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jeffrey_ropp
10/06/2009, 08:06 PM
I've been wondering about the accuracy of my Salifert calcium tests for a few months now. Despite dosing with 2-part solution, the readings were always low (around 340ppm). It didn't seem necessary to check after supplementing because I assumed that the test readings were accurate.

I've since picked up a Seachem test (which includes a calibration solution).
It measured my calcium at close to 500ppm. So it seems that I've been overwhelming my corals (a couple monti caps, 2 small SPS frags, and a frogspawn).

My questions are:

1) Assuming that calcium was over 500ppm (possibly 550), would my corals growth be inhibited?
2) Has anyone else found Salifert tests to be so inaccurate? Why?

Thanks in advance for your thoughts,

Stormtrooper
10/06/2009, 08:11 PM
Hi Jeff, I had the same problem with my Salifert CA test kit.

It had appeared to be working fine until the other day when I tested my tank
water and got a reading of 220(it is normally around 400).:eek1:

I then tested my other tank and got a similar reading. Luckily I had a container of NSW and when I tested this I also got a reading of around 220
so I knew it could not be right.

I have now ordered a digital CA meter.

David

Billybeau1
10/06/2009, 08:41 PM
Well, the good thing is calcium, even at 600ppm, is not going to hurt your corals. Excessive calcium rarely does.

I don't know what happened to your test kit other than maybe it got contaminated somehow. (It does happen).

I do not much care for reference solutions with hobby grade test kits. I have had a lot of problems with Seachems calcium kit in the past.

I'd get a second opinion before drawing any conclusions about what your actual tanks calcium reading is. :)

Flipper62
10/06/2009, 10:42 PM
I have never liked the SeaChem kits ( maybe its just me ) I have always liked the Salifert kits.

Calcium levels of 500 or 600 are not really bad & not going to hurt anything. One thing that you have to remember is, what corals do you have that will be using up the calcium. If you have a lot of corals that are using up the calcium & you are testing a week after dosing the tank, you may get a low reading.

What salt mix are you using ?

PrangeWay
10/07/2009, 08:33 AM
I used to use Salifert all the time, their whole range of test kits. Than after some problems I bought some other companies and realized about 1/2 the kits I owned by Salifert where "bad" and gave incorrect readings. Now I don't buy Salifert for any reasons, and keep multi-brands for each major (calc, alk, mag, nitrate, phospate). You'd be shocked how often a freakish kit by any company is out there. There was a point where I had 7 diffrent alk kits :) (5 read "correct", 1 off by 1dkh, and 1 in lalal land).

The morale of this post. Keep multiple kits (at least 2). And if they both read the same great, if they are different buy a 3rd as a tie-breaker. If that reads different, join a monastary.


PW

Billybeau1
10/07/2009, 09:30 AM
I still use my Saliferts with no problems. And I have plenty of other brands on hand to compare them to. :lol:

Every manufacture runs into problems every now and then. Unfortunately, too many reefers expect the world from hobby grade test kits. They just are not that precise. None of them. :)

arinova8
10/07/2009, 09:46 PM
definitly keep multiple kits for testing you never know go to be safe

jeffrey_ropp
10/08/2009, 01:03 AM
I just mixed up 5 gallons with OceanPure Pro salt.
At a specific gravity of 1.024, I measured Ca at 250ppm (double-checked).

My sample measured 425 as expected as did my tank water.

Now I really don't know what to trust.

Billybeau1
10/08/2009, 06:13 AM
How long did you wait from the time you mixed and the time you tested ?

bertoni
10/08/2009, 08:40 AM
I'm not sure what you mean. Which test kit gave 250 ppm for freshly-mixed salt? Which samples measured 450 ppm, and with which kit?

mark728
10/08/2009, 08:43 AM
Hi ,Just watch the Alk kits by Salifert my cuz almost lost his tank due to low alk, his kit was off by 4+ dkh ,I have tried to use Salifert for alk in the past and never had any luck with there kits,it would not surprise me if alot of reef tank problems on here are due to low alk from bad test kits ,my tank is at 9 1/2 dkh with Elos and 9 API , I have 3 different salifert alk kits the oldest kit is 13 months old and the newest one is 4 months old 1 reads over 15 dkh next kit reads 14dkh and another reads 11 all testing with 4ml of tank water.

rayjay
10/08/2009, 10:43 AM
There was a point where I had 7 diffrent alk kits :) (5 read "correct", 1 off by 1dkh, and 1 in lalal land).
How did you determine WHICH kits were correct for the alk?
For that matter, how does any hobbyist determine if ANY hobby kit is reasonably correct?

jeffrey_ropp
10/08/2009, 10:50 AM
Sorry if I confused anyone.

My freshly mixed water (with OceanPlus Pro) measured 250ppm with the Seachem test (I waited 24 hours before testing it).

My tank water measured 425ppm with the Seachem test. (340 with Salifert)
My calibration solution measured 425 with the Seachem test (340 with Salifert).

So, as best I can tell, it appears that my Salifert test is no good and my salt mix is way too low on Calcium. I've already sent a note to OceanPure.

Billybeau1
10/08/2009, 02:21 PM
From my experience, calibration fluids are pretty much useless when supplied in hobby grade kits. I would not trust them.

I have also had a lot of trouble with Seachems calcium kit in the past.

You have a lot of scenarios here. Could be the salt mix, the Seachem or the Salifert. Or it could be all three. Hard to tell from your numbers. Even if the Seachem is off, I find it puzzling that your tank reads much higher than the salt mix. Unless you supplement lots of calcium or are running a reactor.

Maybe pick up a cheap API calcium kit and see where that lands. They are reasonably accurate within 20 ppm or so either way. :)