ReeVo
New Member
I thought this would be helpful to anyone who is considering building a hybrid RO system for drinking water and 0 TDS deionized water for aquarium needs. I haven’t seen any write-ups or examples anywhere, so I thought I would share.
I live in a condo, so I don't really have the luxury of having a dedicated RO/DI unit for my saltwater/top-off needs. So, I had to improvise. Since I already have a RO drinking water system under my kitchen sink, I started drawing up a design for the hybrid system.
I designed this system to produce delicious drinking water and independently produce 0 TDS water in the same system without cross contamination. It works flawlessly and I couldn't be happier how it performs. This is an over-thought, over killed RO system but that's just how I roll. It consists of:
The system utilizes a booster pump because my water pressure sits around 50 psi. To get near full potential of the 99% projected rejection rate of the RO membrane and produce more than 75 gallons per day out of the system, I upped the water pressure to 80 psi. You can go up 90 psi but due to the complexity of the design, I didn't want to push it too far and create a greater risk of leaks. It can produce 5 gallons of RO/DI within 1.25 hours, which is about 96 gallons per day at 80 psi. Not too shabby for a 75-GPD system I will say.
The Aquatec 40 psi pressure switch works in conjunction with the included ASO that comes with the BRS unit. The placement is very important for it to function as intended.
The Aquatec Automatic Flush Valve is a quality-of-life addition and I love it. I used to own a SpectraPure RO/DI unit 10+ years ago and I can’t say how many times I forgot to flush the system before or after use and when I did, the number of times I would leave the flush valve engaged and just waste water. No pun intended lol. I chose the 600mL version, instead of the standard 500mL, due to my high TDS, to flush the RO membrane more aggressively and decrease the amount of TDS creep in the system. It flushes before the booster pump turns on, after the booster pump turns off, and each hour after continuous use.
The first 3 stages all use 1-micron filters. First stage is a 1-micron sediment filter and the second and third stages are 1-micron carbon blocks. The booster pump is placed after the third stage to protect the booster pump from debris getting stuck or damaging the pump over time.
I opted for the 3-stage DI canister setup (part of the BRS 7-Stage RO unit) due to my high TDS. I really like the idea of An-ion and Cat-ion being independent in the first 2 stages and a mixed bed resin of the two resins, as the last stage. I haven’t discovered yet which of the two will be exhausted quicker but something I am curious about. I’m hoping that replacement/repacking the resins will be as infrequent as it seems, especially since I am not producing that much water on a weekly basis for my 20 gallon reef tank.
My wife and I love our pour over and espresso coffees. So, I’m trying a new remineralizer, the Vitev REMIN Ca - RO Remineralization Filter, that has gotten a lot of hype from coffee and drinking water lovers. They also have an alkaline version of the filter that I will try next. I also added a carbon block/water polisher after the mineralizer for taste reasons. This is common practice for drinking water systems. I must say, the water is delicious and very pleasant to drink. We’re like camels in this house. We drink the stuff by the gallon every day.
The ¼” lines are more than sufficient to push water to the very close water faucet and the refrigerator that sits about 12 feet away. Some may think they need 3/8” lines but unless you’re pumping water 25+ feet away, ¼” is fine.
A leak detector is something I cannot stress enough for an under-sink RO system. This will turn a disastrous situation into a light clean up. It’s cheap and it doesn’t rely on electronics to shut the system off.
The check valves have been meticulously placed for proper flow direction. Without them, you risk cross contamination of the system or higher than post RO membrane water entering the DI stages. I have added a couple of redundant ball valves, just in case if the check valve fails, I don’t want to risk exhausting the DI resins prematurely. The ball valve before entering the DI stage is redundant to the ball valve after the DI stages but the reason for it is simple. When the system is being pressurized by the booster pump, it is also pressurizing the DI canisters. Excess pressure that is not necessary and reduces the risk of leaks.
Some might ask, why am I using polyurethane tubing and where. It is only being used after the DI stages (light blue tubing in image) for ease of maneuvering the hose into a bucket and storing away after use. The standard Polyethylene tubing is quite rigid and difficult to maneuver. It can handle pressures above 250 psi and is hard enough to be used in push-connect fittings. Hence why I added a ball valve before the DI stages to avoid pressurizing the DI housings and polyurethane tubing.
The tubing is color coded for water type:
I hope this is helpful to some who are also interested in building a similar system under their kitchen sink or elsewhere.
I live in a condo, so I don't really have the luxury of having a dedicated RO/DI unit for my saltwater/top-off needs. So, I had to improvise. Since I already have a RO drinking water system under my kitchen sink, I started drawing up a design for the hybrid system.
