[scubadude]

Its always been preached that RO and DI water is the best to use for an reef tank. But after reading some recent info im starting to wander about the waste water we are throwing away with RO units and the effeciency of just DI water. Come on all you DI-only users come out of the closet and tell us if you think that DI-only is the way to go, even though you have used RO units before.

[Reefland]

Rocky,

I once used the "tap water purifier" which is nothing more than DI resin. The water filtered by the unit was decent, < 10 TDS however the resin was exhausted so quickly. I think the benefit of RO before DI to help remove impurities before the resin which helps extend the life of the resin in addition to the additional cleaning that is performed, is well worth it.

[FesteringGob]

Can I ask a stupid question? What does RO and DI stand for? No laughing please.

[Poseidon]

RO stands for Reverse Osmosis, and DI stands for De-Ionization... No laughing required!!!

[kevinpo]

RO then DI is really required for my area for long-term reefkeeping. The total TDS (total dissolved solids) reads between 86 and 145 ppm depending on the time of year. We have what is considered some of the best drinking water in the nation. It comes from one of the largest aquifers in the world (42 miles long). My water company doesn't even chlorinate it. It has phosphates (.3), some silicates, 5ppm nitrates, and in some locations high iron content.

If you fill your tank with this water it's really no problem. You get a little diatom bloom on the front glass the second day and that's about it. The problem occurs after 12-18 months (depending on your evaporation rate. I add 12 gallons a day) of replacing evaporated water with tap water. The rocks and sand absorb the phosphates from the food and water you add until they cannot hold any more. Then macro algae begins to really bloom . In a smaller tank you cannot put enough herbivores in to keep up with it.

I run 3-5ppm out of the RO membrane and 0ppm out of the DI. You can still get algae blooms from overfeeding but that is much easier to control (sort of. They're such beggars ). Remember the water that goes as waste is still drinkable, just high in minerals. It can be used to water your lawn or recycled by the sewage treatment facility. There is about the same amount of water on earth that there was in the beginning . The only thing that is being wasted is the energy to provide the extra water to your house. If you compare that to the energy the farmers use to flood the desert in California to grow rice it's a drop in the bucket so to speak .

Regards,
Kevin