Your opinion please, RO/DI needed

srusso · 08/27/2010, 11:43 AM

So I have been researching RO/DI systems and read that most systems have a 98% rejection rate!!! That's crazy! For my weekly water changes I plan to do 15 gallons a week, that means I would have wasted 150 gallons to make the 15 of RO/DI water. Knowing that my city water happens to be of a very high quality.

So I tested my tap and it was between 0 - 0.03 phosphates. I then tested my healthy fresh water planted tank to get a base line of something that I know should have phosphates. It tested at 1... Which from my research is normal for a healthily planted tank. So once I get my TDS meter, assuming it tests well... Could I use tap and skip the RO/DI? Or is there another test that my tap should pass before considering this... I understand that most here feel that RO/DI is a must, but I like to be sure before buying something I may not really need.

Other tap info:
pH. 6.8
Ammonia 0
Nirites 0
Nitrates. 0

ferret768 · 08/27/2010, 12:00 PM

I would say that it depends on your setup, what you plan to keep/grow, and your source water quality. Provided your tank will just be a hobby tank with softies or LPS, a decent filter setup might do everything you want it to. If you will be growing a lot of SPS, fragging, or want an immaculate reef display RO/DI might be a good choice. I have similar water quality locally and have had great success using tap water, and running a good skimmer, Chemipure elite in the trickle filter, and GFO media in a reactor. also bear in mind that there can be a lot of other nasty junk in tap water than what you've tested for. Your local water authority can supply you with a free report detailing all the pollutants in your water, you might be surprised what's there. Lastly there are some higher RO units that produce a 1:1 treated to waste water ratio (those with auxiliary pumps) if you're worried about wasting water you might look into those.

fcmatt · 08/27/2010, 12:15 PM

Consider this if you care to:

Tap Water Filter (Aquarium Pharmaceuticals)
http://aquariumpharm.com/Products/Pr...x?ProductID=97

If your tap water is pretty darn good it should easily make a 150 gallons.
About 40-50 dollars to buy the complete unit and then refills are about
20-25 dollars.

No waste water at all. Basically it is a DI stand alone unit. 10 weeks of
cleaner water will cost about 20 bucks...

just a suggestion... naturally you could just buy a standard DI unit and do the
work yourself to save money. I have seen the unit above for sale for years and
someone must be buying them.

thegrun · 08/27/2010, 12:25 PM

Quote:

Originally Posted by srusso

So I have been researching RO/DI systems and read that most systems have a 98% rejection rate!!! That's crazy! For my weekly water changes I plan to do 15 gallons a week, that means I would have wasted 150 gallons to make the 15 of RO/DI water. Knowing that my city water happens to be of a very high quality.

So I tested my tap and it was between 0 - 0.03 phosphates. I then tested my healthy fresh water planted tank to get a base line of something that I know should have phosphates. It tested at 1... Which from my research is normal for a healthily planted tank. So once I get my TDS meter, assuming it tests well... Could I use tap and skip the RO/DI? Or is there another test that my tap should pass before considering this... I understand that most here feel that RO/DI is a must, but I like to be sure before buying something I may not really need.

Other tap info:
pH. 6.8
Ammonia 0
Nirites 0
Nitrates. 0

There are a lot of other tap water concerns beyond phosphates (heavy metals, nitrates, chlorine...). Also remember that you are adding phosphates every time you top off your tank if you use your tap water (they do not evaporate), so after just a few weeks you will have significantly raised your phosphate level.

PurdueWaterGuy · 08/27/2010, 01:49 PM

Rejection rate refers to what percentage of the ions don't make it thru the membrane.

Recovery ratio refers to amount of permeate divided by the amount of feed water used.

silverwolf72 · 08/27/2010, 02:08 PM

98% means for TDS of 100 coming in you will have 2 coming out.
A ro/di is the best way to go even with good city water quality.

WarrenG · 08/27/2010, 02:11 PM

I think my RODI unit sends about 60-70% of the water down the waste line.

IAReefer · 08/27/2010, 02:48 PM

Quote:

Originally Posted by WarrenG

I think my RODI unit sends about 60-70% of the water down the waste line.

WarrenG,

You are correct for the most part. There are ways to minimze this waste and one of them is making sure your using the RO at the optimal pressue, which is usually 60-75PSI. This will make your RO system rum more efficiently, thus reducing waste water and increasing your GPD output. If your not at 60psi, i suggest getting an RO booster pump.

