If your adding eco complete to an existing tank it needs to be rinsed very well. I recently did this. I was changing out some substrate. I did it slowly over 1 1/2 months. I will caution you, it raises ph. It claims it doesn't, it did to mine. When I asked about it at my LFS they confirmed it. I wish I would have found out earlier.
Anyway, i just rinsed with tap, since it was going into a cycled tank. Good luck. ?