How can I justify RODI Unit?

akabryanhall

2500 Club Member
View Badges
Joined
Jun 17, 2009
Messages
2,925
Reaction score
181
Rating - 0%
0   0   0
I have an rodi unit that came with my tank, and I am a little wary of it. I have changed the filters, but my tds meter is shot, and I have no way of telling how old the membrane is, or what my water reading is. That is not my main concern however.
I have my water draining into a 32 gallon bin. If I am optimistic, I would say that I have a 5% pure to 95% waste, so if I want to fill up that bin just once, I waste a little under 700 gallons of water. That aint right. My water bill would not justify using that amount of water when I can get 5 gallons of good water for a buck 75 could it?
To put this in perspective, in a 10 minute shower, you can use UP TO 42 gallons of water, depending on water pressure. Lets take the higher end of that and say 40 gallons. Filling my bin up once is like taking 17 ten minute showers, or one 3 hour shower.

I don't have a way of recycling the water back into irrigation or something, just aint an option. A perfect world could have me cycle the waste water back into the filtration again and again.
 
Last edited:

Sikryd

hmm...Sweet!
View Badges
Joined
Feb 19, 2009
Messages
2,321
Reaction score
14
Location
MD
Rating - 0%
0   0   0
You probably need a booster pump to raise the pressure and reduce the waste water.
What is your line pressure now? In the 60-80 range RODI's become more efficient. Throw another membrane on and it REALLY reduces waste. It ends up paying for itself depending on how much water you make.

Sounds like your line pressure is low going into the RODI
 

dbarker

Active Member
View Badges
Joined
Jan 24, 2007
Messages
270
Reaction score
1
Location
Anniston, Alabama
Rating - 0%
0   0   0
OK...buy the time I have to drive to my lfs, carry 4 7 gallon water containers into the store, wait on someone to fill them for me, carry them out and now they are really heavey, drive back home, unload them and now I can start mixing and testing water for only ONE tank! I currently have 3 tanks running. YES it is worth it!

About the waste water, I too was very concerned with the amount of water I was wasting, so I drain my waste water into my washing machine and wash clothes with it. I use a brute container by the washer and the ro water goes in there and when the washer is full I just roll the brute out of the way.

That is some trouble to say the least, but much less than going to my lfs. A friend boosted my 35 gal/day RO unit to a 75gal/day and it makes collecting water much easier. With the 35 gal/day I would turn on the RO unit when I went to bed and the washer was full when I got up. Now the 75 unit will fill the washer in about 4 hours.

Of course, it is your personal choice and what works best for you. Having my RO unit at home has worked well for me. Hope that helps! Debbie
 

addicted4life

Community Member
View Badges
Joined
May 10, 2009
Messages
34
Reaction score
0
Location
Indianapolis, IN
Rating - 0%
0   0   0
RODI unit is probably the largest time saver in reef keeping in my opinion. Makes water changes a breeze, therefore you will do it more. Change that dirty membrane ! and get an inline tds meter that measures tds coming in, and going out of the rodi unit.
 

Psychographic

Active Member
View Badges
Joined
Oct 29, 2006
Messages
141
Reaction score
5
Rating - 0%
0   0   0
Throw another membrane on and it REALLY reduces waste. It ends up paying for itself depending on how much water you make.

Do you mean Filter>Carbon Block>Membrane>Membrane>DI ?

If so how are how you hooking up the second membrane? To the waste from the first Membrane, then Teeing the good output of the second Membrane to the good output of the first Membrane?
 

AZDesertRat

5000 Club Member
View Badges
Joined
Feb 25, 2009
Messages
5,090
Reaction score
1,323
Location
Phoenix AZ
Rating - 0%
0   0   0
Second membranes are not water savers. Those who promote them as such are incorrect. Take it from vendors such as Spectrapure, PurelyH2O and AWI who have been in business for years and years and do not make false or questionable claims when it comes to water savings.

In order to keep a membrane functional you MUST keep it well flushed. This flushing is accomplished by the 4:1 waste ratio which results when you install a flow restrictor in the waste line.

By doubling up membranes you increase production but you must still keep the membrane flushed and the second membrane in a dual setup is fed by the waste from the first so must be flushed just as well if not better.

The only real water saving system viable for our hobby is the Spectrapure MaxCap UHE which has a 1:1 waste ratio or slightly less if you have low TDS water to begin with. Thats what I use myself but most cannot justify the price until they do the long term math. Thye did a bunch of engineering to make this system work and last and its the only one of its kind that really works and works well. Others are attempting to copy it but none is worth the money so far.

You can use the waste to water the grass, landscape, wash clothes, fill the pool etc. I myself am not so concerned since all water has been around for millions of years and gets recycled over and over, its not like it goes away when we waste it.
 
Back
Top