Help with calcium dosing. 0 ppm?

[Whysohigh]

I recently started dosing calcium and can not get seem to get any readings over 70ppm. Is this normal?
About my tank:
180 gallon with 45 gallon sump
Massive candy cane colony, frogspawn, more larger lps and softies.
Alk is staying around 8.6-8.9
Salinity 1.024
Temp 79°F
Ammonia 0
Nitrate 0
Nitrite 0
Phosphates .01
RO/DI water 0ppm
PH 8.2

I tested a handful of times before dosing with my Salifert calcium test kit. I couldn't believe I was at 0 ppm calcium. The calculator said to add 1000ml to bring it up from 0 to 50 (not raising it more than 50 as recommended). I decided to play it safe and added only 100ml the first night and tested 24 hours later and was still at 0. The following are my next 5 days of dosing, bringing us to today, I tested and then dosed...
Day 2 tested at 0, I dosed 100ml
Day 3 tested at 70, I then dosed 500ml
Day 4 tested at 30, dosed 1000ml
Day 5 (today) tested at 0 (double checked) dosed 1050ml.

Are my corals eating that much? I've gone through almost a gallon of calcium in 5 days and before my last 1050ml dose tonight it tested 0 after dosing 1000ml 24 hours prior. I don't get it.

 

[pandagobyguy]

It shouldnt be that low.... sure you are doing the calcium test correctly? If it is titration, you should continue dropping in reactant until color change is permanent.

What form of calcium are you using? A two part additive?

 

[Flippers4pups]

Got to be a bad test kit or testing error.

 

[Finhead]

I agree has to be a bad test kit, I'd stop dosing anything and get a new test kit. Red Sea or Aqua Forest are really good kits.

 

[Flippers4pups]

Calcium and alkalinity are linked. With a alkalinity at 8-6 to 8-9, there's no way your calcium could be as low as 70!

Read this:

http://www.advancedaquarist.com/2002/11/chemistry

Bad kit or testing error.

 

[Whysohigh]

I'm using 2 part from bulk reef supply. I'm certain I'm using the kit correctly. I've stared at the directions each time I used it. I do have a friend coming over tomorrow with his red sea kit to test my water so I'll reply afterwards. Thanks for the responses.

 

[Finhead]

I'm using 2 part from bulk reef supply. I'm certain I'm using the kit correctly. I've stared at the directions each time I used it. I do have a friend coming over tomorrow with his red sea kit to test my water so I'll reply afterwards. Thanks for the responses.

What test kit are you using?

 

[Randy Holmes-Farley Verified Community Expert]

There’s no chance at all that a reading of 70 ppm is correct. Are you sure you are not reading the syringe backwards?

 

[Whysohigh]

It's the salifert test kit. I'm 100% sure I'm using it correctly. I use the same brand to test alkalinity and magnesium (yes I know the colors are reversed) even though I use the instructions I have them memorized. 2ml of tank water, 1 scoop of ca1, 8 drops of ca2 add ca3 until color change. No matter how many times I do it I get the same results. Like I said I have a friend coming by to use his kit and I've messaged the company that sold me my kit. Hopefully today I get things sorted out.

 

[Randy Holmes-Farley Verified Community Expert]

So you used just a very small portion of a syringe of titrant to get to the color change? I’m just saying this because some people read the Salifert syringe backward and would get a very low value when it is actually fine.

 

[Whysohigh]

Test kit is bad. We used another salifert and red sea. Both say I'm at 500ppm. So we kept retesting each time using a different reagent from my kit. Once we used the CA 3 from my kit it read zero.
Good call to everyone that suspected the kit, thanks for everyone's help.

 

[Fishfinder]

I'm surprised it's only 500

 

[Whysohigh]

So am I. Everything looks really happy though. My friend commented on my corals and their appearances from the last time he saw them last week.

 

[Whysohigh]

So you used just a very small portion of a syringe of titrant to get to the color change? I’m just saying this because some people read the Salifert syringe backward and would get a very low value when it is actually fine.

I did that when I first got the kit. My first test I did on a fresh batch of mixed saltwater I had ready for a water change. Read the syringe backwards and got 50 ppm lol. Realized my mistake, felt like an idiot, lesson learned.

 

[Randy Holmes-Farley Verified Community Expert]

Glad things are under control!

Happy Reefing.

 

[Whysohigh]

This may be a topic for another thread, but out of curiosity at what point will calcium and alkalinity start to cause problems if it's too high? Obviously 500ppm of calcium isn't the magic cartographic number.

 

[Randy Holmes-Farley Verified Community Expert]

This may be a topic for another thread, but out of curiosity at what point will calcium and alkalinity start to cause problems if it's too high? Obviously 500ppm of calcium isn't the magic cartographic number.

Normal seawater and nearly any reef tank is already supersaturated with respect to calcium carbonate. As alk and calcium and pH and temperature all rise, it just gets worse and worse and more likely to precipitate.

FWIW, a rise of 0.3 pH units is a big effect, the same as doubling alk or calcium.