Affect wrong size flow restrictor has on TDS after RO membrane.

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I have a Aquamaxx Puratek 100gpd RO/DI filter. Today I added new DI resin and a Pentair ChlorPlus cartridge because I have chloramines. My pressure gauge reads 80psi. It's a five stage with a 5 micron sediment filter, a five micron carbon block, a 1 micron chloramine block, 100gpd membrane and lastly DI. My incoming TDS is 450ish (varies a bit). After changing DI and adding the additional carbon block my TDS after membrane is 34 and after DI is 4. The unit came with a factory installed 550 flow restrictor. Shouldn't it be an 800? If I changed to an 800 would that reduce the TDS after the RO. Sorry for the long winded post. Thanks for reading.
 

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I have a Aquamaxx Puratek 100gpd RO/DI filter. Today I added new DI resin and a Pentair ChlorPlus cartridge because I have chloramines. My pressure gauge reads 80psi. It's a five stage with a 5 micron sediment filter, a five micron carbon block, a 1 micron chloramine block, 100gpd membrane and lastly DI. My incoming TDS is 450ish (varies a bit). After changing DI and adding the additional carbon block my TDS after membrane is 34 and after DI is 4. The unit came with a factory installed 550 flow restrictor. Shouldn't it be an 800? If I changed to an 800 would that reduce the TDS after the RO. Sorry for the long winded post. Thanks for reading.
A 100 gpd RODI unit should have come with an 800 flow restrictor. I'd contact the manufacturer.
 

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I have a Aquamaxx Puratek 100gpd RO/DI filter. Today I added new DI resin and a Pentair ChlorPlus cartridge because I have chloramines. My pressure gauge reads 80psi. It's a five stage with a 5 micron sediment filter, a five micron carbon block, a 1 micron chloramine block, 100gpd membrane and lastly DI. My incoming TDS is 450ish (varies a bit). After changing DI and adding the additional carbon block my TDS after membrane is 34 and after DI is 4. The unit came with a factory installed 550 flow restrictor. Shouldn't it be an 800? If I changed to an 800 would that reduce the TDS after the RO. Sorry for the long winded post. Thanks for reading.
I believe Puratek goes for a lower waste ratio of around 2 to 1 which may be why they include the 550. Depending on age and what is in your water, it could also be clogging up. You never say the age of your ro membrane but it is sounding like it may need replacing since you are only seeing around a 92% rejection rate. I used to use a 550 with my 90gpd unit with no tds issues. Really hard to answer since water temperature and your water pressure also have a hand in your good water tds.

It does sound like you have another issue since you are getting 4 after the di. Either your tds meter is off or you didn't pack the di down good enough when filling the cartridge (assuming you did it yourself).
 
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I believe Puratek goes for a lower waste ratio of around 2 to 1 which may be why they include the 550. Depending on age and what is in your water, it could also be clogging up. You never say the age of your ro membrane but it is sounding like it may need replacing since you are only seeing around a 92% rejection rate. I used to use a 550 with my 90gpd unit with no tds issues. Really hard to answer since water temperature and your water pressure also have a hand in your good water tds.

It does sound like you have another issue since you are getting 4 after the di. Either your tds meter is off or you didn't pack the di down good enough when filling the cartridge (assuming you did it yourself).
The unit has only been in use for two months. Purchased brand new. The cartridge was purchased pre packed from aquatic life.
 

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The unit has only been in use for two months. Purchased brand new. The cartridge was purchased pre packed from aquatic life.
Well then something is wrong. I get 4 to 5 tds after my ro membrane and my tap water is over 400. Even at your 34 before the di, you should get around 130 gallons of 0 tds water before the di is exhausted. I'm not sure a different flow restrictor is going to make that big of an improvement in your tds after your membrane.

You might try reseating the ro membrane in the ro housing to just make sure it is seated correctly.

Another possibility is the tds meter is bad. I assume it has a built in tds meter. You could invest in a handheld. It is all I use personally.
 
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Well then something is wrong. I get 4 to 5 tds after my ro membrane and my tap water is over 400. Even at your 34 before the di, you should get around 130 gallons of 0 tds water before the di is exhausted. I'm not sure a different flow restrictor is going to make that big of an improvement in your tds after your membrane.

You might try reseating the ro membrane in the ro housing to just make sure it is seated correctly.

Another possibility is the tds meter is bad. I assume it has a built in tds meter. You could invest in a handheld. It is all I use personally.
I've pulled and reinstalled the membrane and it's installed correctly. Possibly need to replace the membrane. I'm a bit baffled at this point. My TDS meter is the HW (I believe that's the brand). I'll probably get some calibration fluid. I'll look into the handheld unit.
 
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The curve is fairly flat until you go to far see Fig 1.8. I check my recovery rate in the summer whne my incoming water is the warmest knowing in the winter my recovery rate will go down.

