Awaking an old thread. I have a 180G that I plan to make a reef tank, and want to have a mandarin eventually. Have a few chromis, a yellow wrasse, a blend and a CUC going, and started a chaeto fuge. Went to an online supplier, and it recommends a large-*** bag for the size of my tank. Was about to buy then then wondered, "aren't they just going to multiply without predators in my fuge"? Agree? Should I just add a "seed" amount, feed the tank and maybe them some phyto, and let them multiply on their own? Or is it worth spending the money (in this case, like another $50) to get a large pack of the things?