Lance, any chance that you accidently mucked up the recipie? perhaps a double batch or something?

Yes a little in the afternoon.

I don't see how I could have. Simple recipe: 2 cups of calcium chloride to 1 gallon of water. Pretty hard to screw that up, and I never, seldom, sometimes, frequently make mistakes.

I'm not sure but we have been having a lot less sun and the days are getting shorter... maybe that has caused your calcium consumption to go down.

Anything is possible I guess, but the corals are growing well so assumedly consumption shouldn't be down.

I assume you've double checked the test kit....

I don't use that method of Ca/Alk supplementation, but it is obvious that there are only two variables in play...

1) the concentration of the mix (if the supplier changed something, how would you know?)
2) the amount you add over time.

So..you can measure the volume that the pump is adding over time, so you know is unchanged.

You have no way to measure the concentration of your mix. You need to find a system that will enable you to check on the concentration of your mix. It won't tell you if this particular batch is wrong, but it will save you next time something goes off. Maybe you can dilute a sample 10:1 with RO and use your test kit to measure Ca/Alk/Mg. Maybe you can get a SpG reading?

Lance I'd just use the BRS calculator. Let your params fall to a little below ideal than calculate how much you need to raise back to ideal. If they do as advertised the mix is good. If the params jump again it's somehow more concentrated. I doubt that's the case though...seems to me if the BRS solutions were that much more concentrated they wouldn't fully disolve? Just thinking...don't actually KNOW anything.

What about an indoor air quality problem? (excess CO2)
You mentioned that you have air conditioning.
Has your PH changed at all?

Mitch

EUREKA!!! I've solved the riddle!

BRS had changed the concentration of their calcium chloride. The older formula was 2 cups per 1 gal of water. The new formula is 2.5 cups per gal. I order it in 5 gal pails which I keep in the garage. From it, I fill a 1 gal pail which I use to mix the solution. Labour day weekend I spent up the lake and my tank sitter for some inexplicable reason switched this 1 gal pail with an older, formula one gal pail I was using for the frag tank in the basement. So, therefore when I made up new solution I was using 2.5 cups of the older, more concentrated calcium chloride instead of 2 cups and was unknowingly overdosing the last two weeks. :eek:

See i knew it was someone elses fault. ;)