Basic water purification questions by newbie

[docjohn]

I am in the market for water purification but am trying to become an informed consumer first. It seems that the best system from what I've read is an RO/DI. However I don't really like the idea of wasting our most valuable resource and correct me if I'm wrong but RO systems can waste 90-95% of the water entering the unit. Since DI systems apparently are 100% efficient, wasting no water, why not use one alone? Is it that the final product is not pure enough? Which raises the question, for a reef tank how pure does the pre-mix water have to be? How much does this requirement change for a fish only/live rock set up which is what I have at the moment (planning to start with coral as soon as I can afford the lighting!).

[Clownfish518]

DI systems use chemical resins that will need to be disposed of when used up. This creates pollution of another sort. Using RO along with DI is a greener solution.

I have an RO DI unit and my premix water is 0 TDS. A lot of people achieve that - its not too hard.

If the waste water bothers you do something with it. Some people plumb the RO/DI inline with the washing machine so when they do a load of clothes, they get pure water made and the waste water does the laundry. Nothing says it has to go down the drain - its perfectly good water.

A FOWLR tank does not need as pure water as a reef tank. If they are doing fine I would not worry too much. I use RO/DI not because I stress about purity of the water, because I really don't; but I want consistent batches of top off and water for water changes.

[chipmunkofdoom2]

If you want to talk about green and you're concerned about the environment, this isn't the hobby for you.

Everything about reef aquariums is wasteful simply due to the fact that this is a hobby and not a necessity. Throw in the fact that we try to replicate lighting intensity close to that of the sun, the materials to make the tank and all other equipment (and the waste and pollutants associated with that), the electricity to run all the equipment, the carbon to transport everything, the fact that we're stealing life from the coral reefs of the world to stock our tanks, the waste associated with spent light bulbs and other discards from hobby use, the large carbon footprint that comes with anything Chinese-made, and you have an environmental monster.

By the way, unless you're polluting water beyond purification, you can't really "waste" water. The same water that's on the planet has been here since the big bang (or since whatever god you believe in decided to make it). The dinosaurs drank the water that is here now. You can waste the resources spent purifying it by dumping it down the drain, but from the drain it usually goes to the rivers, and to the oceans then comes down as rain and gets used all over again.

[DaveK]

Originally Posted by docjohn

... correct me if I'm wrong but RO systems can waste 90-95% of the water entering the unit. ...

The figure is closer to 65% to 80% of the water from an RO/DI unit is "waste water".

However, you do not need to discard this waste water. It can still be used for just about anything normal tap water can be used for. It will simply have a higher concentration of what was in it to begin with.

[reefnut]

check this out. something to think about.
Tap Water Filter (Aquarium Pharmaceuticals)

[DaveK]

Originally Posted by reefnut

check this out. something to think about.
Tap Water Filter (Aquarium Pharmaceuticals)

I respectfully disagree. This would be a poor choice for anyone that had a tank larger has a small nano. The replacement cartridges are expensive, and do not last that long. Remember you have no RO unit up front removing about 99% of the TDS. You will quickly spend more on replacement cartridges than you would have spent on that quality RO/DI unit in the first place.

[tnwillia]

You can run your waste water out into your yard/plants/garden. Lots to do with it.