less mysterious than a 100 gallon.

When I see a number like '384' I get skeptical. There is no consumer level calcium meter that doesn't cost less than a new SUV that can read calcium levels with that much precision. So, it's just a 3 digit number your meter is throwing up and we can only trust it's kinda close to what it says.

Not being familiar with calcium formate dosing my suggestion would be to make up a small amount of fresh salt mix at your tanks current density and test it. That should get you a rough idea because if your testing method is working the two readings should agree to some extent.

The wild card here is *if* your numbers are correct then your dosing is off. Since you are using an all-in-one it means your dosing is broke because if it was working you wouldn't be needing to add calcium chloride. If you have to suppliment discrete amounts of calcium chloride or baking soda it kinda defeats the purpose of an All In One doser, right? sorry...just keeping it real

 

[kwall737]

I vote testing error. Calcium does not drop unexpectedly unless it's being taken up by SPS / clams or precipitated out via massively high alk levels or too much kalk being dosed. Not sure how big tank this is either. Suddenly low calcium in a 10 gal nano is far less mysterious than a 100 gallon.

When I see a number like '384' I get skeptical. There is no consumer level calcium meter that doesn't cost less than a new SUV that can read calcium levels with that much precision. So, it's just a 3 digit number your meter is throwing up and we can only trust it's kinda close to what it says.

Not being familiar with calcium formate dosing my suggestion would be to make up a small amount of fresh salt mix at your tanks current density and test it. That should get you a rough idea because if your testing method is working the two readings should agree to some extent.

The wild card here is *if* your numbers are correct then your dosing is off. Since you are using an all-in-one it means your dosing is broke because if it was working you wouldn't be needing to add calcium chloride. If you have to suppliment discrete amounts of calcium chloride or baking soda it kinda defeats the purpose of an All In One doser, right? sorry...just keeping it real

No need to apologize, I’m here to find out what went wrong, or what I’m doing wrong! So it is a 130 gal system, and don’t dose anything other that the AFR maybe once a week to keep my Alk levels around 9.
So i agree with you on ‘384’ exactly being suspect, but even plus/minus 10 of that number is not at all where it was just a month ago. Since i started testing, my Calc was in the 410-430 range, which i was perfectly happy with. I use the Hanna tester, and am well aware of the issues with that particular one if you don’t follow the steps to a t (using distilled water, making sure the test tube is facing the same way and clean of fingerprints each time, etc) ... so i test exactly the same way each time. I added a few corals about a month ago (2 small monti caps, a green candy cane and blue sympodium), and don’t think that these smaller frags would contribute to that 30-40 Calc drop all the while my Alk numbers stayed in the 8.5-9 range. Here’s just a snapshot of them since July ... just seems like quite a drop off, and trying to figure out why!