Calcium Tests

[DaveJ]

Randy,

A quick question, well hopefully so.

If a test is done on a sample of water and the test is designed to read free ca ions only and gives a reading of say 320. Then another test is done with test kit designed to read all calcium, including calcium carbonate etc.. and gives a reading of 440. Which is the better reading to go off of for our tanks? Do corals and other critters like clams etc use only free ion calcium or do they also utilize the other forms of calcium in the water?

When we are shooting for calcium in the 400-440 ppm range for our tanks, is that total or free ion? Or does it matter?

 

[bertoni]

Calcium carbonate is present in water only as unsettled sand. I don't know enough about how calcium test kits to know whether some part of the testing procedure might detect the presence of such sand, but the amount is going to be negligible in any normal situation.

The test kits are designed to measure ionic calcium, and any calcium that's bound up would be measured only as a side effect, if at all. I don't think there's going to be much of that, either.

 

[DaveJ]

<a href=showthread.php?s=&postid=11807676#post11807676 target=_blank>Originally posted</a> by bertoni
Calcium carbonate is present in water only as unsettled sand. I don't know enough about how calcium test kits to know whether some part of the testing procedure might detect the presence of such sand, but the amount is going to be negligible in any normal situation.

The test kits are designed to measure ionic calcium, and any calcium that's bound up would be measured only as a side effect, if at all. I don't think there's going to be much of that, either.

So you are saying that if one test is designed to measure ionic calcium and the other total calcium, including any bound etc.. that they still should relatively close to each other, assuming both were equally accurate and sensitive?

 

[bertoni]

That would be my expectation, unless the tank were being dosed with something fairly unusual, like calcium EDTA.

 

[Billybeau1]

I have not seen any hobby grade test kit differentiate between calcium ions only, and total calcium.

Seems to me they are the same thing.

Lets see what Randy says in the AM.

 

[DaveJ]

Bump for Randy's Input