Hey guys, I've been having an issue for a while measuring my calcium and not sure if it's me or maybe the test is slightly off somehow but could use some advice. I'll get to that part in a sec but first you should hear about this week...One of my tanks is a 10 gallon nano with only coral and inverts and over the past week I forgot to switch back on my ATO after cleaning and didn't notice that the tank water was evaporating a good bit which of course raised the salinity and stressed some of my corals. Today I realized something was wrong and tried to slowly add water to lower the salinity over a few hours. After getting the salinity right and also doing a water change I decided to test both alk and calcium because although I usually change water weekly it had been two weeks this time. This is where I'm confused. I tested alk before the water change and it was 7.6 which isn't far from my target of 8 I keep the tank at... calcium I also tested and it came in around 350 with a Red Sea kit. I also tested the freshly mixed saltwater I made and calcium tested at 400 (should be around 420, so maybe the kit that's always seemed to test low really does test slightly low) and alk was almost spot on at about 8.2 (should be 8).
Here's my question finally. The tank calcium usually tests around 375-380 so it would have had to drop 25ppm over two weeks with not a whole lot of coral and alk would have only dropped by around .4-.6 dKh. Does this sound proportional or do I likely have some testing error somewhere?
I should note that a couple corals which look very happy such as a cyphastrea I've had for a few weeks haven't grown much if any so perhaps there is a calcium deficiency?
Sorry for the lengthy post.
Here's my question finally. The tank calcium usually tests around 375-380 so it would have had to drop 25ppm over two weeks with not a whole lot of coral and alk would have only dropped by around .4-.6 dKh. Does this sound proportional or do I likely have some testing error somewhere?
I should note that a couple corals which look very happy such as a cyphastrea I've had for a few weeks haven't grown much if any so perhaps there is a calcium deficiency?
Sorry for the lengthy post.