Accuracy of Red Sea phosphate test kit?

[ampemployee1]

I use the Red Sea Phosphate test kit. I have measurements of 0.08, which is high considering I keep a couple of varieties of birdsnests. I don't have any algae other than my chaeto in my fuge and some red macroalgae in the main display.

I see really good coral polyp extension and growth, and cut about 2 softball size pieces of chaeto from the fuge monthly, so I wonder how accurate the test kit is. When I first got my pink birdsnest, it was mostly tan, and is now mostly pink, except at the base, where its still tan. Sorry for the poor picture quality from my iPhone. I can't figure out how to take good pictures under LED lighting.



I do feed the fish (6 anthias) around 4-6 times per day, so I wouldn't be surprised at a high phosphate reading.

I wonder if anyone knows how accurate the Red Sea test kit results are. Thanks in advance for the feedback.

[Yogre]

I have the Red Sea PO4 kit, too.

There were, or maybe still are, problems with this kit. The dropper bottle that dispenses one of the reagents (I forget which) is inaccurate, resulting in a PO4 reading which is never less than 0.08.

There is a workaround which involves pulling the cap off the reagent bottle and dispensing with a syringe. This workaround may be detailed in the Red Sea sponsor forum, if I can find it today, I'll post back here.

Long story short, you may have an inaccurate kit, and your PO4 may not be as high as 0.08.

[ScottB]

I have that kit as well, and I have .08 PO4 as well, and I have no algae as well. This has been driving me nuts. I am running Bio-Pellets and GFO to get PO4 down, and now I find out I might not have any to begin with. Man, this is a bummer.

Thanks for bringing this up. I think I need to find a new kit, or at least the work-around.

[ScottB]

I just found the thread: http://www.reefcentral.com/forums/sh...eferrerid=1642. Basically you use .5ml of reagent A, instead of the dropper.

I went back and followed the work-around and tested 0. Now I wonder if the GFO was enough without the BP reactor? I guess I will start scaling back the GFO and see.

[ampemployee1]

Thanks for the feedback. I'm going to take a water sample to my LFS to correlate my phosphate readings, and also try the work around you listed above for the test kit.

Cheers, Ed

[Yogre]

Originally Posted by ScottB

I just found the thread: http://www.reefcentral.com/forums/sh...eferrerid=1642. Basically you use .5ml of reagent A, instead of the dropper.

I went back and followed the work-around and tested 0. Now I wonder if the GFO was enough without the BP reactor? I guess I will start scaling back the GFO and see.

Excellent, thanks for finding this. I'm going to try the work-around as well. I have very little algae, even on my glass (I dose vinegar), so I'll bet my PO4 is low as well.

Lower than 0.08 at any rate.

[Buzz1329]

I could not coax a meaningful reading out of the Red Sea phosphate test kit.

[Reef1121]

It is possible that you do in fact have phosphate in the tank. Saying that you have significant growth in your macro algae eludes to that fact (and maybe low to mid trates) off the bat in my mind. I use the same test and it was around .08 for the longest time until I started using their NoPox supplement. Once my nitrates started dropping below 1ppm the phosphate started dropping farther as well. I tested today and have .35 nitrate and .06 phosphate. (test color was in between shades on both) Just my .02

[bertoni]

I would double-check the kit before doing anything, given that the corals are doing well. That's true for any brand of test kit. I trust the corals more than the test kit.

[Englishmatt]

Yup...I use the same kit and the NOPOX dose and get a .02 reading. I had
.08 for about 4 weeks but the last 2 tests have been down to .02

Just my .2c

[tmz]

I think seriatopora will do ok at 0.08ppm PO4 based on my experience with the m.. They are more sensitive to high NO3.
Any hobby test kit and most colorimeters are going to have a =/-.04ppm accuracy rating in any case.
I do not have any experience with the Red Sea PO4 kit.

[ampemployee1]

Originally Posted by tmz

I think seriatopora will do ok at 0.08ppm PO4 based on my experience with the m.. They are more sensitive to high NO3.
Any hobby test kit and most colorimeters are going to have a =/-.04ppm accuracy rating in any case.
I do not have any experience with the Red Sea PO4 kit.

Thanks. This feedback was actually what I was looking for when I originally posted. I use the Red Sea Nitrate test kit, it measures 0ppm. I feel the chaeto, skimmer and weekly water changes are keeping this parameter in check. I'm guessing my phosphate are probably somewhere within the range of 0.03 to 0.06. No cyano, and the birdsnest polyps are fully extended, so I'm not going to mess with introducing a reactor at this time.

Appreciate everyone's inputs. Ed

[kissman]

I got the algae control kit and my PO4 was reading between .04 and .08 was still hard to tell color but was better than the salifert which always read 0 once I got it down. Since I was having trouble reading the colors still I bought a Hanna 736 and it reads .04.

[ampemployee1]

Arvind from Red Sea contacted me and suggested I try testing my make up water using the syringe to measure 0.5ml of reagent A. Good news, my make up water measured 0ppm. I dropped about 15 drops of reagent A into a small container and sucked it up with the syringe. After shaking out the air bubbles and moving the plunger to 0.5ml, I expelled what looked like about 1 drop of the reagent. So for future testing, I'm going to use 14 drops of reagent instead of the 10 per the instructions.

I tested my system water using the same protocal, it measured 0.02 ppm. I am happy that my make up water isn't introducing any phosphates and that my system levels are being kept in check through the maintenance and measures I've put in place.

I have to wonder if the removal of the Chemipure which was 4 months old helped, and was potentially leeching phosphate back into the tank. Anyway, glad I got the testing issue resolved, and do not have to do any additional research into phosphate reduction approaches.