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how do you know when its time for an ro/di unit


maxwell

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I have had a biocube 29 for close to two years now. I've always bought fresh ro/di water for topping off from the lfs. Now I have a 57 gallon with a sump and all the goods that goes with it. Between the two I am using anywhere between 5 to 7 gallons of freshwater a week top off. So I went on bulk reef supply and started looking into ro units. What I read astonished me. Their units have anywhere from a 3 to 1 to a 5 to 1 waste to product water ratio. At 3 to 1 that means that for every 50 gallons of pure water you make, you get 150 gallons of waste water. I have a well and the thought of discarding that kind of water...well, frankly it worries me a bit. I never realized those things were that inefficient. So my question to you guys is where do you draw the line that its no longer worth paying fifty cents a gallon to the lfs for fresh water to spend the money for a unit and then to have to dump that kind of waste water when you use it. I'm just trying to figure out what's the best thing to do. Thanks for your input.

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Do you pay by the gallon on your well? Is it a money concern?

 

If the concern is simply the wasting water part.....then you are screwed either way since the LFS is wasting just as much water as you would ;) Why not at least waste the water but save some money by making/wasting it yourself.

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I have had a biocube 29 for close to two years now. I've always bought fresh ro/di water for topping off from the lfs. Now I have a 57 gallon with a sump and all the goods that goes with it. Between the two I am using anywhere between 5 to 7 gallons of freshwater a week top off. So I went on bulk reef supply and started looking into ro units. What I read astonished me. Their units have anywhere from a 3 to 1 to a 5 to 1 waste to product water ratio. At 3 to 1 that means that for every 50 gallons of pure water you make, you get 150 gallons of waste water. I have a well and the thought of discarding that kind of water...well, frankly it worries me a bit. I never realized those things were that inefficient. So my question to you guys is where do you draw the line that its no longer worth paying fifty cents a gallon to the lfs for fresh water to spend the money for a unit and then to have to dump that kind of waste water when you use it. I'm just trying to figure out what's the best thing to do. Thanks for your input.

 

Its not that theyre inefficient, its that theyre too efficient. You want that kind of wastewater production with an RO/DI so no contaminants are in your freshwater supply. As far as the wastewater goes save/store it and use it to water your car, lawn, house, driveway, wife, dog, kids, etc ...

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Anything under 4:1 isnt going to be as efficient. 4:1 is the industry standard. Typically lower does not flush the membrane as it needs to and will eat up Resin like crazy especially if you have high TDS.

 

Also remember that on a well system the waiste water will go back into the water colum on your property.

 

Its not like it is a huge waiste factor.

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Ok...so let me put it this way I guess. For people who are on a well, is it safe to produce that kind of water to only use 1/3 to 1/5 of it and dump the rest. I have a new house with a new well but 10 years down the road I wouldn't want to be running the well dry because of all the water I've wasted through the years. Up till now I've always been on city water water so I have no experience with a well and how they work or how much water they produce over a lifetime. As far as what the lfs waste's to make it...I don't really care, they are the ones paying the water bill. Thanks

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Run the waste to a landscaped area and you are doing groundwater recharge helping the aquifer.

 

I opted for the Spectrapure MaxCap UHE which wastes less than 1:1 but its not a cheap proposition. If you can justify the initial cost it will pay for itself over time though.

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if your running you well dry in 10 years you're using ALOT of water. most wells are dug pretty deep so that doesn't happen. i've got a ranch with a well down at 300 ft and i use it to keep the lake full during droughts in texas. so odd are you are not going to run your well dry. (the lake is on the smaller side 4 acres X 30 ft deep when low, filled to the max is about 50 feet and about 6-7 acres.)you can figured the water content there. so like i said your well should be fine.

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The well is DEEP.. you are not goin to destroy nature. If you using even 10,000 gallons in 5 years.. you will not be able to deplete the waer table, it comes from miles away. The only time you need really worry a bout it is if there is a 'drout' if you run your well too dry its going to get ugly. It starts smelling like sulfer before this happens.

 

You know your washing machine can use 35-50 gallons per run?

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I run my RO/DI into a 32 gallon Brute trash can in the backyard. The waste water goes into the pool to top it off or I'll have it run into my other trash can and I use it to water the plants. That way the water isn't going to waste because I'm on a water meter.

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jeff@zina.com

Waste water options:

 

1) Water the lawn/garden

2) Fill the washing machine

3) Fill toilets

4) Use for showers

5) Use for a pond

6) Top off a swimming pool or spa

7) Drink it

8) Wash the cars

9) Water the animals

10) Down the drain

 

There are lots of options, some requiring more work or plumbing, but you can always use water.

 

Jeff

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You could but its not wise. It will be 20-25% higher in TDS than the tap water was to begin with which is what you are trying to remove or reduce.

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