Salifert test kit (calcium)
 

So I bought this test kit and I have used it twice so far. The first time I used it was on Aug 8th, I got a reading of 500 but was expecting to see between 400 and 450. I figured 500 was possible if the old kit (instant ocean brand) was screwy so I didn't think to much of it. I did a 20% water change last night and now I wanted to get on track with maintaining calcium at about 450. So I tested with the salifert kit again and now it's giving me a reading of over 500. This is impossible right? I've added nothing to raise the calcium since July 30th and with the last test in my old kit I got a reading of 480 on July 31st. I thought I would see where I'm at now and then start a calcium maintaining procedure. So the big question is... am I reading the instructions wrong or is this kit faulty? What are the salifert kits generally like?

Thanks for any advice

PS the calcium "load" in my tank should be quite low, I don't have to much for LPS/SPS yet and there is a medium size clam in there.

If you are a Instant Ocean user make a batch with a salinity level of 1.026. the calcium level will be approx 360-375. I haven't been particularily impressed with the Salifert kits of late. Lots of chatter on RC about their Alkalinity test kit and false high readings.

Unfortunately I just ran out of IO a couple weeks ago, I went to pick up another bucket but they didn't have any. I needed salt so on the LFS recommendation I bought a bucket of Ocean Pure Pro instead.

Interesting. I suppose the only way to know is compare it against another test kid. I have an ELOS test kit, which have received pretty good reviews. It's $35 I think, so if you want to use my test kit to compare, I certainly wouldn't mind!

I was told that even though Salifert test kits appear to have the "resolution" to be very accurate, it isn't uncommon to do 3 tests in a row and get 3 different results.
Elos kits on the other hand don't seem to have as much "resolution" but at least the tests come out the same each time when testing the same water sample

Hmmmm. I was getting high Alk readings on my FOWLR, using Salifert, but my Reef tank was testing fine. Now I wonder if the FOWLR was/is fine, but the Reef was/is actually low!

Thanks for the offer Drew. It kinda sounds like this Salifert kit is no good. I'll try to return it to the LFS, they are usually pretty good about satisfaction. Where did you get the Elos kit?

Bought it at Gold. Pretty sure they have a wide variety of both Salifert and Elos test kits.

I have gotten away from using chemical test kits for calcium. I don't know how accurate they are. My Pinpoint calcium monitor got wet in November (stupid me). I temporarily went back to the old test kits (none were expired). I was not sure where my calcium levels were. I tried three different kits and was getting such a wide range of results.

Nov 19:
Instant Ocean 390 ppm
Aqua Pharm 500 ppm (480 ppm repeat test)
Nutrafin 560 ppm (560 ppm repeat test)

Nov 24:
Instant Ocean 390 ppm
Aqua pharm 440 ppm (500 ppm repeat test)
Nutrafin 540 ppm (540 ppm repeat test)

I compared two test kits to the Pinpoint 100 ppm calcium calibration solution and the 1000 ppm calcium calibration solution diluted 1:1 with RO/DI water which had a Ca of 0 ppm.

Standard 100 ppm ca solution:
Aqua pharm 120 ppm
Nutrafin 120 ppm

Standar 500 ppm ca solution (1000 ppm solution diluted 1:1):
Aqua pharm 500
Nutrafin 540

Unfortunately, I have never used the Salifert ca kit and therefore cannot comment on it.

After a few weeks I broke down and bought a new Pinpoint ca monitor and my gastric ulcers have healed. I would recommend you consider spending the extra money on an electonic ca monitor (or ask Santa Claus) as I have lost faith in the chemical test kits. No use having test kits you cannot rely on.

you know there are other places that you can buy test kits . Like Guardian Chemicals. BTW is there any difference in pool test kit vs the more expensive petshop kits?