Sooooo...unfortunately I've decided I have no other choice than to remove all the stuff in my tank to catch...a...well...yellow clown goby that has managed to take out 3 duncan colonies. Basterd!!!! Anyway, I'm pretty sure I'm gonna be taking out most of the water and yes I could just put it back in but I normally do 20% changes every week anyway so why not go a bit bigger. What's a safe amount???