Phosphate

I have read a few threads in the past and even started one aksing about the hanna checkers for obtaining phosphate levels. It seemed like many people just started to use them when I was asking around about accuracy and ease of use.

So what is the verdict how are the hann checkers for phosphates? Do you find them to be reliable and accurate or do you get a different result everytime you test?

Also for my reef what one do I want the phosPHATE low range or high range or the phosPHOROUS low range or high range? I have never checked phosphate levels in my reef and just started GFO so figured getting a test kit is the only way I will be able to tell if it is working and when it is exhuasted

 

I've been using the phosPHATE checker (low range) for quite a while now and have found it to be accurate; no complaints here.

Certainly yes, the phosPHOROUS checker will be more accurate, but it's also not as convenient to interpret.

This guy is all you should need: Hanna Checker Phosphate PO4 Colorimeter - Bulk Reef Supply

 

Thanks evolved. The reagents seem qutie expensive but the color testing is terrible with all the other tests.

Do you use the checkers for any otehr test like nitrate, alk, or ca?

 

Just a Hanna checker for phosphate, as no liquid test kit can give you even a remotely decent low-range test. I don't let my tank run higher than 0.02.

The reagents might be a bit expensive, but it'll take you a while to go through them; it's not a test you'll do but once or twice a month.

I use Salifert for all my other tests; they're easy to use and reliable.

Do note, the Hanna checker for Ca isn't all that great; the Alk is fine however, but Salifert kits are still cheaper.

 

I agree with evolved on all points except the phosphorus checker. I think it is worth the extra precision. Just multiply by 3.066 and divide by 1000. For all intents and purposes though, you can just simplify and multiply by 3 then divide by 1000. Heck even I can do that in my head ;p

Also as far as accuracy goes, I have not sen idependent testing so, tough to confirm the manufactures numbers, but according to their numbers the accuracy is quite good.

 

Hmm a little math is simple. I wonder what the difference in accuracy is between the two.
What exactly is the difference between the phophate and phosphorous? Does the phosphrous check measure all phosphorous where the phosphate only measures orthophosphate?
Also is it orthophosphate that I am concerned with or should I be concerned with all forms of phosphorous?

 

They measure the same thing, just scaled differently. The P reader, reads parts per billion, the PO4 reader, reads parts per million. Hence the divide by 1000. The 3.066 is just the ratio phosphorous to phosphate. I.e. the atomic weight of O is 15.999 and the atomic weight of P is 30.974. So, the weight of PO4 is 4x15.999 + 30.974=94.97 mg/L (where for our purposes, mg/L is equivalent to ppm). Of this 30.974 is phosphorous, so 30.974/94.97=3.066 mg/L.

For all I know, it could be the same device, just with different readings, but according to the Hanna documentation and sales reps, the phosphorous checker is more accurate by .01ppm (i.e. reading +/- .03 ppm vs reading +/- .04ppm).