2 part demand decrease after adding more sps?

[Flatlandreefer]

So I have had my tank up and running for close to a year. I have had a mix of sps and lps in the tank with good growth from most of the corals. I have had dosing pumps running on the tank for the past 5 months and had them dialed in to maintain constant params for the past several months. I added an acro "mini colony" a monti as well as 5 acans 3 weeks or so ago and ever since the additions my alk has been slowly creeping up from a steady 9.4 dkh to 10.4 dkh prompting me to decrease the daily two part dose.

The test results are the complete opposite of what I would expect, why would my ca and alk consumption decrease with a bigger sps load and continued growth from everything else?

 

[Randy Holmes-Farley]

You might expect a small demand increase (acans grow slow and a small acro isn't adding much), but other factors may be predominating at the moment, including possible drift in the dosing pumps, changes in nutrients, temperatures, pH, testing errors, etc.

I'd just adjust the dose and not worry too much about exactly why. lol