Gonacor that i've used is 10,000iu. Confused where your getting the 1,000iu from. If you add 10ML of water to it, you will have 1000iu/mL. If you want to shoot 500iu's, then shoot 1/2mL. If you want to shoot 250iu's, then shoot 1/4mL. Add bac water slowly, swirl around, DO NOT SHAKE, until dissolved.