Ro vs ro/di

Steve Dillon · Jan 30, 2016

90 min difference right is ro/di. Left is just ro. Had a tds meter on both. Ro/di=0 ppm ro=1 ppm. Give me your opinions.

Sabellafella · Jan 30, 2016

Steve Dillon said:
90 min difference right is ro/di. Left is just ro. Had a tds meter on both. Ro/di=0 ppm ro=1 ppm. Give me your opinions.

I live in ny were after my ro membrane usually runs around 0/1 but phosphate still test high if i dont use the di

Steve Dillon · Jan 30, 2016

Great info.. im going to test phosphate on both units tomorrow. Thank you for your info..

kschweer · Jan 30, 2016

I'm a bit confused. I don't see how running the water through the di stage would slow down production. Production should be dictated by the RO membrane.

joshkirkland83 · Jan 30, 2016

Di is also supposed to remove silicates.

kschweer · Jan 30, 2016

Also without being too technical (because I don't know the technicalities lol) the di removes the Ammonia that is broken from chloramine by the carbon block. @AZDesertRat should be able to shine more light on this than me.

Steve Dillon · Jan 30, 2016

The ro is supposed to be 100 gpd and the ro/di is 75 gpd. But it shouldn't be that much of a difference in 90 mins. All new membrane and filters on ro/di not on ro..

Steve Dillon · Jan 30, 2016

100 gallons per day= 4.17 gallons per hour. 4.17x1.5 hours=6.25 gallons

75 gallons per day= 3.12 gallons per hour. 3.12x1.5 hours= 4.68 gallons

redfishbluefish · Jan 30, 2016

What! What! What??? The rate limiter on RO/DI is the RO membrane. DI does not add any "restriction" to the production of water. 100 gpd out of an RO unit produces 100 gpd out of an RO/DI unit. I'm puzzled by these results. Something not's right.

EDIT TO ADD: I just re-read the thread and now believe you have two different units....one that has a 100 gpd membrane (RO only), and a second unit that has a 75 gpd membrane (RO/DI). Is this the question you are asking....why there is a difference between the two units?

Steve Dillon · Jan 30, 2016

Yes.. 75gpd should be at least 3/4 of what the 100 gpd puts out.. and if I didn't have both.. why should I upgrade 1ppm isnt worth worrying about. Gfo and carbon would take that out.

Steve Dillon · Jan 30, 2016

Input tds is 36 just to add

redfishbluefish · Jan 30, 2016

Here's my recommendation....put the DI unit on the 100 gpd unit and call it a good day!

I'm going to guess that the difference between the two units has to do with the flow restrictor....and how it was cut. It has nothing to do with the DI portion of the units.

Steve Dillon · Jan 30, 2016

I never said it did.. but why buy a di unit for a 1 ppm difference. And not full potential. What real difference is it gonna make?

redfishbluefish · Jan 31, 2016

Well here's my take on this.

I want the purest water I can make for my tank. When water evaporates, the only thing lost is pure water. The "dissovled solids" end up staying behind. Now I have this testing device that only measures down to parts per million. But what do I have if it measured down to parts per billion? Bottom line is that I want the purest water I can produce. 1 ppm is 1000 ppb.

In the winter time, once cranked up and running for a while (about 10-15 minutes), my RO unit is putting out water at 0 TDS. I still run this through DI. Again, I want the purest water I can produce for my tank.

Now, does it make a difference........for the tank, who knows.....but for my mind, it couldn't be happier!

joshkirkland83 · Jan 31, 2016

Steve Dillon said:
I never said it did.. but why buy a di unit for a 1 ppm difference. And not full potential. What real difference is it gonna make?

Because its not just about TDS. The di removes silicates and phosphates. IMO a multi thousand dollar reef isnt worth risking over an RO/DI unit.

Steve Dillon · Jan 31, 2016

Ok but lps/ sps need things to live.. im simply asking is there really a big huge deal.. I dont have a billion gallon tank.. I have both soft and lps corals. I have killed the only 2 sps corals I have ever owned. Is di the reason. Not a witch hunting expo @redfishbluefish!!

Steve Dillon · Jan 31, 2016

But honestly I dont think it is.. 1 ppm and more money for the unit..

Sabellafella · Jan 31, 2016

Steve Dillon said:
Ok but lps/ sps need things to live.. im simply asking is there really a big huge deal.. I dont have a billion gallon tank.. I have both soft and lps corals. I have killed the only 2 sps corals I have ever owned. Is di the reason. Not a witch hunting expo @redfishbluefish!!

The water thats left in the di cartridge "might" add up to the loss in the jug . also that 1 ppm reading i get after flushing my membrane and running the unit without the di shows up completely blue on a salifert test kit for phosphate. Tds were i live is around 30 so di last me quite a while.

kschweer · Jan 31, 2016

Seems to me that your mind is already made up. For what it's worth I would suggest using the di. Here is no way of telling what makes up the 1 tds you have left over. For the relatively low cost of a di why not eliminate it? Also with only 1 tds entering the di stage it should last a considerable amount of time.

joshkirkland83 · Jan 31, 2016

Steve Dillon said:
Ok but lps/ sps need things to live.. im simply asking is there really a big huge deal.. I dont have a billion gallon tank.. I have both soft and lps corals. I have killed the only 2 sps corals I have ever owned. Is di the reason. Not a witch hunting expo @redfishbluefish!!

But why add silicate and phosphate?? Its not that big of a price difference. If you have proper pressure and good filters you should get AT LEAST 1500 gallons out of a set of filters. Not to mention all the algae issues you will have down the road of continous addition of phosphate and silicate.