Well I'm finally getting my Discus after months of trying to decide if i wanted to devote so much time to water changes. I'm using a 125 gallon established tank. I'm planning to take out the gravel and replace with sand and add 1 very large piece of driftwood and a few fake plants. Here's my question: How can i make sure the tank is clean prior to adding my Discus? I mean no parasites. I don't want to put new Discus in a tank that may or may not have parasites that will get in my Discus. Should i treat the new fish with Metro as soon as I get them? I'm also planning to do 2 50% water changes a week and see if this is suffiencent. I'm getting 5 P. Eruptions.