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Discussion Starter #1
What would be the best way to test out the accuracy of my Red Sea Phosphate test kit? I've been dosing .3g of PO4 (1.1ppm) to my 50g every other day (along with 1/2TSP NO3 every other day) and haven't been seeing the phosphate register on the test kit. I get about a 0.1ppm reading from the test kit. Granted, I don't perform the test after I dose the phosphate. Rather, I test the phosphate level the morning prior to my dose -- which means my previous dose from 2 days ago may have already been sucked up. ;) The nitrate seems to be registering on my Lamotte kit just fine.

I'll try to test right after I dose. I'm relying more on the Estimative Index for dosing, so the test kit isn't crucial, but I'm curious to see where my levels are following.

I've heard something about doing a bucket test? I have a 5 gallon bucket sitting around.

I heard Red Sea was one of the better test kist for Phosphates.

thanks!
steve
 

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motifone:

You have the right idea-Bucket Test.

Since you already have the bucket, the test kit, and a way of calculating/weighing required solid I give you three gold stars and will assume that all you are waiting for is for somebody to confirm the bucket method.

If I am wrong and you question does not need the above response you still get one gold star for not dumping solids into the tank until the test does read high.
 

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Bucket test involves dosing a known ppm level in a given amount water.

According to Chuck's dosing calculator, if you mix .25 tsp of KH2PO4 with 200ml of water, adding 1ml of this solution to 1 gallon of water should give you 1ppm of PO4.

Use distilled or RO water for the solution and test water to ensure that you don't affect the outcome with any PO4 that may be in your tap water.
 

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who told you RedSea was a good phosphate test kit? SeaChem is the only phosphate kit I trust. Too many people report all sorts of problems with the entire RedSea line of test kits...especially their Nitrate kit.
 

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Discussion Starter #7
malkore,

I had read several forum threads before buying the phosphate kit. Red Sea came out the winner with the most high marks. That's not to say Red Sea is "the Best kit" or Seachem didn't have any supporters, but Rea Sea did come out ahead in my casual poll.

Now, that said, I will do a bucket test tonight. If anyone else wants to chime in on their preferred phosphate kit, feel free to do so.
 

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I tried both Hagen and API before settling on the RedSea PO4 test. The other two were just too hard for me to get a color match with. Never tried any of the SeaChem tests so can't comment one way or another on those.
 

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I've used pretty much all the Red Sea kits and they are top notch IMO. Only NO3 and Fe (like every other brand) didn't work. Many, many reports have come out about problems with the NO3 kit, but I seriously have NOT read problems on the entire Red Sea line.

The Red Sea PO4 has been the worked flawlessly for me.

Lately I've realized some aren't reading the directions carefully for the PO4. To compare the color against the color chart, you must look straight down the test tube. Not by the side. This makes all the difference.
 

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Discussion Starter #10
Well, looks like I jumped the gun...

Did a bucket test tonight on a bucket of tap water. Tested the water before adding phosphate and tested again after adding phosphate. I got a solid 1ppm reading on the Red Sea test kit for the water with 1ppm of phosphate added.

More than likely, my tank is chewing through the 1ppm phosphates faster than I thought -- hence, the low phosphate reading after a day of dosing. ;)
 

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Aftica said:
What range does the Seachem phosphate kit do? I thought it's lower limit was 0.5 ppm?
Seachem does it for me. This is a quote from their website about their Phosphate test kit.

This kit measures inorganic phosphate down to 0.05 mg/L, producing a unique easy to read yellow-green-blue color range in marine and freshwater.
 

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yes - (my typo) it is actually as low as 0.05 mg/L..

My biggest problem with Seachem test kits is reading the results - that sliding scale that they use I find not very easy to read at all. I have a Nitrate kit from Seachem that just sits in the fish supplies closet for the same reason. I only break it out on rare occasions just to use the Nitrite portion of the test...

I bought the Seachem kit to replace the Hagen Nitrate kit that I was not pleased with. After both these I got very frustrated and bought the Lamotte and I am throughly satisfied with it.

My biggest problem in where I live is actually getting the Red Sea PO4 - The last time I ordered it my mail order supplier said he was dropping it from his inventory - slow mover... I begged for him not to (he is a smaller operation so you get to know the people) and told him it was a great kit for planted tank people - seems he listened as he is still carrying it - for now.
 

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I did a bucket test for my Red Sea PO4 test yesterday after all three of my tanks registered about 1.5ppm. Added 1ppm of KH2PO4 to 2gal of RO water and it came back with a well matched 1.0 against the reference chart.

I've also tried an API PO4 test (yellow-green-blue) that I could never get a shade that was anywhere near those on the reference chart.

For now I use API for Nitrate, GH, KH, Ammonia and Nitrite; RedSea for PO4; and Salifert for Ca.
 

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The other thing about the Seachem test kits is that most of them (including their phosphate test kit) include a "reference" solution so that you can use it to test the test kit! :proud:
 
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