Calcium Issue

[Snufflupagus]

Hello fellow reefers,

I have a calcium issue happening in my tank right now, and have no clue what's causing it or how to fix it. My calcium keeps going up even though I stopped dosing it. I have a heavy stalked SPS tank. The corals are starting to bleach a little slowly everyday. I've done water changes twice now, I've changed over 40% of the water (150 gallon, 180 TWV) and the calcium is still reading between 550 and 600 on my Hanna checker. The test kits were just bought and have not expired. My Mag is 1350 and my Alk is 8.4. One day I'll do my test and the calcium will be at 520 so I think it's lowering and then the next day I test and it's up around 580 without having dosed or adding anything to the tank. I use Reef Crystals for my water changes.
Anyone have any ideas on what may be causing these levels or any tips and tricks on getting these levels lowered?

Thanks

[Coral Hoarder]

Possible you have a Hanna kit malfunction test a
times with salafert and see where your at

[westreefmang]

Yeah i hate the calcium hanna testers there garbage try the red sea calcuim kit i always double check hannas... alk. Works mint but always random readings on calcium

[Snufflupagus]

Ok thanks guys I'll try and repost my findings.

[Myka]

I don't like the Hanna checker for calcium either. I think the trouble is with the very tiny amount of sample water (0.1 mL). Measuring such a tiny amountis difficult - even with a 1 mL syringe. If you're off by 0.01 mL that's 10% which accounts for 40-44 ppm +/-. So if your calcium is 440 you could easily get a reading anywhere from 400-480 ppm. I don't like that. I don't doubt the test kit is accurate, I think there is a high rate of user error.

[reefwars]

If day 1 is 520 and day two is 580 and your not dosing anything or doing a water change then thats a big red flag that there's a testing error .....because that's physically impossible without manually adding the calcium

Testing your calcium daily is also not really all that possible or at least accurately anyways unless your dropping 2 to 3 alkalinity dKH perday which heavily stocked tanks can do but without the alk drop calcium won't be dropping that much in a day without a noticeable drop in alk and the average kits margin or error is to high for daily calcium adjustments (that's where the saying dose on alkalinity number not calcium numbers comes from )

[Snufflupagus]

Great advise guys. Thanks. Very true I should have know it was the test (or could be the test, I'm getting a new tester tomorrow) I sure hope that's what the issue is. I'll get a better judgement after testing tomorrow. Thanks for the advise so far.

[duncangweller]

I copied this from a randy holmes-farley article for you. Hope it helps:

So the first "deviation" from the rule of calcium and alkalinity balance really isn't a deviation at all.*If an aquarist is supplying a balanced additive to his aquarium, and calcium seems stable but alkalinity is declining, it may very well be that what is needed is more of the balanced additive, not just alkalinity. This scenario should be assumed as the most likely explanation for most aquarists who should look for more esoteric explanations for alkalinity decline only if calcium RISES substantially while alkalinity falls. Likewise, if alkalinity is rising and calcium seems stable when using a balanced calcium and alkalinity additive system, the most likely explanation is that too much of the additive system is being used.

[duncangweller]

There is also an article on correcting an imbalance by the same bloke

[Snufflupagus]

Thank you Duncan I'll look up those articles.