Calcium Problems

[ismira]

I’ve been having problems lately keeping my calcium up despite increasing dosage.

My tank is a 120Litre mixed reef about 2.5yrs old.

My typical parameters over the years are ALK 7.5dkh, Ca 420ppm, Mag 1350ppm and PH 8.2, for testing said parameters I use a Hanna checker (ALK), Salifert (Ca) and AquaForest (Mg).

I dose using a dosing pump and dose my major and trace elements using Coral Essentials primary care range +trace.

I currently dose 24mL of ALK and 30mL of Ca.

My issue started around mid September,

15th Sep - 8.7 dKH, 430ppm Ca

27th Sep - 8.3 dKH, 400ppm Ca, 1245ppm Mg (upped my Ca dose by 0.5mL)

8th Oct - 8.8 dKH, 385ppm Ca, 1285ppm Mg (upped my Ca dose by 0.5mL)

18th Oct - 8.4 dKH, 375ppm Ca, 1245ppm Mg (upped my Ca dose by 0.5mL)

I sent out an ICP test, 421ppm Ca, 1304ppm Mg

2nd Nov - 8.4 dKH, 360ppm Ca, 1200ppm Mg (upped my Ca dose by 1mL)

21st Nov - 8.7 dKH, 350ppm Ca, 1215ppm Mg

I went to the LFS and had them test my water too,

3rd Dec : 8.6 dKH, 328ppm Ca, 1365ppm Mg

they use the SpinTouch FX

My LFS suggested increasing dosage until I see an increase in calcium or trying a different brand of calcium additive.

Am I overthinking this? I just don’t understand why calcium was fairly stable all these years with small increases and now it just seems to be continuing to drop despite adding extra doses.

I have another reef tank that uses the same calcium solution and test kits and that tank doesn’t seem to be having any issues.

 

[JonasRoman]

Calcium is quite stable so we must exclude other reasons. I can see that all time you have low Ca also quite low Mg, so are you sure this isnt a salinity issue?. every time you have such low values always start to check salinity, and do not just check with an electronic device as thise may be wrong, but doubke check with a reliable analogue way of testing, like refractometer.
If Ca still is low, AND your tests is 100% correct, AND you can see that dosing pump is doing same, then I suspect it could be a bad batch of the Ca supplement. Thats has happended before, because one thing is for sure, Ca is NOT consumed like that.

So check
1) salinity
2) dosing pump, giving equal? time to calibrate them?
3) If 1 and 2 is fine, I would double check the Ca bottle batch. It should be information on the bottle and by dilution you can check its concentration.

/Jonas

 

[ismira]

Yes salinity has always been at 1.026 when doing these tests. I use a refractometer to test my salinity which I calibrate with RODI water. My ICP test also came back at 35ppt for salinity and the LFS also tested with their refractometer and also got 1.026.

I have also checked my dosing line for air bubbles and checked that the dosing pump is still dosing the correct amount. I can’t seem to find anything wrong with the dosing pump/air line/dosing container. So I believe it’s doing what it’s meant to.

My main thoughts after bad test kit was bad Ca batch like you suggested. I may go and get another brand of Ca and see if anything happens.

The corals all look fine, everything still opens everyday, nothing is sulking or looking worse for wear.

 

[twentyleagues]

Calcium and magnesium tests are frequently wrong. ICP shows it within an acceptable range when your home tests do not. For every 2.8 dkh used of alk in a reef tank aprox 20ppm of calcium and 2ppm of mag are used depending on what is using it coral or coralline algae, coralline uses a little more mag. So knowing this those test numbers can not be correct. Things that could cause it are an imbalance in dosing, you checked your dosing to insure these are correct. Incorrect salinity, you triple checked that and referenced icp as well. Do you do regular water changes? Have you checked the fresh made saltwater parameters? If using saltwater of lower parameters it would cause a drop in these elements. If you use a balanced dosing regimen and are sure of your parameters in fresh saltwater there is very predictable element usage anything outside of this is most likely incorrect. I am not a chemist or a biologist so take my mutterings with a grain of salt like most calcium and magnesium tests.

When I test calcium (infrequently) and magnesium (rarely) I use Redsea pro test kit. Calcium seems in range and I can get very close test numbers on multiple tests, typically within 10-20ppm. Mag also within a range but rarely is it the same test result over multiple tests on the same sampling of water, typically anywhere from 20-200ppm.

 

[Randy Holmes-Farley]

Not sure why they did this, but Coral Essentials is not designed for 1:1 dosing. If their calculator is accurate, one needs 1.4 times as much of the alk as the calcium. You are dosing more of the calcium than the alk.

Unless you are adding additional alk some other way, there must be a test issue, or water changes messing with the values.

 

[ismira]

Do you do regular water changes? Have you checked the fresh made saltwater parameters? If using saltwater of lower parameters it would cause a drop in these elements.

I do a 10% water change once a fortnight using natural sea water. I did check the Ca on the seawater with my test kit and got 415ppm Ca.
I have tried to not panic and have a knee jerk reaction to what I’m seeing with my test numbers because it doesn’t add up, I don’t want to go dumping stuff in the tank and mess it up when things appear to be ok.

 

[JonoH]

Not sure why they did this, but Coral Essentials is not designed for 1:1 dosing. If their calculator is accurate, one needs 1.4 times as much of the alk as the calcium. You are dosing more of the calcium than the alk.

Unless you are adding additional alk some other way, there must be a test issue, or water changes messing with the values.

Interesting, as I use the same stuff, anddose a lot less of the Calcium than the Alk (like close to half). I used to dose 1:1 but my Calcium shot up super high!

Their Alk solution is super concentrated. (Like double the Randy's #1 Recipe which I also use - so have to double dosing when swapping)

What test kits is the OP using for Calcium? The Hanna one is very inaccurate, better off with the Red Sea Pro Kit.

 

[ismira]

Not sure why they did this, but Coral Essentials is not designed for 1:1 dosing. If their calculator is accurate, one needs 1.4 times as much of the alk as the calcium. You are dosing more of the calcium than the alk.

That explains why I used to dose more AlK than anything else, I was always confused when people say you should dose 1:1 and I wasn’t.
Up until recently I believe I was dosing more ALK than Ca, I have been dropping my ALK dose over the weeks because my dKH has been creeping up. I think this is because my acros brown out in the heat (I live in Aus it’s summer here) and I guess stop growing or don’t grow as much.

 

[ismira]

What test kits is the OP using for Calcium? The Hanna one is very inaccurate, better off with the Red Sea Pro Kit.

I’ve been using Salifert for Ca ever since I started reefing, I think I will go out and get Red Sea and see what results I get.

 

[ismira]

So I got a Red Sea Ca test kit and got similar results as before 330-340ppm Ca. I also did a little test by adding my Ca supplement to a bucket of saltwater and testing it each time to see if the Ca would increase, which it did.
So my test kits seem to be working, my Ca supplement seems to be working, the only thing I can think is that I had bubbles in my dosing line. Every time I checked liquid come out the end but maybe just bad luck that there were multiple small bubbles?
I think I’m going to add small extra doses by hand each day till I get it back up to 400+ppm.