trmiv
Well-Known Member
OK I need some help on my RO/DI unit. First some background.
Last month I purchased a Spectrapure chloramine RO/DI unit. I set it on the counter and hooked it up temporarily and ran over 2 hours of water through the membrane and down the drain (bypassing the DI). Then I moved it under the counter and got it hooked up the way I wanted it. Unfortunately when I did that I didn't realize I had the shut off valve on the waste line shut off. With it shut off I ran a few hours of water through it. After realizing my mistake I opened the drain. I let it run for a few hours more and the TDS coming out of the membrane was at around 30 at that point. Slowly over a few hours it decreased to around 9-10. Still with an input TDS of 120 thats only about 91% rejection. I ran it for a few days filling my 120g, and the rate never decreased. I contacted Spectrapure and they speculated that having the waste accidentally plugged may have damaged the membrane so they offered to sell me a new membrane at half price, which I took them up on.
I received the new membrane yesterday afternoon. I put it in the unit, and ran about 5 hours worth of water through it. The TDS out of the membrane started around 50 TDS, and has declined to 30, but it didn't go any lower. Today I've had the unit running for about 8-9 hours trying to get the TDS to decline, and it dropped to around 20 after a few hours, but refuses to budge from there. I've taken the membrane out multiple times and reseated it. Lubed the o-rings to make sure they are sealed. I've also tried a different membrane housing that I had. Nothing has made a difference. I tested the waste water and I'm not seeing any breakthrough of ammonia, so I believe the prefilters are still working fine.
I'm using a booster pump at 60psi at the membrane. Water is really warm this time of year, in the low to mid 80's out of the tap. Current ratio of waste to product is about 3.37:1. I'm testing the TDS with two brand new in-line TDS meters that read the same on 3 different points. Also I have a handheld unit that I calibrated, and I'm measuring that by running the water into a cleaned glass container that I let the water overflow the sides as I measure. So I'm pretty confident that my measurements are close to correct.
At this point I'm confused. These are pretty simple units. I've checked and re-checked everything and it appears to be setup correctly. I don't understand why I can't get anywhere near a decent rejection rate. I can stick the original damaged membrane back in and get around 9, but even that isn't great. I expected a new membrane to at least get me to 96%, which would be around 5. Ideally I'd be closer to 98%. I filled my 120 with the previous membrane with an old set of DI resin I had, but that's exhausted and I don't want to waste the new resin. In the meantime I'm just dumping the water down the drain, so this is a ton of waste.
I plan to call Spectrapure tomorrow, but I wanted to see if anyone had any ideas that I'm not thinking of.
Last month I purchased a Spectrapure chloramine RO/DI unit. I set it on the counter and hooked it up temporarily and ran over 2 hours of water through the membrane and down the drain (bypassing the DI). Then I moved it under the counter and got it hooked up the way I wanted it. Unfortunately when I did that I didn't realize I had the shut off valve on the waste line shut off. With it shut off I ran a few hours of water through it. After realizing my mistake I opened the drain. I let it run for a few hours more and the TDS coming out of the membrane was at around 30 at that point. Slowly over a few hours it decreased to around 9-10. Still with an input TDS of 120 thats only about 91% rejection. I ran it for a few days filling my 120g, and the rate never decreased. I contacted Spectrapure and they speculated that having the waste accidentally plugged may have damaged the membrane so they offered to sell me a new membrane at half price, which I took them up on.
I received the new membrane yesterday afternoon. I put it in the unit, and ran about 5 hours worth of water through it. The TDS out of the membrane started around 50 TDS, and has declined to 30, but it didn't go any lower. Today I've had the unit running for about 8-9 hours trying to get the TDS to decline, and it dropped to around 20 after a few hours, but refuses to budge from there. I've taken the membrane out multiple times and reseated it. Lubed the o-rings to make sure they are sealed. I've also tried a different membrane housing that I had. Nothing has made a difference. I tested the waste water and I'm not seeing any breakthrough of ammonia, so I believe the prefilters are still working fine.
I'm using a booster pump at 60psi at the membrane. Water is really warm this time of year, in the low to mid 80's out of the tap. Current ratio of waste to product is about 3.37:1. I'm testing the TDS with two brand new in-line TDS meters that read the same on 3 different points. Also I have a handheld unit that I calibrated, and I'm measuring that by running the water into a cleaned glass container that I let the water overflow the sides as I measure. So I'm pretty confident that my measurements are close to correct.
At this point I'm confused. These are pretty simple units. I've checked and re-checked everything and it appears to be setup correctly. I don't understand why I can't get anywhere near a decent rejection rate. I can stick the original damaged membrane back in and get around 9, but even that isn't great. I expected a new membrane to at least get me to 96%, which would be around 5. Ideally I'd be closer to 98%. I filled my 120 with the previous membrane with an old set of DI resin I had, but that's exhausted and I don't want to waste the new resin. In the meantime I'm just dumping the water down the drain, so this is a ton of waste.
I plan to call Spectrapure tomorrow, but I wanted to see if anyone had any ideas that I'm not thinking of.
