View Full Version : red sea po4 test
timrandlerv10
03/01/2007, 06:53 PM
ok...so i put 1 ml of tank water, 11 ml of ro/di water.
i mixed, shook, waited as directed.
i checked the color, and its 0.1...but since we did 11 ml of ro water, does that mean the real result it .01 or 1.0?
its times like these that directions better than on the back of the card would come in handy...
thanks,
tim
E-A-G-L-E-S
03/01/2007, 06:53 PM
not to mention, how accurate is the reading anyways...
Randy Holmes-Farley
03/02/2007, 05:55 AM
I've not used it so I cannot say for sure, but if you followed the directions to dilute and they did not say to correct for a dilution step, then I wouldn't.
timrandlerv10
03/02/2007, 10:08 AM
they did talk about it, but it was in that directions sheet that i no longer have... :(
in general, does dilution make the number bigger or smaller?
Randy Holmes-Farley
03/02/2007, 11:50 AM
Dilution (with fresh water) makes the actual concentration smaller, so if you test a diluted solution, you multiply back up to get the original concentration, which was higher than the tested sample.
timrandlerv10
03/02/2007, 12:08 PM
so my .1 was actually 1.2?!
Randy Holmes-Farley
03/02/2007, 12:14 PM
As I mention above, if the directions told you to dilute, then you likely would not multiply. Without the directions, you can't know. :D
timrandlerv10
03/02/2007, 12:24 PM
from what i remember, they said 1) do the test normally, read off chart OR 2) you could dilute 11 to 1, read off chart, and [insert math operations] by 12.
you can see how the whole thing falls apart without that one math operation...
they should have that on their website...(or i shouldnt lose it).
HEY...back to work...find a drug for spondalytic arthropery please. thanks.
tim
jdieck
03/02/2007, 12:38 PM
The normal test for values below 1 ppm do not require dilution so you fill the vial to 12 ml mark, add 8 drops of reagent A (Sulphuric acid) mix, Add two drops of reagent B (Glycerol) mix and wait 2 minutes for the color to develop then compare to the color chart (View vertically trough the solution) read the result in ppm PO4 ion.
For concentrations above 1 ppm the accuracy can be increased by dissolving the sample. as mentioned above use 1 ml of aquarium water and add 11 more of distilled or RO/DI water to the 12 ml mark, perform the test as described above read the result and MULTIPLY the result by 12 to obtain the concentration of PO4 ion in the sample water.
You can get the instructions from the following link:
http://www.redseafish.com/languages/95/pdf/141.pdf
Enjoy!
jdieck
03/02/2007, 12:40 PM
<a href=showthread.php?s=&postid=9370202#post9370202 target=_blank>Originally posted</a> by timrandlerv10
ok...so i put 1 ml of tank water, 11 ml of ro/di water.
i mixed, shook, waited as directed.
i checked the color, and its 0.1...but since we did 11 ml of ro water, does that mean the real result it .01 or 1.0?
its times like these that directions better than on the back of the card would come in handy...
thanks,
tim
That reading is 1.2 ppm PO4
gateb
03/02/2007, 04:50 PM
I bought Red Sea PO4 test a while back because everyone seemed to be out of the Salifert ones at the time. The Red Sea test perpetually gave a light shade of green (the .1 color) before I even put the second set of drops in for as long as I've been using the test. I became suspicious of the results and decided to use a Salifert test that I bought a month or so ago when I saw that online vendors had them back in stock and I got a zero reading. Needless to say, I don't trust the Red Sea test anymore. Maybe I had an old or bad kit.
boxfishpooalot
03/02/2007, 05:03 PM
Their ammonia test kit always shows a color of green too. Which is surprising because at .25ppm ammonia everything would be dead....
jdieck
03/02/2007, 06:49 PM
In my experience Phosphate kits are not accurate enough below 1 ppm to give a precise reading (I have tried Red Sea, Salifert and Hach). In lieu of that I really treated the results as a kind of Yes/No detection. You detect something then you have Phosphate and act. You do not detect anything, then you are OK.
In other words the number might not be meaningful.
Since then I use a Hanna colorimeter which gives a bit better accuracy.
Randy Holmes-Farley
03/03/2007, 09:10 AM
In my experience Phosphate kits are not accurate enough below 1 ppm to give a precise reading
Did you mean 0.1 ppm, or do you really mean 1.0 ppm?
IME, the Hach kit is accurate between 0.1 and 1 ppm. :)
jdieck
03/03/2007, 11:01 PM
<a href=showthread.php?s=&postid=9382611#post9382611 target=_blank>Originally posted</a> by Randy Holmes-Farley
In my experience Phosphate kits are not accurate enough below 1 ppm to give a precise reading
Did you mean 0.1 ppm, or do you really mean 1.0 ppm?
IME, the Hach kit is accurate between 0.1 and 1 ppm. :)
Sorry, I missed the dot. Below .1 ppm is what I have seen were most innacuracies are. Because I try to keep PO4 below 0.05 I treat any reading as "too much" and no reading as probably OK although sometimes; as you had mention before, no reading may not mean much specially if algae is consumming it.
Randy Holmes-Farley
03/04/2007, 08:02 AM
Yes, I tend to agree. :)
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