what do you use to test phosphate and why?

[Ptyochromis]

I use red sea tests, because I like guessing games.
But mostly because I'm cheep.

1ppm = 1/1000000.0 or 1x10^-6
1ppb = 1/1000000000.0 or 1x10^-9
1ppt = 1/1000000000000.0 or 1x10^-12
(Source: My old chem textbook.
Nivaldo J. Tro. "Chemistry: A Molecular Approach second edition")

so 15ppb is .015ppm

 

[Acronic]

Yes, that would be the case if we were converting po4 in ppb to po4 in ppm. But in order to convert phosphorus into phosphate, we must multiply by 3.066, then convert to ppm

 

[jda]

Salifert. If it is anything other than "clear," then that is all that I care about. You can usually tell all that you need to know with your eyes.

I don't know if any of these kits are precise enough to really make a difference anyway.

 

[Dugless]

I think either of the Hanna checkers are sufficient enough in their precision. It isn't difficult to find yourself chasing numbers, but in the end I like to put more emphasis on overall coral color and growth with a goal towards stability. I like to consider my testing results as more of a guide rather than exact data that needs to be met.

 

[trueblackpercula]

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.

I don't understand if there is a question here for me as you are clearly stating exactly what i posted. the algae consumes it faster then we can test for it.
but you already know this.

 

[LoJack]

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

Right, but I'm not striving for ULNS. I prefer slightly detectable nitrate, and very slightly detectable phosphates.

I only test for phosphates when my corals tell me too anyway. If I see a problem with algae, I test "¦ and then adjust as necessary with GFO or altering feedings. Its just an indicator to see how far I've strayed.

If it reads at anything under .08 I don't bother doing anything "¦ because IMO in an SPS tank thats completely fine.

For a long time people were going crazy with ULNS "¦ 0 Nitrates, 0 Phosphates "¦ and then every thread on here was about faded colourless SPS.

Now we target slight slight amounts to keep the corals fed.

My strategy is simple. Feed as much as possible without spiking my phosphates. If algae shows up "¦ get phosphates down a bit but continue with what I'm doing.

 

[64Ivy]

I have the Hanna ULR checker also (as well as a Salifert kit) but what I've been doing lately is sending my water out to a lab [AWT] for a monthly testing. Why? I simply do not trust hobby grade meters or kits for anything other than pH, temp, alk, and maybe Mag. Definitely not P04; and the variance I get between the Hanna and the lab results can be a lot more than +/- 0.04 mg/L. Yes, I realize the lab can be wrong too but, if so, at least they've been consistently wrong.

In this hobby, that's a win.

 

[Acronic]

Agreed. Overall the stability matters more than the number.

 

[toothman]

I have the Hanna ULR checker also (as well as a Salifert kit) but what I've been doing lately is sending my water out to a lab [AWT] for a monthly testing. Why? I simply do not trust hobby grade meters or kits for anything other than pH, temp, alk, and maybe Mag. Definitely not P04; and the variance I get between the Hanna and the lab results can be a lot more than +/- 0.04 mg/L. Yes, I realize the lab can be wrong too but, if so, at least they've been consistently wrong.

In this hobby, that's a win.

Have you ever considered purchasing faunna marin reference water to compare it to your test kits. Worked well for me.

 

[jscarlata]

i've come to realize that chasing these numbers at the stage my tank is in is pointless...i'm going to do what many have realized...run the tank, feed the fish, when algae appears or cyano comes back, test and adjust with GFO/GAC. I'm also now testing out an Algae Scrubber using my 2nd drain line, and it is working quite well at growing Algae.
I think my newbie mistake with SPS was trying to have the same #'s that much more mature tanks have, tanks that are full of corals and that matured to be stable within those parameters...your numbers or his numbers may not work for my tank (especially while it is young), so why should i try to copy them...I'm on a new track now, i have a solid understanding of what i need to do, all i need now is the $ to get some SPS frags and start over. i really like my rockwork and layout now and i am QT'ing more fish....i was close to giving up, but i have found new motivation to try SPS again..

 

[dowtish]

Hanna for me as well. The whole 0.4 +- issue doesnt matter to me at all. As long as I get steady readings I'm fine with it. My tank has consistently given me readings of 0.08 for months at a time before and my corals never looked better.

 

[madweazl]

I have the Red Sea Pro kit and it's ok at best but I rarely test for anything after initial setup anyways.