Reverse Osmosis system recommedation

[lepa71]

Hi All

I have an old Microline TFC 45 4 stage system with 45 GPD for the last 19 years. I'm on city water that is not so good and I already have a good water softener. Most of the quick-connect fitting now leaking and need new filters. So I was thinking I would just get a new system. There are quite a few systems on amazon and eBay. They all look the same. Some with 50 GPD or 75 GPD. I don't think I would need to go for 100 GPD. My current system has 1/4 for water supply but the rest of the tubes are 3/8. Also, it is connected to my fridge ice maker via a 3/8 tube.
So here are some questions

1. 50 GPD vs 75 GPD?
2. 3/8 vs 1/4? This may not be that important but it could be.
   
3. Some 6 or 10 stage system includes pH mineral filter. Should I look at those or just stay with 5 stage system? 5 stage systems are a little bit more acidic. I believe having some minerals is a good thing.
4. Some systems have 2nd carbon filter after mineral filters and some just end with mineral filters. Some people report that the systems with the last filter being mineral have bad taste and it takes a long time to get rid of it. Any suggestions?
5. Any other suggestions?

Thanks in advance.

 

[Taylorjm]

The big thing with ro systems is incoming water pressure. RO systems need high pressure to work efficiently. I'm talking about anywhere between 80-100psi or even more for some systems. That makes water faster but also with a lot less waste water. Instead of wasting 4 gallons of water for every 1 gallon ro water, increasing the pressure can get it closer to 1:1 or 1:2. It also provides more output water pressure in your external tank to add things like ice makers or water dispensers in refrigerators. Most of the time the pressure is increased by using an electric pump attached to the ro system. This requires you to have electricity under the sink or wherever the ro system is located. There's also what's called a permeate pump which doesn't require electricity. Instead if harnesses pressure from the waste water to provide more pressure to the incoming water, but they can also be noisy and make a clicking sound. As far as adding minerals, that's up to you. RO systems strip everything from the water. They also decrease the ph value, which makes it more acidic. That's why you need to make sure you don't have any copper piping running any RO water. The higher acid level will leech the copper out into the water. With an ice maker, it probably won't be enough to bother with, but also why you can't have a whole house RO system with copper piping, unless you increase the ph so it won't leech the copper.

I have an undersink ro system in my lake house with well water. I was going to replace it and would definitely go with a larger system, like about 100gpd and a high pressure electric pump. We have 2 small 4 gallon pressure tanks under the sink because the wife and kids drink a lot of water, but I'd really like a pressure increase because it's barely enough pressure to run the ice maker. I've been using the ispring models and have been happy with them but was looking at other models too with a high pressure pump.

 

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[lepa71]

My water pressure is about 65. So I'm ok with that part. I don't think we use more than 50 gpd today. So I'm not sure if I really need a 100 gpd. Some people saying that decreasing wastewater ration would decrease the filtering capabilities of RO. So 75gpd should be than enough. I wish I could do the whole house 1M gallons system but I just don't have space for it. My ice maker uses a plastic tube. It replaced the cooper one when the RO system got installed.

 

[Reach4]

My water pressure is about 65. So I'm ok with that part. I don't think we use more than 50 gpd today. So I'm not sure if I really need a 100 gpd.

I would suggest that you get one with a bigger tank. Also get the permeate pump.

 

[Taylorjm]

My water pressure is about 65. So I'm ok with that part. I don't think we use more than 50 gpd today. So I'm not sure if I really need a 100 gpd. Some people saying that decreasing wastewater ration would decrease the filtering capabilities of RO. So 75gpd should be than enough. I wish I could do the whole house 1M gallons system but I just don't have space for it. My ice maker uses a plastic tube. It replaced the cooper one when the RO system got installed.

You do realize that when they say 50 gpd, they don't actually mean that's what it produces right? That's under ideal conditions and higher water pressures. Your 65 psi is adequate, but still low for a ro system.

 

[Taylorjm]

I would suggest that you get one with a bigger tank. Also get the permeate pump.

So I wonder about the permeate pump part. From what I was researching, they do work well, but I heard many people complain they were extremely noisy. Lots of clicking and clacking. What do you think when compared to a high pressure pump?

 

[Bannerman]

The daily output rating for the membrane is based on various factors including specific incoming water pressure, water temperature, and no backpressure placed on the membrane from RO water in storage.

Without a permeate pump, the pressure of the RO water in storage (permeate) is typically configured to not exceed 60% of incoming water pressure. If the incoming pressure is increased with an electric pump, then the storage pressure will also increase by the same 60% ratio. If the storage pressure was to be further exceeded without increasing the incoming pressure, the resulting backpressure from the RO storage tank will further reduce efficiency due to increased back pressure on the membrane which will continue to reduce production output as the storage tank continues to fill. Since rejection flow (brine) which you call 'waste' is utilized for flushing the membrane and is configured to flow at a constant rate, the ratio of wastewater compared to permeate will be further increased.

A permeate pump is not electrically operated but is 'powered' by brine (waste) flow. As the suction side to the PP is connected to the membrane's permeate output connection, the PP will pump permeate directly from the membrane to storage without backpressure being placed on the membrane, thereby allowing a higher pressure differential through the membrane, resulting in a significant improvement to the membrane's efficiency.

As the membrane efficiency is improved, storage tank recovery will be more rapid, thereby reducing the total operating time needed by the system each day vs the same production quantity without a PP. Even as a PP will often produce some noise while operating, the system run time will be much less than without a PP, thereby potentially reducing the significance of any noise.

As the run time will be reduced, so too will the total amount of wastewater since the waste flow will cease once the storage tank becomes filled. Because the membrane output will be consistent whether the storage tank is empty, 1/2 full or 99% full, the storage pressure may often be increased to 90% of incoming pressure.

 

[lepa71]

So how is this looking? https://www.amazon.com/dp/B07JPKZCDX/ref=twister_B07KSM5BR8?_encoding=UTF8&psc=1

 

[Taylorjm]

So how is this looking? https://www.amazon.com/dp/B07JPKZCDX/ref=twister_B07KSM5BR8?_encoding=UTF8&psc=1

It's hard to say. What is your incoming water pressure? What pressure does the pump pressurize incoming water to? Many systems with an electric pump are made to increase low incoming water pressure. So if your incoming pressure is 40psi then you need the pump that may only operate to 60psi. If your incoming water is 60psi then that pump won't help. If the pump takes the working pressure up to 80-100psi, then yes, it will make a big difference in your faucet pressure and less waste water. All depends on the psi that the electric pump shuts off at.

 

[Taylorjm]

There are a couple of picture that show the psi gauge at 110psi, and it looks like it's measuring pressure going into the membrane. So if that's true and the pump is pressurizing the membrane at 110psi, that would be pretty good.