How Fast Can an Acro Uptake Elements?

[kalmanb0y]

I am new to the reefing hobby, and I just set up my first Mr. Aqua 12g Long aquarium. After the cycle was finished, I threw in a few test zoas, and they did fine, so when I saw a large frag of an acro labeled "garf bonsai" at an LFS for a good price, I couldn't resist buying it. I didn't have great expectations for the health of the coral, but I had heard that validas were more hardy than some other species of acros. A few days later, the coral is looking great in my tank, but my parameters are acting weirdly. I am using Tropic Marin Pro Reef salt, which has a base dKH of around 7.0, which I boost to 9.0 using Tropic Marin All-for-Reef. I had tested alk a few times, and it had always been within +- 0.2 of 9.0, which wasn't a surprise, since I only had the zoas. The morning after I added the acro, the dKH was 9.0. The next day, I tested and it was down to 8.6 according to my Hanna Alkalinity Colorimeter, so I dosed, according to the All-for-Reef jug, 2ml. The next morning I came back and tested and the alk was 6.6. I thought something was wrong with the colorimeter, so I tested some freshly mixed 35 ppt saltwater and it tested 6.9, which is accurate. I dosed 4ml of All-for-Reef and tested the next morning and the dKH was 6.9, and there were some very small brown dots on the glass. I haven't seen any white precipitation. Are the small brown dots some weird form of precipitation? Is this some microorganism that is uptaking alk? Can a single large frag uptake this much alk and the little things on the glass are unrelated? Any help is appreciated. Below are some pics of the colony. I cannot for the life of me get a picture of the brown dots, they are only visible within around a foot or two of the glass.

 

[kalmanb0y]

Also I have heard that it can take up to a day for All-for-Reef to affect chemistry, and there is no difference between before and after I dose the All-for-Reef. Is this true? How many hours after I dose will alk peak?