Side by Side - Calcium with API and Red Sea Foundation

[DeepBlueSomething]

As my tank is maturing so are my methods -- and I wanted to share the first of my side by side.

Like many out there, I started with the reasonably priced and easily available API Test Kits and have relied on them for the first months of my tanks existence with good results to date - fish alive, corals alive.

As I have added more corals I have noted a decline in measured Ca - as expected as some is now being consumed. I am using IO Reef Crystals and no additional Ca supplementation at this time. Historical Ca results have from 440 ppm on initial set-up to a more consistent 380-360 ppm over the past 60 days.

Tonight, Side by Side testing was conducted:

• API Ca = 380 ppm
• RS, 1 = 460
• Rs, 2 = 440

To be fair, I was not expected an exact match, and it is my first time using the RS test kit. But the results present a quandary. Red Sea results say not supplement of Ca is needed currently, whereas my API results suggest some is needed.

My tank says its 'ok' but its young and I have added a number of LPS and a few SPS over the past few weeks.

So, what say you R2R? User error with new RS test? Poor API - don't trust it? Keep an eye on it?

I will follow this up tomorrow with the KH and Mg results side by side to see what else I can.

 

[Gareth elliott]

I find the results of the api calcium test are dependent on what you consider blue.
Do you stop when it is purple? Is there just a splash of pink? I still use the api test on occasion for ease of use. When verified on occasion against my salifert test, i just make sure i always use the same end point, no pink after swirled that holds for 5 seconds+, held against a 5000k cool white fluorescent.

 

[Cory]

If you pick the average of the three which is 426ppm calcium, and raise it to 450ppm, which is safe anyways, youd increase calcium by only 24ppm. Which would bring any of your results to:

380 ppm to 406ppm
460 ppm to 486ppm
440 ppm to 466ppm

All of which are acceptable. But 380ppm if real is getting low imo.

 

[Cory]

Fwiw my api and salifet calcium read the same.

 

[Gareth elliott]

Ime when i get a calcium reading that says i need to add at least 50 ml of ca i have a noticeable drop in alkalinity and or mg. So test these too. If i dont find a drop in anything else i retest.

 

[DeepBlueSomething]

Finished my side by side on KH tonight. Again, not surprised at the difference, but rather the magnitude. Fairly confident that the test elements are the same, with only minor differences.

API KH - 7.5 (color transition initiated at 7 totally completed at 8) -- but that is the difference of a single drop ie test precision.
Red Sea - 6.7 (low -- but an absolute, and repeated with identical results again)

Magnesium was 1300.

I dosed Ca @ 12ppm and added equal amounts of Alk solution. Will test Ca, Alk and Mg again tomorrow and see if anything starts dropping off or standing in line or whether I need to shift the balance of Alk and Ca solution addition. Tonight's additions are slow and steady to see what results we turn out tomorrow.

 

[DeepBlueSomething]

I dosed Ca @ 6ppm on Saturday (does on 1/4 was also 6ppm) with an equal amount of Alk. Tested Ca, Alk and Mg again tonight before WC:
(all tests with Red Sea; additives were Brightwell Reef Code A & B).
Ca 1/3 = 460, 1/9 = 460 (no change, predicted would have been ~470 based on dosing)
dKH 1/4 = 6.7, 1/9 = 8.1 (increase, predicted would have been ~1.3 based on dosing)
Mg 1/4 = 1300, 1/9 = 1040 (drop)

@Gareth elliott @Cory
So, for my first time dosing and feeling my way -- this seems somewhat as expected. Do you all have any thoughts or guidance for a new doser? Mine below... I plan to retest tomorrow - of course 10% WC with IO Reef Crystals is a new variable! Regardless, I am excited to continue to learn, improve my care for my reef and hopefully have healthy and thriving inhabitants! Thanks all

1. Ca dosing was small and made little to know change, especially with utilization
2. dKH increased as expected
3. Mg dropped quite a bit. Reading up on @Randy Holmes-Farley articles it seems the Mg drop could be due to its coating calcium carbonate; however, I don't believe that observation is consistent with 1 and 2 above nor the basic chemistry.

 

[Randy Holmes-Farley]

The magnesium drop is guaranteed to be testing error. There is no other possible or needed explanation. Such errors are very common.

 

[DeepBlueSomething]

Thanks Randy -- that was my gut, but didn't want to miss the chance for input from fellow reefers!

 

[Gareth elliott]

I dosed Ca @ 6ppm on Saturday (does on 1/4 was also 6ppm) with an equal amount of Alk. Tested Ca, Alk and Mg again tonight before WC:
(all tests with Red Sea; additives were Brightwell Reef Code A & B).
Ca 1/3 = 460, 1/9 = 460 (no change, predicted would have been ~470 based on dosing)
dKH 1/4 = 6.7, 1/9 = 8.1 (increase, predicted would have been ~1.3 based on dosing)
Mg 1/4 = 1300, 1/9 = 1040 (drop)

@Gareth elliott @Cory
So, for my first time dosing and feeling my way -- this seems somewhat as expected. Do you all have any thoughts or guidance for a new doser? Mine below... I plan to retest tomorrow - of course 10% WC with IO Reef Crystals is a new variable! Regardless, I am excited to continue to learn, improve my care for my reef and hopefully have healthy and thriving inhabitants! Thanks all

1. Ca dosing was small and made little to know change, especially with utilization
2. dKH increased as expected
   

When i started 2 part, i got my calcium up with 50ml of solution, was low.
Then i started with the low recommendation, divided that by 12 and made that my hourly dosing. Everyday i test alkalinity at the same time and made adjustments, in my case i added more dosing intervals. End of the week i tested calcium, if that was out of range i added enough to get back into range. Alk stabilized after sometime. Now test weekly and adjust from there.

Edit i also tested magnesium got in range before i started dosing regiment. I use brs 2 part where magnesium is dosed after using up 1 gallon of each ca and alk. I put this on the doser too. Using
Alk total volume(TV)/daily alk used= days to use up alk.
MgTV/days alk is used up.

3785ml/20ml=189 days

580ml/189 days=3.06 ml per day. Sorry i did more math and deleted items but forgot that lol.

Sure there are better methods for putting mg on a doser but thats what i did lol.