There are a few ways to try and filter it and remove the nutrients but it is pretty difficult. It only really becomes worth it in places like large public aquariums where they need to replace thousands of gallons a day. I've never heard of a hobbiest who has done it.
thanks pat.. just kinda wonderin if it could be somethin simple, the RO water isnt expensive just thought it would be easier than havein to go to the lfs... and while im trying to cycle my tank i just wanna research all my options..
One of the reasons for doing PWC`s is replenishing trace elements. In the water you removed it is either lacking trace elements or has very little due to being used up during different fish and invert processes.I would not re use it in your tank. Maybe you can use it to pour on grass in the driveway to kill the grass.
You can view many of my fish and corals in my photo albums in my profile.