I was talking to a lfs the other day and asked if they think its essential to have an RO/DI on my tank. The lady there said that the water in this area (norcal) doesnt need to be ro/di'd because the ph levels are fairly clean. She then mentioned that they dont use it at their store and their tanks have no problems. She then mentioned that having an ro/di removes trace elements that youll just add with additives for your tank later. Can anyone confirm this? Ive seen many people praise ro/di's and it makes me wonder if its worth the trouble to do it.