I designed this system to produce delicious drinking water and independently produce 0 TDS water in the same system without cross contamination. It works flawlessly and I couldn't be happier how it performs. This is an over-thought, over killed RO system but that's just how I roll. It consists of:
- BRS 75-GPD 7-Stage RO/DI system
- Aquatec CDP 8800 Booster Pump
- Aquatec 600mL Automatic Flush Valve
- Aquatec 40 PSI Pressure Switch
- 3.2 Gallon RO Water Storage Pressurized Tank (at 7 psi)
- Vitev REMIN Ca - RO Remineralization Filter (For drinking water ONLY)
- Omnipure Inline Carbon Block (For drinking water ONLY)
- 1/4" Mur-Lok and John Guest fittings
- 1/4" Mur-Lok Polyethylene RO tubing
- 1/4" Parker Polyurethane Tubing
The system utilizes a booster pump because my water pressure sits around 50 psi. To get near full potential of the 99% projected rejection rate of the RO membrane and produce more than 75 gallons per day out of the system, I upped the water pressure to 80 psi. You can go up 90 psi but due to the complexity of the design, I didn't want to push it too far and create a greater risk of leaks. It can produce 5 gallons of RO/DI within 1.25 hours, which is about 96 gallons per day at 80 psi. Not too shabby for a 75-GPD system I will say.
The Aquatec 40 psi pressure switch works in conjunction with the included ASO that comes with the BRS unit. The placement is very important for it to function as intended.
The Aquatec Automatic Flush Valve is a quality-of-life addition and I love it. I used to own a SpectraPure RO/DI unit 10+ years ago and I can’t say how many times I forgot to flush the system before or after use and when I did, the number of times I would leave the flush valve engaged and just waste water. No pun intended lol. I chose the 600mL version, instead of the standard 500mL, due to my high TDS, to flush the RO membrane more aggressively and decrease the amount of TDS creep in the system. It flushes before the booster pump turns on, after the booster pump turns off, and each hour after continuous use.
The first 3 stages all use 1-micron filters. First stage is a 1-micron sediment filter and the second and third stages are 1-micron carbon blocks. The booster pump is placed after the third stage to protect the booster pump from debris getting stuck or damaging the pump over time.
I opted for the 3-stage DI canister setup (part of the BRS 7-Stage RO unit) due to my high TDS. I really like the idea of An-ion and Cat-ion being independent in the first 2 stages and a mixed bed resin of the two resins, as the last stage. I haven’t discovered yet which of the two will be exhausted quicker but something I am curious about. I’m hoping that replacement/repacking the resins will be as infrequent as it seems, especially since I am not producing that much water on a weekly basis for my 20 gallon reef tank.
My wife and I love our pour over and espresso coffees. So, I’m trying a new remineralizer, the Vitev REMIN Ca - RO Remineralization Filter, that has gotten a lot of hype from coffee and drinking water lovers. They also have an alkaline version of the filter that I will try next. I also added a carbon block/water polisher after the mineralizer for taste reasons. This is common practice for drinking water systems. I must say, the water is delicious and very pleasant to drink. We’re like camels in this house. We drink the stuff by the gallon every day.
The ¼” lines are more than sufficient to push water to the very close water faucet and the refrigerator that sits about 12 feet away. Some may think they need 3/8” lines but unless you’re pumping water 25+ feet away, ¼” is fine.
A leak detector is something I cannot stress enough for an under-sink RO system. This will turn a disastrous situation into a light clean up. It’s cheap and it doesn’t rely on electronics to shut the system off.
The check valves have been meticulously placed for proper flow direction. Without them, you risk cross contamination of the system or higher than post RO membrane water entering the DI stages. I have added a couple of redundant ball valves, just in case if the check valve fails, I don’t want to risk exhausting the DI resins prematurely. The ball valve before entering the DI stage is redundant to the ball valve after the DI stages but the reason for it is simple. When the system is being pressurized by the booster pump, it is also pressurizing the DI canisters. Excess pressure that is not necessary and reduces the risk of leaks.
Some might ask, why am I using polyurethane tubing and where. It is only being used after the DI stages (light blue tubing in image) for ease of maneuvering the hose into a bucket and storing away after use. The standard Polyethylene tubing is quite rigid and difficult to maneuver. It can handle pressures above 250 psi and is hard enough to be used in push-connect fittings. Hence why I added a ball valve before the DI stages to avoid pressurizing the DI housings and polyurethane tubing.
The tubing is color coded for water type:
- Red for feed water
- Black for wastewater
- White for drinking water
- Blue for deionized water
- TDS-1: 400-450
- TDS-2: 10-12
- TDS-3: 25-36
- TDS-4: 0
- TDS-5: 0
I hope this is helpful to some who are also interested in building a similar system under their kitchen sink or elsewhere.
