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RobZilla04
08/07/2017, 02:54 PM
100 gal mixed reef. Just got around to installing my doser (took a while to fully understand dosing). Did a 20 gal water change to get some good base numbers and went from there as detailed below.

Post WC - Alk 9.4 / Cal 446
One week later - Alk 8.6 / Cal 430
Set up doser - 7 ml each Alk & Cal (Oceans Blend liquid 2 part)
2 days (2 doses) later - Alk 8.6 / Cal 316 & 334 back to back.

All results via Hanna Checker.

Im confused by the low Cal reading.

Alk goes in at 1010, Cal at 1045.

What am I missing?

Potatohead
08/07/2017, 04:32 PM
Most likely testing error, impossible it fell that much, corals would stop growing once it hits about 360 anyway. Based on theory if your alk fell 1 dkh, calcium will fall about 7.

RobZilla04
08/07/2017, 04:59 PM
I thought testing error as well that is why I checked again. I followed the same method as times before also. Gave a bit of manual Cal dose and will test again soon.

RobZilla04
08/07/2017, 05:09 PM
332

Is it posible the reagent A or B is bad?

bertoni
08/07/2017, 05:52 PM
I suspect testing problems, too. It'd take a large water change with a very low calcium mix to get the alkalinity to drop like that, assuming that the dosing is correct. In theory, you might be able to cause a precipitation event, but I'd expect the alkalinity to drop substantially, even with supplementation.

RobZilla04
08/07/2017, 06:08 PM
If there was a precipitation event doesnt that cause a cloudy white mess? Doubtful it would last hours till i got home to check though.

Ill order anpther batch of Cal test reagenta just to be sure.

Thx

bertoni
08/07/2017, 07:07 PM
Yes, I suspect that you'd notice a precipitation event unless you were away for a few days.

RobZilla04
08/08/2017, 05:56 AM
Cal 351 this morning. I cannot imagine that I've had four testing errors in a row. I even broke out the instructions and followed them exactly for this mornings test.

Tonight Ill mix a batch or two of water in a small cups (one low Cal and one high) to run two tests.

Might be time to replenish the Red Sea test kits and try a color match....

five.five-six
08/08/2017, 09:33 AM
I don't see a precipitation event happening at your levels without the tank being really cold and there being almost no magnesium in it. Sounds like a testing error.

Potatohead
08/08/2017, 09:42 AM
Cal 351 this morning. I cannot imagine that I've had four testing errors in a row. I even broke out the instructions and followed them exactly for this mornings test.

Tonight Ill mix a batch or two of water in a small cups (one low Cal and one high) to run two tests.

Might be time to replenish the Red Sea test kits and try a color match....

You can test as accurately as you want to but if your reagents are bad, they're bad.

RobZilla04
08/08/2017, 12:23 PM
You can test as accurately as you want to but if your reagents are bad, they're bad.

Thanks, I believe this is going to be the issue. Now I have to wait for the next batch to arrive (4-5 business days) :sad1:

RobZilla04
08/08/2017, 03:50 PM
IO salt mixed at 1.032 salinity and Cal tested at 416 via the Hanna.

Thats way low right?

So the testing reagents are bad....

bertoni
08/08/2017, 04:05 PM
Do you mean 1.032 SG? That's rather high. I think that calcium level is a bit low for that salinity.

RobZilla04
08/08/2017, 04:49 PM
Sorry that was a small test cup at 1.032 salinity (measured with refractometer).

My tank is 1.024 and measuring 350 Cal.

I did a test at higher salinity to see if the fault is the test kit reagent. I opened a new refill pack right around the time of this doesr install and test frequency.

bertoni
08/08/2017, 07:24 PM
It's also possible that the salt mix is bad, or that it settled badly during shipment. I've read reports of both of those problems.

RobZilla04
08/11/2017, 02:09 PM
New reagents and tested at 376 Cal today. Still confused. If you check the OP, Cal was 446 several hours after a 20 percent WC. Seven days later 430. Two days after that 316/334.

In any case Ive started supplementing Kents marine calcium so I dont have to modify the doser schedule yet. Once Cal is back between 400 and 420 Ill cut the Cal dosing pump off and recalculate loss over one week.

bertoni
08/11/2017, 09:05 PM
I'm not sure what happened, either, but I'd watch the batches of saltwater for a while.

RobZilla04
08/12/2017, 06:05 AM
I'm not sure what happened, either, but I'd watch the batches of saltwater for a while.

Thanks. I mixed some up to cure extra base rock yesterday was well. I have half a bucket of salt so I gave it a good mixing.

RobZilla04
08/15/2017, 04:18 PM
Been testing daily since the anomoly and last night after yet another low result (even after manual dosing Kents Marine Calcium nightly in addition to 7ml Oceans Blend through the doser per day) I thought to take the battery out of the unit. I took it out for 30 seconds, replaced, and put it back in the box.

Well Ill be damned if today it didnt read within 10ppm of the Red Sea test done the night before.

What I have learned in addition to this trick, my tank is eating up calcium at a rate higher than I thought.

Could this be due to the constant stability of the Alk?

bertoni
08/15/2017, 05:01 PM
Keeping the alkalinity above 7 dKH will increase calcification a bit, unless the animals are food or light limited, so I suspect you're seeing normal growth. Stable parameters might keep stony corals more happy, although coralline doesn't care all that much, in my experience.