I feel the two most important factors that ensure success in this hobby are water and lighting. I use ro/di from a local company in my area. I have NEVER had any hair algae, diatom blooms, cyno and most of the common problems that seem to occur. I attribute this to the water I use. If I pick it up myself, it costs me $3-3.25 for 5gal (price depends on the amount of bottles you get). If I have it delivered, $4 - 4.50. In any event, it's well worth the cost. The way I see it is why buy a $1000 stereo and put $20 speakers on it!
Keith