I have two corals that aren't looking so good. First my blue slimer has lost some color near the bottom of the main branch.


Second, my acropora valida is loosing its blue tips. I have a second smaller piece that seems to be fine.


The only thing I have been doing different is that I haven't used phosban in about a month. However, my cheato has doubled in size.
Here are my parameters as of today: alk 2.25 meq/l, nitrate ~2 ppm
Last week my calcium was 360 ppm.
My ph meter ran out of batteries, but I use top off water with kalk in it. November 2nd was the last date with a ph reading and it was 7.9. Also, my magnesium was 1500 on November 2nd.

Any ideas why this is happening?