Calcium Checker - Deionized water?

[rbarr110]

So I have been using my Hanna Calcium checker for a while now and over the last 10 months there has been minor drops in my calcium. I manually dose, infrequently, as not much calcium appears to being consumed.

After doing a check last night, I began wondering if my practice of using RODI water in place of deionized water (as noted in the instructions) maybe giving me inaccurate results?

Is RODI water not appropriate for the test? (DI resin should make it deionized, yes?)

 

[Brad Miller]

RO is reverse osmosis and takes a lot of things out of the water.
DI is Deionized water.
Using rodi for the Hannah checker is the preferred way for us to use the tester, since this is what we all have on hand.
The use of DI is acceptable since it does remove things like calcium and is cheaper.

 

[Waynerock]

I get a jug of distilled water from CVS and use. Seemed to never have an issue. I swear on the video they put out on YouTube showing how to use it he was using and said something about using distilled.

 

[rbarr110]

I get a jug of distilled water from CVS and use. Seemed to never have an issue. I swear on the video they put out on YouTube showing how to use it he was using and said something about using distilled.

I was looking around the Hanna site and found that they recommend deionized water -OR- steam distilled water. I picked up a gallon of steam distilled over the weekend and tested that against my RODI test results. Results were very close, RODI was at 463 ppm, the distilled was at 448 ppm. The difference could be either the rodi vs. distilled and/or my measurement of fluids. Either way, very similar results and well within acceptable tolerances. Only downside with using your personal RODI water that I can see is when the unit becomes less efficient it could skew results.

 

[ajhudson15]

I tested rodi vs distilled vs a red sea kit and the distilled came out closer every time

 

[Hanna Instruments]

So I have been using my Hanna Calcium checker for a while now and over the last 10 months there has been minor drops in my calcium. I manually dose, infrequently, as not much calcium appears to being consumed.

After doing a check last night, I began wondering if my practice of using RODI water in place of deionized water (as noted in the instructions) maybe giving me inaccurate results?

Is RODI water not appropriate for the test? (DI resin should make it deionized, yes?)

The HI758U Marine Calcium Checker HC® uses a 100 to 1 dilution for analysis and thus requires deionized or distilled water absent of calcium to function correctly. Calcium can be found in many freshwater sources and this any amount present in the water used at the C1 phase can cause false high readings. In addition, many hobby grade reverse osmosis deionized water systems may not adequately remove calcium. This can vary based on the types of filters used, their effectiveness and frequency of replacement. We recommend using deionized water with low conductivity or pure vapor distilled water commonly found in most pharmacies. It is important to make sure you are using the new HI731339P volumetric pipette to administer saltwater sample to the cuvette. Any increased or decreased sample size will result in inaccurate readings.
Never use tap water to clean your cuvettes. This is especially important for the HI758U Marine Calcium Checker as calcium is commonly present in tap water and residual amounts present in the cuvette will elevate results produced by the Checker. Our HI98703-50 Cuvette Cleaning Solution ensures the glass cuvette used for colorimetric measurements remains clean and free from imperfections.
Calcium Checker Troubleshooting Tips
1. Never rinse your cuvettes with tap water or saltwater
2. Use pure vapor distilled water from your local pharmacy at C1 phase. RODI water from home filtration units may not be suitable for this test as calcium can easily permeate through your filter membranes.
3. Clean your cuvettes with distilled or deionized water absent of Calcium that is going to be used for C1 phase dilution.
4. Measure out 9 ml of distilled or deionized water for C1 phase
5. Make sure no excess aquarium sample saltwater is on the tip of the pipette. Only administer the saltwater that is sucked into the pipette tip.