Go With eco and wait for a few months. I had CRS in my tank and they seemed to do ok till I added my discus to the mix. then they dissapered! any way I started with 2 culls and after a couple months there were about 20 in the tank. So as long as the eco stops buffering up you will be ok. Also if you put a lot of driftwood and run co2 I will help bring down you ph as well.