how much kalk paste before crash?

[cjames]

Ive had a severe problem with colonial hydroids for years specific to one rock. It doesnt hurt the hairy mushrooms on it and they are massive (2 just split this month and all are over 4 inches across minimum). Ive never had a problem with them because I have always had ample space between it and other coral. Now I need to take action. If I am to kill them with kalk paste, I would need about 10 basters full (lol we arent talking syringes here) -- Its bad. So my question is how much kalk paste is normally ok to add to a tank at once (12 gallon: ~8ga water). Im going to town on pests this week. First hydroids, then my flatworm problem when exit gets here in the mail.