[Myka]

Agreed. Do check the TDS before buying a system though. If the TDS is really high then you need more stages, if the TDS is really low you need less stages. FWIW, I have a 150 gpd system for my 90. It was 75 gpd, but I upgraded it, and it is much nicer to produce water faster. Bulk Reef sells 150 gpd membranes for only $65. BRS is really the place to go for RO/DI imo. Their shipping is very reasonable too, no hidden fees (they pay brokerage for UPS). They have "free shipping" on orders over $175 which is only good for the US, but up here in Canada we would get discounted shipping too. BRS is the only supply place that I order from with any regularity. Also a good place for GFO and carbon.