Not sure if its just me, but I dont see the "green bubble" in any of the pics. Either way, it's probably either green bubble algae, which looks like a shiny green marble, or just green coraline algae. Coraline is good. If it's green bubble then you want to get rid of it. you can just carefully pull it off the rock and throw it away. Don't break the bubble though. If it breaks, it releases spores that will all lead to new bubbles. Emerald crabs will eat green bubble algae should it become too big of a problem for you to manage on your own. As far as the other color changes its just the normal coraline algae starting to grow. The white coating is die off on the rocks. That is what is causing the ammonia spike. It's normal. Last thought: You need to get a test kit. The yellow dot is not an effective way to get an accurate reading, and your water parameters are too important to short cut this. Go get a marine test kit that will allow you to check for ammonia, nitrites, and nitrates as a minimum. KH, Calcium, Phosphates, and Magnesium are all good to be able to test for later, after you start stocking. API, Kent, and Seachem all make decent kits. Good Luck