Mavrk · 08/27/2010, 03:39 PM

Quote:

Originally Posted by IAReefer

WarrenG,

You are correct for the most part. There are ways to minimze this waste and one of them is making sure your using the RO at the optimal pressue, which is usually 60-75PSI. This will make your RO system rum more efficiently, thus reducing waste water and increasing your GPD output. If your not at 60psi, i suggest getting an RO booster pump.

90 psi is actually even better. I wish I could find the chart of psi to efficiency. I agree... get a booster pump.

Denbf58 · 08/27/2010, 04:32 PM

for the first two years of my tank where run with tap water filter until I bought a tds meter and found out how soon i was having to replace the filters one word of advise
the slower you run the the longer it lasts .

08/27/2010, 11:43 AM	#1
srusso Registered Member Join Date: Jul 2010 Location: Bridgeport, CT Posts: 1,869	Your opinion please, RO/DI needed So I have been researching RO/DI systems and read that most systems have a 98% rejection rate!!! That's crazy! For my weekly water changes I plan to do 15 gallons a week, that means I would have wasted 150 gallons to make the 15 of RO/DI water. Knowing that my city water happens to be of a very high quality. So I tested my tap and it was between 0 - 0.03 phosphates. I then tested my healthy fresh water planted tank to get a base line of something that I know should have phosphates. It tested at 1... Which from my research is normal for a healthily planted tank. So once I get my TDS meter, assuming it tests well... Could I use tap and skip the RO/DI? Or is there another test that my tap should pass before considering this... I understand that most here feel that RO/DI is a must, but I like to be sure before buying something I may not really need. Other tap info: pH. 6.8 Ammonia 0 Nirites 0 Nitrates. 0

08/27/2010, 01:49 PM	#5
PurdueWaterGuy Registered Member Join Date: May 2010 Location: Lafayette, IN Posts: 196	Rejection rate refers to what percentage of the ions don't make it thru the membrane. Recovery ratio refers to amount of permeate divided by the amount of feed water used. __________________ Tim @ home, 90 gallon tank, dry, waiting for the remodelling to be over @ work, 19,000 gallon per day RO, Electrodeionization, Vacuum Degas, 90 cubic feet DI resin - I love my job! Current Tank Info: dry, kind of dusty :-(

08/27/2010, 04:32 PM	#10
Denbf58 Registered Member Join Date: Mar 2008 Location: selden N.Y. Posts: 885	for the first two years of my tank where run with tap water filter until I bought a tds meter and found out how soon i was having to replace the filters one word of advise the slower you run the the longer it lasts . __________________ Life is good Current Tank Info: 75gal reef ready koralia 3, 30g sump, 4b 48" t5s lighting, 29g reef with breeding pair clowns 55g reef 55g freshwater

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08/27/2010, 12:00 PM	#2
ferret768 Registered Member Join Date: Jan 2009 Posts: 35	I would say that it depends on your setup, what you plan to keep/grow, and your source water quality. Provided your tank will just be a hobby tank with softies or LPS, a decent filter setup might do everything you want it to. If you will be growing a lot of SPS, fragging, or want an immaculate reef display RO/DI might be a good choice. I have similar water quality locally and have had great success using tap water, and running a good skimmer, Chemipure elite in the trickle filter, and GFO media in a reactor. also bear in mind that there can be a lot of other nasty junk in tap water than what you've tested for. Your local water authority can supply you with a free report detailing all the pollutants in your water, you might be surprised what's there. Lastly there are some higher RO units that produce a 1:1 treated to waste water ratio (those with auxiliary pumps) if you're worried about wasting water you might look into those.

08/27/2010, 12:15 PM	#3
fcmatt Registered Member Join Date: Dec 2006 Location: NH Posts: 850	Consider this if you care to: Tap Water Filter (Aquarium Pharmaceuticals) http://aquariumpharm.com/Products/Pr...x?ProductID=97 If your tap water is pretty darn good it should easily make a 150 gallons. About 40-50 dollars to buy the complete unit and then refills are about 20-25 dollars. No waste water at all. Basically it is a DI stand alone unit. 10 weeks of cleaner water will cost about 20 bucks... just a suggestion... naturally you could just buy a standard DI unit and do the work yourself to save money. I have seen the unit above for sale for years and someone must be buying them.

08/27/2010, 02:08 PM	#6
silverwolf72 Registered Member Join Date: Jul 2005 Location: Lake Forrest CA Posts: 1,732	98% means for TDS of 100 coming in you will have 2 coming out. A ro/di is the best way to go even with good city water quality.

08/27/2010, 02:11 PM	#7
WarrenG Registered Member Join Date: Jun 2003 Location: Sunnyvale, CA Posts: 738	I think my RODI unit sends about 60-70% of the water down the waste line.