Aquarium: First Emergency, and Week 3

So, yes... I had my first man made emergency happen. I left the top off feed manually turned on, for quite a while. I forgot about this, and returned to the sump to find it overflowing. I acted quickly, and killed the feed, then proceeded to pump the excess water out of the sump, to the nearby drain. After all was said and done, the tank salinity dropped from 1.025 down to 1.016. My coral polyps were in shock, and had hidden from view. I was concerned, and decided to add more salt. I quickly got the salinity back up to 1.020, and then slowly added from there to get up to 1.025. That happened on Sunday, and by Monday when I took my weekly readings, all seems to have been settled.

My KH levels are up, to about 179 ppm, and my Calcium levels are hovering around 510 ppm. Phosphates, and Nitrates are both 0, and have been ever since I began testing.

Algae began growing in the main Aquarium. I assume this was likely the result of the active process of the nitrogen cycle, already beginning to function. To counter the algae bloom, I purchased a blue-tang. I have noticed that the blue-tang has been constantly busy eating the algae on one side of the tank, but not the other. I think, in a way, it feels more comfortable around the goby and shrimp, and thus doesn't stray too far from them.

I also purchased a higher power light for the Sump, to help grow the Chaeto algae that I purchased for the refugium. A Kessil H80. So far, I really enjoy it. The ATO automation aspect, is now installed with level switches to detect water height.

The Skimmer is still something I am working on fine tuning. I am also wondering if I want the mechanical filters in place in the sump, or if I should just let the poop flow into the refugium section.

The tank is already proving to be a source for relaxation. However, there are a few things I am wondering about.

This appears to be brain coral, so I am told. I am just wondering what the difference is between the very light brain coral, and the very dense brain coral? Is one healthier than the other? Is it a state of maturity? Should I clean stuff off of the coral? it will that hurt it?

I also noticed some small tentacles beside the brain coral. These appear to grab food particles, and pull them into the center. Is this another species of coral? or perhaps something else? You can barely make it out in the photo, but it is lighter colored, with brownish coloration around the tentacles. There is another similar creature which is almost fully dark brown on the other side of the tank.

There are also the tiny polyps, which can be kind of seen in this photo above. Small lighter colored creatures, with glowing green tenticles.

And in this corner, there was apparently a sponge at one time. The darker dirty ball of fur you see in the center of the shot, used to be bright yellow. It is now maybe dead? But there is some other yellow puffs nearby, and then there is the purple fluff which is forming in the background.

I am also wondering what these are? Are these perhaps evidence of worms? The clear tubes, and also the feathery type tenticles, make me think of underwater worm species.