Which test kit should I believe?

[birdy]

I have been using sea test and fast test lately, I started out with red sea but I didn't like them. The sea test says my calcium is at 350 and is not changing even though I have been adding Kent turbo calcium and dripping kalk. The red sea calcium pro says my calcium is at 400. My alkalinity is at 3.5, and my pH is 8.3. I am hoping the sea test is correct. Any thoughts?

 

[full of questions]

How old are the test kits.

 

[birdy]

The Red Sea was purchased about 3 months ago and the Sea test about 1 month ago. Both are fairly new and I don't see any dates on the boxes.

 

[kelly]

I just read a newsletter from a local marine aquarium society, and it stated the many of the kits will vary between manufacuters and also ones that are produced by the same companies. The test results were not very close. Each kit could vary quite a bit.

 

[birdy]

I knew they probably wouldn't be exactly the same, but how do you know what to believe 50ppm is quite a bit off.

 

[kelly]

On a calcium test here are the results.
Red Sea #1 450
Red Sea #2 350
Salifert 385
Seachem 420
From lowest to highest, in the same company, a difference of 100 ppm. I couldn't hardly believe the results, whom do you believe?

 

[full of questions]

Just a thought,take a water sample to a friend
or to your lfs,and let them check it!

 

[birdy]

Yeah I was thinking about doing that, just to have one more opinion. Thanks for the stats Kelly, I can't believe the difference in test kits. I am obsessive about my tank conditions because I want to have everything perfect before I start getting corals (my tank is only 3 months old) It is frustrating to think you don't really know if your tests are really accurate. I am going to buy a refractometer for salinity and a pinpoint pH monitor for this very reason. I HATE not know exactly what is going on in my tanks.