Measuring phosphates

[lilchris]

What is the most accurate way to measure your phosphate levels?

[Reefer07]

Accurate phosphate kits like salifert or elos. I'm sure there are another few brands. However, no matter which brand I have used I always find it difficult to read the colors.
Maybe a hanaa instruments photometer or something......?

[tmz]

I use the Hanna photometer and find it relatively easy to use. The digital readouts are a real treat after straining with test kits to distinguish tints of blue.

[tonyf]

^ Same here ... those kits are buggers for old eyes :)

[bertoni]

The meters are easier to read, but it's not clear that they're any more accurate. They might be less accurate. The Hach test kit is a bit easier to read than the Salifert kit, in my opinion.

[HighlandReefer]

I recently bought a Salifert Phosphate Test kit and it showed no levels of phosphate in my system. I have microalgae growing, so one might assume that I have levels above .02. I had inquired about the phosphate test kits myself. Randy uses the Hach Phosphate kit and it seemed to be the cheapest option.

I just bought the Phosphorus, Orthophosphate (reactive) Test Kit, Model PO-19, Color Disc, 100 tests by Hach: http://www.hach.com/hc/search.product.details.invoker/PackagingCode=224800/NewLinkLabel=/SESSIONID%7CAVZWWlUwOHhNakl6T0RZMk5UVTRPVEE1Sm1kMVpYTjBSUT09QQ==%7C

Subtotal: $75.65
Shipping: $15.95
Total (before Taxes): $91.60

[Randy Holmes-Farley]

Did you try using the Hach yet?

[HighlandReefer]

I just bought it online yesterday afternoon. I'll let ya know my results compared to Salifert after I get it. :)

[Wrench]

I use the Hannah colorimeter. IME it has been more accurate than reagent kits. Although I never used the Hach kit.

[Randy Holmes-Farley]

IME it has been more accurate than reagent kits

It may be, but I'm curious how you'd know which values were accurate?

[lilchris]

I have the salifert test kit and the ELOS test kit. I haven't been able to get a reading from either kits. I know I have some levels of phosphates due to the hair algae in the overflow.
I am looking to get this colorimeter http://www.aquacave.com/mi-412-phosphate-colorimeterbr-low-range-by-martini-842.html

Not sure if it will be more accurate than my test kits.

[Randy Holmes-Farley]

While the levels may be low enough so that you are not detecting it, it does not mean the kits are inaccurate. Nor does it really mean there is a lot of value, IMO, in knowing exactly what the levels are at those low levels. As long as the levels are not especially high (say 0.1 ppm or above), the treatments are about the same.

If you have too much hair algae, then there is too much available phosphate regardless of what any kit might show or what the true "level" might be ay any instant, and exporting more phosphate or importing less phosphate is a fine plan to reduce the algae. :)

[Wrench]

<a href=showthread.php?s=&postid=13617209#post13617209 target=_blank>Originally posted</a> by Randy Holmes-Farley
IME it has been more accurate than reagent kits

It may be, but I'm curious how you'd know which values were accurate?

Basically it boiled down to deduction. I was using a few different reagent kits and getting readings between 0 and .1. I was experiencing agonizigly slow growth of hard corals and coraline. A friend lent me his Hannah and the readings were .65. I set up a phosban reactor and cut back on feeding to bring the levels down. As they dropped, my corals growth was accelerated and they colored up as well.

Could I have had a problem with those particular kits? Probably. Is it fair to label them all as inaccurate? Probably not, but it makes logical sense to me that the Hannah was more accurate at least in my case.

[Randy Holmes-Farley]

Well, that's a serious difference (0.65 ppm vs less than 0.1 ppm) that I'm surprised you'd see short of a defective kit.

[lilchris]

<a href=showthread.php?s=&postid=13617587#post13617587 target=_blank>Originally posted</a> by Randy Holmes-Farley
While the levels may be low enough so that you are not detecting it, it does not mean the kits are inaccurate. Nor does it really mean there is a lot of value, IMO, in knowing exactly what the levels are at those low levels. As long as the levels are not especially high (say 0.1 ppm or above), the treatments are about the same.

