So rather then getting a zapper I thought I would try using aptashia x from red sea who I have always like there products. came with a syringe that had two different types of needles that could be screwed on for reaching hard to reach aptashia. I had a few thats disk where larger then a silver dollar and stood several inches tall. I followed the instruction and the stuff worked great. I was surprised how well it worked which is why I am posting this thread. This product gets a A+ from me. Only thing it didn't have in the instructions that I did differently is I did it only a few hours before I was ready to perform my water change. If something went wrong I could have done the water change right away so my recommendation would be to use it before a water change so you have water ready to go in case of an emergency.