1649157462065.png

1649157622664.png
 

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I have a Aquamaxx Puratek 100gpd RO/DI filter. Today I added new DI resin and a Pentair ChlorPlus cartridge because I have chloramines. My pressure gauge reads 80psi. It's a five stage with a 5 micron sediment filter, a five micron carbon block, a 1 micron chloramine block, 100gpd membrane and lastly DI. My incoming TDS is 450ish (varies a bit). After changing DI and adding the additional carbon block my TDS after membrane is 34 and after DI is 4. The unit came with a factory installed 550 flow restrictor. Shouldn't it be an 800? If I changed to an 800 would that reduce the TDS after the RO. Sorry for the long winded post. Thanks for reading.

My Puratek 100gpd RO/DI came with a 450 restrictor installed from the factory.
20220411_205634.jpg
 
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Vendors know that users want less "waste water" (a.k.a. concentrate) so without any knowledge of the user's water chemistry some vendors (often claiming some sort of magic membrane) drastically restrict the concentrate flow to come up with a 1:1 ratio or something similar.

Here's the thing: if you have no water hardness - then sure, use a tighter flow restrictor to give you a 1:1. If you have hardness in your water (almost everyone does) you'll reduce the lifespan of your membrane because that hardness will deposit as scale inside the membrane.

I remember working with a guy with a commercial RO - his vendor had sold him a system magically configured for a 1:1 ratio with no knowledge of his water chemistry, and no warnings regarding proper pretreatment (softening) of his RO feedwater. This customer was going through membranes in about 2 weeks at the tune of $250 per pop. Within 5 minutes of starting to talk with him, and learning which vendor he had bought from, we diagnosed the problem and had it resolved.

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I have the 100gpd puratek unit pictured above. My unit came with the 450 restrictor installed. The box says this RODI setup will result in a 2.5:1 waste/product ratio. Which seems pretty close to what I get now.

OP said he replaced his 450 restrictor with a 800 restrictor. What does that do to the waste/product ratio?

Should I experiment with some different restrictors to see which works best? is there any calculator that will show what different size restrictors will do on different setups?

I do not have hard water, if that matters.
 
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I have the 100gpd puratek unit pictured above. My unit came with the 450 restrictor installed. The box says this RODI setup will result in a 2.5:1 waste/product ratio. Which seems pretty close to what I get now.

OP said he replaced his 450 restrictor with a 800 restrictor. What does that do to the waste/product ratio?

Should I experiment with some different restrictors to see which works best? is there any calculator that will show what different size restrictors will do on different setups?

I do not have hard water, if that matters.
I haven't measured my waste water but it does seem to visually be a bit more but not a huge noticeable difference. What I think is more important is my TDS post RO has dropped.
 

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I have the 100gpd puratek unit pictured above. My unit came with the 450 restrictor installed. The box says this RODI setup will result in a 2.5:1 waste/product ratio. Which seems pretty close to what I get now.

OP said he replaced his 450 restrictor with a 800 restrictor. What does that do to the waste/product ratio?

Should I experiment with some different restrictors to see which works best? is there any calculator that will show what different size restrictors will do on different setups?

I do not have hard water, if that matters.
what is your water hardness (in ppm or gpg)?
 

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Another note here... To determine the ratio of concentrate to permeate you have to MEASURE IT! I've been doing this for almost 25 years and I can't estimate it accurately by just looking at it.

 
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I have the 100gpd puratek unit pictured above. My unit came with the 450 restrictor installed. The box says this RODI setup will result in a 2.5:1 waste/product ratio. Which seems pretty close to what I get now.

OP said he replaced his 450 restrictor with a 800 restrictor. What does that do to the waste/product ratio?

Should I experiment with some different restrictors to see which works best? is there any calculator that will show what different size restrictors will do on different setups?

I do not have hard water, if that matters.

The ratio will go up. The 800 ml/min restrictor will allow more water out the waste side. I would expect something around 4:1.
 
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=110 ppm = 6.4 grains per gallon.
You said you didn't have hard water... but you do. Yours is in the category called "moderately hard."
Buckeye Hydro Hardness Categories.png
Interesting. I guess I never bothered to look up a chart before. Nobody around here has water softeners, so I just assumed our water was already considered on the softer side... our water report says our water total hardness has a range of 70 to 110.

I don't think I'm going to mess with my restrictor. I'm happy with how my unit runs for the most part. I get 0 tds out of the membrane in winter and 1 or 2 tds out during the summer months, uses very little DI, and waste water is 2.5:1, which isn't bad, so I'm happy.
If anything, I'm going to be adding a booster pump at some point as my pressure does dip below 60 psi occasionally. I think boosting my pressure to 80 all the time would benefit me the most.
 
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