Ok, here it goes… I have flatworms in my BioCube. Big, FAT, RED ones. I don’t know where they came from. This tank has been up for over two years, and this is my first encounter with these little buggers. All of the sudden they appeared EVERYWHERE, probably within a couple of weeks. At first I thought they were the babies of my Hawaiian Strombus Grazers (tiny snails), but after I posted a picture to my local club forum someone identified them. Apparently they are bad. I can’t say that I disagree, but they do not bother my coral. I did some research, and decided to get rid of them.
As some of you know, I am a big fan of the “natural” or at least “non-chemical” approach. So the first thing I did was look into the alternative to the Flatworm Exit. Apparently there are a bunch of different crabs, shrimp and fish that will eat the flatworms or their offspring. Unfortunately, that will only happen if there is no other food supply, and most of the time they will find something better to munch on. Anyway… I was not in a hurry, so I decided to get some expert opinion. While at a local fish store, the owner shared his own experience with the flatworms. He said that you can’t completely rid your tank of them, you can keep them under control though. He also stated that any popular chemical treatment will only help build the immunity of the flatworms, especially if you do several treatments. He also prefers the “Natural” approach, so he suggested I get a carnivorous fish. $12 later, I have a beautiful Scooter Blenny !! I named him Ashton. You know… Ashton Scooter. 
After only 4 days in my cube, I noticed a drastic change in my flatworm population. They were changing color, from brownish red to ash grey. All my rock and even coral were covered in what looked like ASH. I did a thorough cleaning, took every piece of coral out, and rinsed it under a faucet (flatworms hate freshwater, and wash off in thousands). After placing all the “washed” coral into a bucket with some fresh saltwater, I repeated the “wash” with all the rocks in the tank. After the wash, I siphoned as many of the flatworms out of my Cube as possible. I ended up taking out about half of the water, which was replaced with fresh made saltwater. It looks much better, there are still a couple of worms that I noticed, but just a couple. We will see how it goes. I will keep you posted.