[Delphinus]

I use a Hanna colorimeter for phosphate and the Pinpoint for nitrate, so I might have a good perspective.

To be honest, I'm not truly thrilled with either in that they are both finicky and fussy in their own unique ways.

The Pinpoint probe is very delicate and requires calibration for EVERY reading. And prolonged exposure to RO/DI ruins them - so don't leave the probe soaking overnight for example. It takes a while for the readings to settle, and even then sometimes bumping or swirling will get you a different result. The nice thing about the Pinpoint though is that you get calibration fluids so if you're ever doubtful of a value you can test against a calibration fluid as a reference sample. Also the tester has two ranges, 0 to 10 and 10 to 100 (each requiring its own calibration), so sometimes you end up being right on the border and you get an "underrange" error on one and an "overrange" error on the other (although I guess if it happens, you can safely assume the value is somewhere very close to 10).

The Hanna on the other hand gives you readings to an accuracy of "0.04". This means, say if you have PO4= 0.00, with enough readings you'll get it to tell you 0.00, 0.01, 0.02, 0.03 and 0.04.

My experience may be more sour than most because with both units I had to go through this whole "how do I know if this thing is working right?" phase and nobody I knew had these things so I was on my own. As it turns out, my nitrate monitor WAS faulty, and had to be sent in for repair (they were pretty good about taking it and fixing it - Pinpoint is a good company to deal with that way). Hanna on the other hand is a huge multinational corporation and although they do have technical support, you're just a number to them (and a number who's only bought one of their units at $200 or whatever), and they get all testy if you're calling say CANADIAN technical support but your unit was sold out of a U.S. based wholesaler. Well... testy might be too strong of a word, but I found it became an issue with me and the questions I had. In the end, I found another Canreefer with the same unit and we took a whole bunch of tests on our tank waters and we basically came up with the same variances. Bottom line, the instructions do say that the accuracy is "plus/minus 0.04" so if the numbers you get do not exceed a range of 0.04 then it's working as advertised. Every now and again I do get a real wingnut of a reading but I chaulk that up to user error. It's not the easiest thing in the world to work with.

On that, here's what I found. You have to empty these little powdered reagents into a glass vial that has an opening of barely 1/4". You fold the envelope into a diamond shape so that the powder funnels in but invariably, there is a bunch of powder that has glommed together into a clump. So you take your envelope and start tapping it onto the glass, and invariably, some falls into the vial, but some misses. Then you're wondering, "I know they say there's more than enough reagent to complete the reading, but did I get enough of it? Well I probably did? But ? I don't know really really for sure?" And so on. And things like fingerprints on the glass, or little tiny bubbles, all affect the reading, so you end up having to be a little anal with your methods.

Anyhow, the sum total of this is ... Pinpoint is a slightly nicer company to work with, and we're their target market, but their product is a little more delicate. Hanna's product is a little more scientific-grade, but not as nice to work with (in my opinion), and we're a tiny drop in the ocean as far as their market is concerned. As for the validity of the numbers they produce though, one is probably just as good as the other, and while I may complain about them, they still beat out colour-comparison-to-a-chart test kits because I find the colours never really match 100% (ie., is intensity or saturation more important than hue? I never know with those things). So from that perspective, either Hanna or Pinpoint are a huge step up.