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Virtuoso
12/18/2010, 11:33 AM
Sorry if this is the wrong forum for this, but it was the most accurate I could think of. I am new to the hobby and am still trying to understand exactly what goes on in an RO/DI filter. My quick question was, could I use the "waste" water from an RO/DI unit to grow hydroponic plants? Vegetables, flowers, etc? I am trying to think of ways not to waste the "waste" RODI water and I think this would be a good use in my setup if possible. I realize I may have to add extra nutrients or whatever, but would the RO/DI waste be completely unusable for this? Thank you.

HighlandReefer
12/18/2010, 11:50 AM
It would depend on the levels of the elements in your tap water which would be increased in concentrations in the waste water. For example, if copper levels are high in your tap water then the copper level would be even higher in the waste water from your rodi unit.

If your tap water has chlorine or chloramine in it, the ammonia level of your rodi water waste water will be much higher as well. ;)

Virtuoso
12/18/2010, 12:02 PM
Thank you for the quick response. While I do not currently have any testing supplies, you got me curious so I did look up the latest water testing results from my city. Would anyone let me know what they think? While I kind of understand what these numbers are saying, I do not have a lot to compare to. Thank you!


Gross alpha (pCi/L) - 0.249
Radium -226 and radium-228(pCi/L) - 0.763
Fluoride (ppm) - 0.82
Sodium (ppm) - 17.0
Nitrate (as Nitrogen) (ppm) - 0.084
Barium (ppm) - 0.003
*Copper (tap water) (ppm) - 0.0506
*Lead (tap water) (ppb) - 4.3
Total Trihalomethanes (ppb) - 52.2
Total Haloacetic Acids (ppb) - 32.9
Total Chlorine as Chloramine (ppm) - 3.17

HighlandReefer
12/18/2010, 12:11 PM
Your tap water contains both chloramine and relatively high levels of copper (50 ppb). If you have copper pipes in your home or they use them in the pipes to your house, the copper level will be even higher.

Both Copper and ammonia (which is what chloramine brakes down to) are toxic at high enough levels to plants grown in hydroponic conditions. Given your water report and the fact that the levels of both will be increased in your rodi waste water, I would not use the waste water for your hydroponics. ;)

Virtuoso
12/18/2010, 12:13 PM
Okay, thank you for the quick quick responses. Guess I will go back to the drawing board. Really appreciate it!

HighlandReefer
12/18/2010, 12:22 PM
Your welcome. ;)

UVvis
12/18/2010, 12:39 PM
While the RO waste water would be a bad choice, as by design, it is basically the concentrated unwanted aspect of mineralized municipal water, you might have interest in these types of systems:

NASA Aquaponics (http://www.nasa.gov/audience/foreducators/9-12/features/aquaponics.html)

Aquaponics is a cool food production concept. Growing protein and plants in a mutually beneficial way... awesome.

bertoni
12/18/2010, 02:52 PM
I don't know how pure water needs to be for hydroponics, but the water should be fine for watering plants outside. If you have a 3:1 waste ratio, the parameters in the water report will be bumped up by about a third, which isn't all that much. You could compute the levels and ask an expert on hydroponics.

Virtuoso
12/18/2010, 03:42 PM
I don't know how pure water needs to be for hydroponics, but the water should be fine for watering plants outside. If you have a 3:1 waste ratio, the parameters in the water report will be bumped up by about a third, which isn't all that much. You could compute the levels and ask an expert on hydroponics.

I was actually thinking the same thing. I am doing a bit more research in growing stuff hydroponically and I am not entirely sure the copper and ammonia from the waste water would be completely unacceptable. I appreciate the advice that HighlandReefer has given me, but I may do a bit more research and do something on a small scale to test it.

Basically, I have a small patio behind my house and no yard. There is some communal grass behind my house but I think the amount of waste water I would be producing (90g tank + 40g sump) may make it a continual marsh if I were to direct it that way.

I was thinking I could set up a large barrel or bucket and pump the water from there to the plants, having it recycle back into the barrel. Do some orchids or something along the wall and a couple of rows of vegetables / herbs.

Don't even have my tank setup, or an RODI filter yet, but when I do I think I will go ahead and try a very small scale experiment. I'll be sure to post here with my results if and when I do.

izmullives
12/19/2010, 06:22 AM
rodi waste water is also great for washing clothing just collect your waste water and pre fill your washer machine

marke
12/19/2010, 07:05 AM
Forget the washer! Can you fill your toilet with it? Joking!!(still a good use of waste) I have an ro/di outside fro filling my exchange water tank. The discharge pours into my hedges and grass. Big puddle when your doing 100 gal. I see no difference in that section of bushes than the ones that dont get ro. Hence maybe try it on a sample, one with one without.

rayjay
12/19/2010, 07:15 AM
If you are growing hydroponic vegetables INDOORS, be prepared for a whopping hydro bill.
I have a 1000W metal halide for tomato plants and could actually use more than that for just the 6' by 6' area used. The heat from it sure cuts down on the gas bill though, but the hydro is a much more expensive way to heat.
Some of the best local gardens outdoors are produced by those along an area referred here to as "the coves" where the water is quite polluted.
Therefore I can't see what problem you would have using the "waste" RO/DI.

Swim
12/19/2010, 07:38 AM
rodi waste water is also great for washing clothing just collect your waste water and pre fill your washer machine

Yep, we do this with waste water here too. We've had absolutely no problem using the waste water for this purpose.

Virtuoso
12/19/2010, 02:23 PM
If you are growing hydroponic vegetables INDOORS, be prepared for a whopping hydro bill.
I have a 1000W metal halide for tomato plants and could actually use more than that for just the 6' by 6' area used. The heat from it sure cuts down on the gas bill though, but the hydro is a much more expensive way to heat.
Some of the best local gardens outdoors are produced by those along an area referred here to as "the coves" where the water is quite polluted.
Therefore I can't see what problem you would have using the "waste" RO/DI.

Would be doing it outdoors. I am trying to reduce waste, not create it. :)

Yep, we do this with waste water here too. We've had absolutely no problem using the waste water for this purpose.

I plan on using what I can for laundry, just not sure laundry would use up all of it.

I also plan on getting water saving upgrade from Bulk Reef Supply when I order my RODI. http://www.bulkreefsupply.com/store/150-gpd-water-saving-upgrade-kit.html

The hydroponic idea was basically to see if I should set up my RODI outside (under cover) or figure out how to make it work in my bathroom.