If you have too much hair algae, then there is too much available phosphate regardless of what any kit might show or what the true "level" might be ay any instant, and exporting more phosphate or importing less phosphate is a fine plan to reduce the algae. :)

If I can't get a reading on any of my kits, then how would I know if my levels are 0.1ppms or above. Do I just assume the kits are accurate and the readings are accurate? I have a few pieces of SPS corals in my system, they are growing but not at the rate that I see other tanks. I know that's comparing apples and oranges. I want to get a handle on my phosphates. I am trying to start w/ my parameters making sure my readings are in within limits and the readings are true. I have a few extra bucks so I thought I would get a really good test kit or colorimeter for phosphates. My Hair Algae is limited to the overflow and on a rock in the refugium. I know I have phosphates, just not sure how much, so I need know how aggressive I should attack the issue. I know i need to get a handle on it. Right now I just have a refugium. I did use GFO in a reactor. I also dosed VSV. Right now I am not doing anything because I am away from my tank. When I get back next week I want to get a hand on this. Just want to make sure I pick the proper method. I also want to start w/ a proper and true reading so I know what I am working with

[bertoni]

The Salifert kit will read down to 0.03 ppm, at least if the kit is working. If the test shows clear water, I'd expect that the tank has less than 0.1 ppm. You could try cross-checking the kit with a Hach, if you're worried, but I suspect the phosphate level is fine. Many algae can grow with phosphate levels that are undetectable by our kits, for a couple of reasons. First of all, our kits detect only orthophosphate, and not any organic forms of phosphorus. Secondly, phosphorus is needed only in small quantities, so the algae often can consume it very quickly as it's released. That's why growing and harvesting a macroalga can help with phosphate control down to very low levels.

If you're very worried, ENC Labs can run a test that I'd trust, although the cost is rather high. Another option might be to try the Hach total phosphorus kit, which should measure most all the phosphorus (not just phosphate) in your water. I haven't used that kit, though, and don't know how safe or costly it might be.

[lilchris]

<a href=showthread.php?s=&postid=13620090#post13620090 target=_blank>Originally posted</a> by bertoni
The Salifert kit will read down to 0.03 ppm, at least if the kit is working. If the test shows clear water, I'd expect that the tank has less than 0.1 ppm. You could try cross-checking the kit with a Hach, if you're worried, but I suspect the phosphate level is fine. Many algae can grow with phosphate levels that are undetectable by our kits, for a couple of reasons. First of all, our kits detect only orthophosphate, and not any organic forms of phosphorus. Secondly, phosphorus is needed only in small quantities, so the algae often can consume it very quickly as it's released. That's why growing and harvesting a macroalga can help with phosphate control down to very low levels.

If you're very worried, ENC Labs can run a test that I'd trust, although the cost is rather high. Another option might be to try the Hach total phosphorus kit, which should measure most all the phosphorus (not just phosphate) in your water. I haven't used that kit, though, and don't know how safe or costly it might be.

I looked up that kit. It was about $75 +shipping. That is why I was going to try the digital meter, a few extra bucks. Are those accurate?

[tmz]

<a href=showthread.php?s=&postid=13620574#post13620574 target=_blank>Originally posted</a> by lilchris
I looked up that kit. It was about $75 +shipping. That is why I was going to try the digital meter, a few extra bucks. Are those accurate? :) I use one. AFter a few miscues, I think I'm getting accurate readings but don't really have a way to check, I did test my newly mixed ro/di slat water and got a reading of .02ppm(withjin the advertised margin of error if I assume my salt mix is really 0. . I find it easier to read. and generally more useful than the Salifert kit I was using but can't really attest to accuracy.

[Todd March]

Terrible translation, but HERE (http://www.mbenassireef.com/?p=25) is a site where an independant German site tested hobby test kits and found Elos to be very accurate. Heads and tails above Salifert, and even beating D&D/Merrick at the PO4 tests...

[bertoni]

The problem with tests like this is that they are seldom well controlled and they often contradict each other. They usually are based on a sample size of one or so. So I tend not to trust them all that much.

[palawan]

The best way is with Hannas low phosphate meter.

[Todd March]

<a href=showthread.php?s=&postid=13621533#post13621533 target=_blank>Originally posted</a> by bertoni
The problem with tests like this is that they are seldom well controlled and they often contradict each other. They usually are based on a sample size of one or so. So I tend not to trust them all that much.

Yeah, I take them with a grain of salt as well. Though this one got my attention, as the differences they found between Salifert and Elos on all the tests they preformed where precisely the differences I have found between Salifert and Elos myself as well this summer (and I had only ONE reference solution)...

Just going by what makes sense for my tank, Elos has been right on the money...

What cinched the deal for me was when Elos read Salifert's own reference solution (came with thier alk test kit) right on the money, but the Salifert kit has shifted so bad (90 days old) that it read the reference solution 4 dKH higher than it was...

