what do you use to test phosphate and why?

M

marthin

New member
Hi people..
I would appreciate if you could state which tests you use and why for phosphate. The tank is turning into a sps city with a space full of sun corals
I have used salifert, D_D, Elos.. mostly ended up with very low reading and lots of algae
now that I'm starting again and wanna wing it a bit 'marthin-style' I need a good test kit.
All comments are very welcome
 
I use the milwaukee because its just so much easier to deal with. i have tried almost every test kits out on the market and it has just always been a pain.
 
I use my eyes. When I get some algae growing on the sand I run more gfo. If I get brown/green stringy looking algae I stop running gfo because I'm now too clean...
 
hanna here, as well. i use the phosphorus tester.
more accurate than colours..
and i think just more accurate, period..
 
Hanna checker ULR is excellent. is measures in PPB! in ULNS you must measure it. 0 phosphate is bad bad.
 
marthin said:
Hi
I have used salifert, D_D, Elos.. mostly ended up with very low reading and lots of algae.
Click to expand...
The algae is masking the true PO4 readings,remember the consume it that's why you were getting low reading. Most test kits today are all good. I have used saltifirt and elos and lamotte
 
I use the Milwaukee "Martini" low range photometer.
Curvets have larger openings than the Hanna.
I have always had problems with the low range color distinctions
and like above I get a #.
 
Hanna checker for me.

I don't care for the Hanna checkers usually. I use ELOS tests. But when it comes to phosphates Hanna is just too quick, easy, and accurate to overlook.
 
LoJack said:
Hanna checker for me.

I don't care for the Hanna checkers usually. I use ELOS tests. But when it comes to phosphates Hanna is just too quick, easy, and accurate to overlook.
Click to expand...

Really? the hanna meter has a variance of +- .04...if SPS tanks shoot for a phosphate # around .05-.06, how could you possibly get there using this meter? i have one as well, but after getting so many varied readings, and then factoring in the variance which could go either way + or -, i didn't see it being worthwhile...
if you get a reading of 0, it COULD be .04...if you got a reading of .04, you could be at 0 or .08!!!...idk, is this as accurate as these tests get? i recall doing a lot of searching online this summer for a better meter at a reasonable price and i gave up...
i think if you are really high and need to get into a better ballpark with phos, then this can get you close, but no way can i see how it can zero you in on the magic number...
i haven't tested phos in a while, and i tested last night at .14...so i know i needed to change up/increase my gfo...but i dont feel like i can rely on this device to get me from say .1 to .05 accurately
 
That's why I shoot for 0. If it's +- .04 and I have 0 even if it really is .04 my tank will most likely be doing just fine. I use it as a means to check trends and you do that by reviewing a wide range of tests following patterns. If I see my phosphate is trending up I change my GFO.
 
If you are worried about the resolution variance of the low range phosphate kit then you should switch to the ultra low range phosphorus kit (which is really what you should be using for chasing uln numbers anyway) It has a variance of +-5PPB. Acurate enough to make a sound decision with and lets be honest, what else are you going to use? Tritration kits are laughable for po4 reading. By the time you factor in all the variables for those kits the variance can be astronomical and unknown (ambient lighting, personal judgment of colors, discrepencies between the color on paper versus a liquid...)

The ultra low range kit from hanna gives you a straight forward numerical value in ppb. Converting that number to ppm is simple.

Lets say you do your test and the value is 15ppb.

15 x 3.066 / 1000 = 0.0459ppm

Now, the kit is +-5ppb, so

20 x 3.066 / 1000 = 0.0613ppm

So in conclusion, to be able to read down to within 0.02ppm is more than acurate enough to make a sound decision. If you need more acuracy than that, well, I think spectrographs go for a cool $16000
 
Last edited:
trueblackpercula said:
The algae is masking the true PO4 readings,remember the consume it that's why you were getting low reading. Most test kits today are all good. I have used saltifirt and elos and lamotte
Click to expand...

How do you figure? The phosphate is in the water. The algae sequester and remove it from the water column. The phosphate they have sequestered is no longer available for use by other organisms, unless said algae decomposes/gets eaten.

By that logic you could say that every organism in your tank is masking true phosphate readings.

In the end you really only care about what's dissolved in the water and not so much about every thing living and nonliving in the water.
 
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