High capacity RODI?
- Thread starter Armando
- Start date
toothman
Premium Member
My tap is well water, it has 600 ppm and runs through my 65gpd kent ro di plus a extra di, it usually comes out with less than 5ppm when done with a absolute new cartridge in one it is close to 0. I like this method but more water quicker sounded nice but too much ppm for me.
AZDesertRat
In Memoriam
You should be getting better water than that. My raw water Saturday was 627, after RO only it was 11 and after a single vertical 24 oz refillable DI with almost 200 gallons of usage on it it is still 0. I will admit its just about time to change the resin, I usually get 200 to 2500 gallons per 24 oz refill before I see it creep up to between 2 and 3 which is my trigger point. My membrane is 2 years old and has seen lots of use between drinking water, ice maker, pet water and aquariums.
moonpod
Premium Member
toothman, even with a 90% extraction membrane you should be below 60 out of the RO membrane and 0 with a DI. A 98% should give numbers like what AZ rat is giving. The number one factor for protecting your membrane is limited chloring exposure to the membrane.
For most people, I agree that a dual 75 gpd unit is probably the best way to go.
What is impressive about the Merlin is that it really still works well at relatively low pressures obviating the need for a pump to optimize the performance.
For most people, I agree that a dual 75 gpd unit is probably the best way to go.
What is impressive about the Merlin is that it really still works well at relatively low pressures obviating the need for a pump to optimize the performance.
AZDesertRat
In Memoriam
You might for awhile but I am aure your Spectrapure has a 98% rejection membrane and the Merlin will not do that well. Your DI resin will not last near as long.
What is your RO only TDS now? I would think its about 3 or 4 with a Spectrapure.
You can safely assume your RO (Merlin) only TDS would be in the 17 to 20 range if your raw water TDS is about 170 with the new unit. At that rate DI will exhaust 4 to 5 times faster gallon per gallon.
What is your RO only TDS now? I would think its about 3 or 4 with a Spectrapure.
You can safely assume your RO (Merlin) only TDS would be in the 17 to 20 range if your raw water TDS is about 170 with the new unit. At that rate DI will exhaust 4 to 5 times faster gallon per gallon.
AZDesertRat
In Memoriam
Moonpod you are giving misleading answers to his questions. Give him a complete honest answer.
Again the answer is you will get 0 TDS for a time but it will be about 4 or 5 times shorter DI life for the same given amount of water. Yes it will make water much faster, and yes you can achieve 0 TDS but you will need to change resin out much more often. DI resin has a finite capacity so if the incoming TDS is higher the life is shorter.
You would probably still be better of with multiple "high rejection" 75 GPD membranes rather than multiple "high capacity" membranes like the Merlin uses.
Again the answer is you will get 0 TDS for a time but it will be about 4 or 5 times shorter DI life for the same given amount of water. Yes it will make water much faster, and yes you can achieve 0 TDS but you will need to change resin out much more often. DI resin has a finite capacity so if the incoming TDS is higher the life is shorter.
You would probably still be better of with multiple "high rejection" 75 GPD membranes rather than multiple "high capacity" membranes like the Merlin uses.
moonpod
Premium Member
As I stated previously most people are better off with dual 75 gpd membranes (look at a few posts up). However the 75 gpd membranes IME are much more pressure sensitive than the Merlin. Trust me on this. The merlin is very insensitive to pressure. I need a permeate pump to get good production with my current water pressure and a standard ro unit.
he asked if a merlin will work and yes it will.
he asked if a merlin will work and yes it will.
AZDesertRat
In Memoriam
So would a cheap Filter Direct unit but both at a cost. The cost being lower efficiency and increased operating costs due to shortened DI life.
moonpod
Premium Member
Whatever dude, I'm not going to argue with you. These are not "standard" 100gph membranes in the Merlin. The "sweetpoint" for Dow membranes is definitely the 75 gpd membranes. The Merlin is a up to 700 gpd unit, which is prohibitively expensive using 75 gpd units--and for darn sure I filled my 500+ gallon system in much less than a day. I run through a lot of water and I suppose I don't get the DI life I could, but oh well.
Ixthys do what you will.
Ixthys do what you will.
purelyh2o
New member
The reason
The reason
The reason the Merlin system is able to produce high output at low pressure is due to the looser wound membrane colums which increases the allowable pass through and can essentialy give out the name easily permeated membrane
instead of semi permeable. I think it is a great system for drinking water systems or situations with high TDS but unfortunately I could not endorse it for Aquarium use. Otherwise I would stock it. It just doesnt pass the buck for me.
The reason
The reason the Merlin system is able to produce high output at low pressure is due to the looser wound membrane colums which increases the allowable pass through and can essentialy give out the name easily permeated membrane
instead of semi permeable. I think it is a great system for drinking water systems or situations with high TDS but unfortunately I could not endorse it for Aquarium use. Otherwise I would stock it. It just doesnt pass the buck for me.
purelyh2o
New member
Membranes
Membranes
The addition of 2 or 3 membranes together would have to split the incoming pressure 3 ways and bring the face pressure on the membranes much lower than needed. This would cause each membrane to terribly underproduce and as a result ALOT of waste water. Definitely use the 75 gpd membrane and definitely add a booster pump. I think you will be very happy with the results. Another thing is that you will need to implement a method of adjusting the waste rejection rate based on the overall output of the system. 3 to 1 would be fine
Membranes
The addition of 2 or 3 membranes together would have to split the incoming pressure 3 ways and bring the face pressure on the membranes much lower than needed. This would cause each membrane to terribly underproduce and as a result ALOT of waste water. Definitely use the 75 gpd membrane and definitely add a booster pump. I think you will be very happy with the results. Another thing is that you will need to implement a method of adjusting the waste rejection rate based on the overall output of the system. 3 to 1 would be fine
AZDesertRat
In Memoriam
Yes. What you have is a capillary type restrictor, there are also some that use an orfice like I use and others that use an adjustable needle valve that you can adjust to suit your needs. My water temperature and pressure don't fluctuate much season to season so I use the orfice which I personally like better than the capillary tube which you trim to fit or the valve you adjust. All work just fine though.
AZDesertRat
In Memoriam
No its a small orfice disc inside a housing which fits inline with john guest fittings.
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