No coral obtains 100% of it's Daily Carbon Budget from photosynthesis contrary to what people have read on the internet. Some corals absorb DOM (Dissolved Organic Materials), some eat zooplankton, there are a FEW that eat phytoplankton, some eat bacterioplankton, some capture POM (Particulate Organic Matter). Some do a combination of several of the above. For example: Many Acroporids eat zooplankton, DOM, POM, and not only do they eat bacterioplankton, they actually "farm" these bacteria. Reef Food by Eric Borneman - Reefkeeping.com From the Food of Reefs to the Food of Corals by Eric Borneman - Reefkeeping.com The Food of Reefs, Part 3: Phytoplankton by Eric Borneman - Reefkeeping.com The Food of Reefs, Part 4: Zooplankton by Eric Borneman - Reefkeeping.com The Food of Reefs, Part 5: Bacteria by Eric Borneman - Reefkeeping.com The Food of Reefs, Part 6: Particulate Organic Matter by Eric Borneman - Reefkeeping.com The Food of Reefs, Part Seven: Dissolved Nutrients by Eric Borneman - Reefkeeping.com A good GENERAL rule would be to look at the size of the "mouth" and how much tissue that mouth has to support. Take a Euphyllia (Frogspawn) for instance. Each polyp has a mouth that is fairly large and each polyp also has a whole lot of tissue to support. Well, that means that periodic target feeding of mysis shrimp would be good to give that coral. Contrast that with a Lobophyllia brain coral. Depending on the size of the coral, mysis might be a good choice or maybe even small krill. Now consider a Cladiella (colt) coral. There's all sorts of tissue to support but there are hundreds and hundred of small mouths to support it. Cladiella could benefit from a particulate type of coral food but it certainly can't eat brine or mysis shrimp. Now look at your average SPS coral, many tiny mouths supporting tissue that is only 2 cells deep. If you go squirt mysis or brine on them, it's just going to bounce off and make your fish happy.