Different readings from different brands of Calcium test kits

[bluecheese]

I just tested my water with a Red Sea Pro Calcium test kit, I got a reading of 450, which seems very high. I keep my calcium level, through BRS 2-Part at 430.

I previously used Aquaforest test kits, but I was running low on reagent, which is why I bought the Red Sea Pro kit.

I tested the water with my Aquaforest test kit, and got a reading of 390.

I tested again with the Red Sea and again got a readiing of 450.

Tested again with Aquaforest, and got a reading of 390.

So, which should I go with? I got the Red Sea test because I had read they are supposed to be more accurate. But a difference of 60 between the different brands seems like a pretty wide margin.

Any suggestions?

 

[Icryhard]

Either go for salifert or RedSea. Their test kits work the best and have the most positive feedback. There are some test kits which are “more accurate” than others, but I wouldn’t start mixing salifert and RedSea. Pick one and stick to it.

 

[exnisstech]

Split it in the middle and you'll be right about where you want to be
EDIT FWIW I use salifert. I don't consider calcium critical enough to warrant two test kits like I do alk.

 

[bushdoc]

I actually like Aquaforest and found their Ca and Alk in sync with Salifert tests.( Mg is a bit iffy though)
Aquaforest test kits include standard solution, so you could test it with both Red Sea and Aquaforest and find your answer.

 

[bluecheese]

I actually like Aquaforest and found their Ca and Alk in sync with Salifert tests.( Mg is a bit iffy though)
Aquaforest test kits include standard solution, so you could test it with both Red Sea and Aquaforest and find your answer.

Thats a good idea. I'm going to try their standard solution in a little bit and report back.

 

[Spare time]

To be honest it really doesn't matter. Calcium is fine as long as it's within a range That's acceptable and both of those are fine numbers. If it were me I would probably raise the calcium a little bit just so that if the aquaforest is more accurate, it's less close to the borderline

 

[Randy Holmes-Farley]

FWIW, 450 ppm calcium is not "very high".

I recommend calcium to be 400-550 ppm.

The exact value is not very important since it is not a limiting factor for coral calcification the way alkalintiy is.

 

[bluecheese]

FWIW, 450 ppm calcium is not "very high".

I recommend calcium to be 400-550 ppm.

The exact value is not very important since it is not a limiting factor for coral calcification the way alkalintiy is.

So I'd be ok just going with the Aquaforest reading of 390, and adding the appropriate amount of calcium 2 part to bring it up to 430?

BTW, my Alk was 8.5 using a Hannah checker. I brought it up to 9.0 using the alk 2 part.

 

[Randy Holmes-Farley]

So I'd be ok just going with the Aquaforest reading of 390, and adding the appropriate amount of calcium 2 part to bring it up to 430?

BTW, my Alk was 8.5 using a Hannah checker. I brought it up to 9.0 using the alk 2 part.

That seems like a fine plan since any of the test results will still be OK with a 40 ppm boost, IMO.

 

[bluecheese]

That seems like a fine plan since any of the test results will still be OK with a 40 ppm boost, IMO.

Going back to your earlier reply, you think keeping the Calcium above 400 will be beneficial, as opposed to chasing numbers keeping the calcium at exactly a certain number (430 in my case)?

 

[Randy Holmes-Farley]

Going back to your earlier reply, you think keeping the Calcium above 400 will be beneficial, as opposed to chasing numbers keeping the calcium at exactly a certain number (430 in my case)?

I do not think anyone can notice a difference in coral health between 390 and 430 ppm calcium, but it's a fine thing to do, and eventually if it got low enough and alk high enough (if it did), calcium might limit calcification.

 

[bluecheese]

According the BRS calculator, for my 115 gallons of total water, to add 40 of calcium it will be 470.83 ml or 15.92 fl oz. Does that sound right?

 

[Randy Holmes-Farley]

If this is my recipe #1 (BRS sells this as their soda ash two part recipe), then that is correct.

Here's a better calculator (e.g., has more products):

Reef Chemistry Calculator

 

[GuppyHJD]

FWIW, 450 ppm calcium is not "very high".

I recommend calcium to be 400-550 ppm.

The exact value is not very important since it is not a limiting factor for coral calcification the way alkalintiy is.

I test my Calcium with a salifert test - 450.
I take water to LFS and they use Red Sea - 390
The ATI ICP results show 368

If I want to add a second test kit besides the Salifert, which do you recommend?