I know Salifert has a lot of fans around here (I used to be one), but the kits have just gotten so bad that they don't even last a few months now before the regents go bad and the marking on the syringes rub off... At some point, all the mighty fall...

[Todd March]

<a href=showthread.php?s=&postid=13621540#post13621540 target=_blank>Originally posted</a> by palawan
The best way is with Hannas low phosphate meter.

I coveted the Hanna for years too. But do some research here and around the Net... I was shocked to find it as non-accurate as most of the test kits are. Hanna at least admits to a error range of up to .04 ppm with their low range PO4 tests...

[HighlandReefer]

Accuracy of the true reading is not as important as consistency to me, within reason. :D

I would like to be able to monitor my phosphate levels to adjust the amount of GFO I use. If the kit I use gives me a zero reading, like the Salifert Kit is for me, than it is not much good. Right now I am shooting in the dark and still have microalgae. I have no idea when to replenish the GFO or increase it, except gaging the micro algae growth (not very accurate either). Once your microalgae is under control, then this reading would be your mark on your kit to use for maintenance. :)

[Ralph ATL]

I have found DD Merck & HACH kits to be very accurate at measuring low levels of phosphates.

Todd: That independent web site from Germany is actually from Italy where Elos is made.

[Randy Holmes-Farley]

If I can't get a reading on any of my kits, then how would I know if my levels are 0.1ppms or above.

I think there may be a lot of debate on whether kits are reliable in the 0.01 to 0.06 ppm range, but in the 0.1 ppm range or above, I think all of the kits we've been discussing here as potentially accurate are going to register a reading, show a color you can see by eye, and otherwise, indicate substantial phosphate.

There are lots of things that might impact coral growth, but some careful use of GFO even if you show little to no phosphate is not necessarily a bad plan.

[lilchris]

<a href=showthread.php?s=&postid=13621980#post13621980 target=_blank>Originally posted</a> by Randy Holmes-Farley
If I can't get a reading on any of my kits, then how would I know if my levels are 0.1ppms or above.

I think there may be a lot of debate on whether kits are reliable in the 0.01 to 0.06 ppm range, but in the 0.1 ppm range or above, I think all of the kits we've been discussing here as potentially accurate are going to register a reading, show a color you can see by eye, and otherwise, indicate substantial phosphate.

There are lots of things that might impact coral growth, but some careful use of GFO even if you show little to no phosphate is not necessarily a bad plan.

I understand what you are saying sir, I know that there are a lot of things that can impact coral growth, especially SPS. I just want to start w/ getting my parameters in check. I think PO4 is the only one that I am having issues with. That is why I am trying to get an accurate reading. I know I don't have toget down to 0 but, I want to make sure that I don't have high levels either. Then I will look into my flow, lighting etc. Does it make sense? :confused:

[Randy Holmes-Farley]

Yes, that makes sense. :)

[lilchris]

Has anyone tried this test kit-- D D Merck Phosphate test kit
http://www.saltycritter.com/testkits.htm
If you have can you post your experiences

[Randy Holmes-Farley]

I've not used it, but folks that have generally believe it is a good kit and is useful for reasonably low levels. :)

[Todd March]

I think the HACH sounds interesting...

My current favorite PO4 test is how often I have to rub the Hammerhead magnet over the glass to clean it... Right now it's about once every 5-7 days, so I know PO4's are low. But I have had them low enough on my previous tank to only clean the glass once every 10 days, so I know they can go even lower...

[lilchris]

I have to clean my class about every six days. I am guessing my levels are low. It just bothers me that i have the HA.

[Randy Holmes-Farley]

Cleaning every 6 days is not much, IMO. If hair algae in the tank is an issue, maybe a yellow tang or other algae eating fish is a better option than agonizing over the chemistry. :)

[Todd March]

Do you have Turbo snails, lilchris? They are one of the only animals I have found that will eat HA. They do NOT prefer HA, and you have to keep it mowed and often hand place the Turbos onto the HA, but they will keep it mowed down very well. The Turbos combined with keeping nutrients low, have always worked for me in cycling tanks (the only time I ever have to deal with HA)...

[lilchris]

I do have turbos. I think I may add a few more. Ihave more astrea(sp) snails--the cone shape ones.

Mr. HF- I already have an Altantic Blue tang in there. He does not bother the algae, at least from what I have monitored. I have 3 wrasses, not sure I can put anymore fish in there, don't want to overstock.

[Randy Holmes-Farley]

OK. :)