Wierd Calcium Behavior

[jtroutt19]

Hey guys I was at work today and had a gentleman come in to get his calcium tested. It ready around 250ppm. A week ago about it was at 380ppm. He does not have a high coral load and has not done a water change since about 2 weeks ago. He has had the tank set up for 5 years and never once had this problem. Any ideas on what can cause a calcium swing like this all the sudden? He does not dose the tank with Mg or test for it. So not sure on that level. Thanks for any ideas!

[bertoni]

How much alkalinity supplement went into the system over that time frame, and what was the change in alkalinity? Some of my tanks would go through close to 20 ppm per day with good conditions.

[jtroutt19]

Not sure about the answer to that question, He doses with a 2 part calcium additive I will try and get the name of it today. I could understand a small swing but a swing of 120 ppm makes me think something else is going on.

[Percula9]

Probably precipitation is the problem or a testing error occured.

[bertoni]

We need to know what was dosed into the systems to say much. I'd especially include pH buffers and alkalinity supplements.