RODI help

Jon Malkerson

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I’ve had this RODI unit for a long time and never had problems before today. I got all new filters for the unit and ran the housings through the dishwasher. I was able to fill a 55 gallon tank and 3/4 of the 120 with 0 TDS water. Soon as I seen 1 TDS I changed the DI filter. Now I have 2 TDS. The only thing I can think of is the RO membranes are from the LFS this time 2 75GPD and I was running membranes from HomeDepot witch didn’t say how many GPD. Before the filter change I was filling a five gallon bucket in about hour and a half with 2-4 TDS before DI. Now filling buckets just under an hour with 10-12 TDS before DI. Maybe I have the wrong flush valve or reassembled wrong? I just pulled the filters and checked the O-rings and gaskets.
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Ron Reefman

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I think that's serious water pressure. I have always felt normal city water pressure would run around 40 psi.

And with the old set up you only got 200 gallons of zero TDS before it went to 1 TDS? Is that what your 1st post said?
"I was able to fill a 55 gallon tank and 3/4 of the 120 with 0 TDS water. Soon as I seen 1 TDS I changed the DI filter."

My system starts at well over 300 TDS and my RO runs at 1 to 3 TDS for a couple of years. My DI holds zero TDS for a long time. I never measured it, but I'd guess it's at least a couple of thousand gallons. My system makes 30 to 40 gph at 120 psi, but my RO system is designed to run at that pressure. It's quite different than what 99.9% of reefers use. It came out of a coffee shop and it has 2 big RO membranes. But the DI is just a standard refillable DI cartridge and I measure with the same TDS meter as you.
 
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Jon Malkerson

Jon Malkerson

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If I could get a confirmation that I reassembled correct I’ll go get new membranes from Home Depot.
 

Ifreitas14

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The filters from the lfs might be cheaper so more things are getting threw it that’s why your seeing more tds before di
 
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Jon Malkerson

Jon Malkerson

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Before I changed the membranes I would get 2 TDS before DI. The only reason for changing them was I know they were three years old.
 
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Jon Malkerson

Jon Malkerson

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I think that's serious water pressure. I have always felt normal city water pressure would run around 40 psi.

And with the old set up you only got 200 gallons of zero TDS before it went to 1 TDS? Is that what your 1st post said?
"I was able to fill a 55 gallon tank and 3/4 of the 120 with 0 TDS water. Soon as I seen 1 TDS I changed the DI filter."

My system starts at well over 300 TDS and my RO runs at 1 to 3 TDS for a couple of years. My DI holds zero TDS for a long time. I never measured it, but I'd guess it's at least a couple of thousand gallons. My system makes 30 to 40 gph at 120 psi, but my RO system is designed to run at that pressure. It's quite different than what 99.9% of reefers use. It came out of a coffee shop and it has 2 big RO membranes. But the DI is just a standard refillable DI cartridge and I measure with the same TDS meter as you.
Yes I only made about 120 gallons of 0 TDS water with all new filters.
 
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Jon Malkerson

Jon Malkerson

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Well good thing my garbage man didn’t come yet. I just put the old membranes in and making good water now. I have always gone through DI pretty fast 200-250 gallons is that normal?
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Jon Malkerson

Jon Malkerson

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My original membranes were slightly different from each other. The two a got from LFS must be cheap. I do want to replace them who makes the best?
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piranhaman00

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I get 100 gallons or so from one DI Canister, I run 4 and fill them all when they run out with a bulk DI resin from amazon. Sucks but works. Old place I made 700 gallons of DI and never changed it, weird.
 

Shirak

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I buy my membranes from Water Anywhere. Lots to choose from GE AMI Dow WaterAnywhere

Personally I use an AMI highflow membrane. But I also have a custom system with 4" x 24" stainless canister for the membrane
 

Ron Reefman

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Buckeye Hydro is helpful and sells all kinds of membranes, even the crazy one's I use.

BTW, what is your TDS after the RO and before the DI?

I typically make 40 gallons at a time about every 2 weeks. That's a 1000 gallons a year and my DI lasts more than a year for sure... maybe 2 years!
 
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Jon Malkerson

Jon Malkerson

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Right now with the old membranes I have 4tds before DI. With the new membranes from LFS it was 10tds
 
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Jon Malkerson

Jon Malkerson

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huh.. those DOW membranes should give 97-99% rejection. Maybe one of the seals wasn't seated properly?
The first thing I tried was pulled the DOW membranes and they were a tighter fit than my originals then put them back in. No change
 

Shirak

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The old ones are generally easier to get in and out as the o rings have compressed a bit and such. Sorry no clue as to why they wouldn't be performing better.
 
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