Hanna Checker Phosphate LR (HI713) or Phosphorus ULR (HI736)?

[Sailfish]

Hi!

 

I was just about to order the Hanna Checker Phosphorus ULR, from eBay. I wanted to check if Hanna had come with any new models that I could purchase at the same time, to save on shipping cost.

 

Apparently, they now also offer a Phosphate Low Range (HI713).

When I decided to go for the Phosphorus ULR (HI736) model, Hanna only offered the Phosphate HR (HI717) and that.

Now, that there are three different models to choose from, what model should I go with?

What model will be most useful in our reef hobby?

[ghostgr]

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[seabass]

Model - resolution, reading accuracy (± % of reading)

• HI736 - 0.003 ppm, ±0.015 ppm (± 5% of reading)
• HI713 - 0.01 ppm, ±0.04 ppm (± 4% of reading)
• HI717 - 0.10 ppm, ±1.0 ppm (± 5% of reading)

All specifications have been converted to ppm of phosphate (phosphorous ppb x 0.003066 = phosphate ppm)

 

 

They offer ultra low range, low range, and high range checkers. So the HI736 is still the one you want.

[jservedio]

Even though it is less convenient, the HI-736 is so much better - as Seabass described it is more than twice as accurate. The reason it is less convenient is because it reads in phosphorus instead of phosphate, so you have to use the following formula to convert.

 

[HI-736 Reading] * 95 / 31 / 1000 = PPM Phosphate

 

You can always just multiply by 3 and move the decimal point over for a quick and easy reading that is still more accurate than the HI-713

[seabass]

An easier formula is simply multiply the result by 0.003066 (or 0.003 as a close estimate).

 

I've found it just easier to think about it in terms of ppb of phosphorous. The target is a nice and even 10 ppb (about 0.03 ppm phosphate). Isn't that much easier than doing math? It might be more even convenient than seeing the reading in terms of phosphate.

[seabass]

However, you won't really get that kind of accuracy. There are a lot of variables that will make your results vary (particles in the water, smudges and/or scratches on the vial, undissolved reagent, spilled reagent, reagent left in the packet, etc). The thing is, it will give you a decent idea of where the water's phosphate level is at.