Phosphate test kit

[Ruth]

I use Salifert for virtually all of my test and have always found them to be quite reliable............until now.
I usually test my phosphate about once a month and it it usually reads between 0.003 and 0.1 - one of the few Salifert test I have found to use colour strips that you have to match up.
Anyway I purchased a Hanna colorimeter to test for phosphates and just cracked it open today. Imagine my surprise when I got a reading of 0.23????? WTH - so I did both tests again and got the same results. Holy cow this is a huge difference. No wonder I am having trouble with SPS in this tank and have moved most of it out. I started this tank in October with fresh live rock and it is bare bottom. The only thing that I can think of that is adding PO4 to my tank is frozen mysis that I feed daily as my Moorish Idol loves it. I always thaw the little cubes on some paper towel and then add them to tank water before I feed. I am going to try rinsing them really well before I add and see if this starts to bring it down. Needless to say some large water changes coming up this week!

[StirCrazy]

Ruth, the hanna page said the smallest increment that could be read with there phosphate kit was 1ppm how are you getting 0.23?

Steve

[Ruth]

Steve the gizmo is a Hanna HI 93713 and it says it can read PO4 in water, wastewater and seawater in the 0.00 to 2.50 mg/L (ppm) range.

[StirCrazy]

Originally Posted by Ruth

Steve the gizmo is a Hanna HI 93713 and it says it can read PO4 in water, wastewater and seawater in the 0.00 to 2.50 mg/L (ppm) range.

Oh so it is an electric one.. hmm do you know if it will read organic phosphate? the test kits we get will only read inorganic phosphate so if that one will read organic phosphate it might explain the higher reading.

Steve

[christyf5]

Hey I don't mean to change the subject but I just wanted to say good idea on thawing the frozen food on paper towel!! Love it!!

Also where'd you get the phosphate meter doohickey ?

[Ruth]

Oh man Steve and I failed chemistry or darn close - plus it been a year or two. On reading the instruction it gives you two different calculations - one is for P205 and the other is for just P. Maybe you know what hat tests for. The other clue it provides is (PO3/4 In this formula the 3 is above the 4 with a - sign behind it)

[Ruth]

Christy I ordered it out of the States from a guy on the zeovit site. Next time I come down (or swim down) to visit my family I will bring it with me and you can try it out!