Converted Coralife RODI to 75gpd

[StirCrayzy]

I've had this unit since 2007 and bought because it was the cheapest RODI unit I could find at the time. I have good water pressure, and 110 ish TDS coming out of the faucet, and have never been dissapointed with the performance of this product. It has never failed to deliver 0 TDS output when maintained.
I don't think I've ever really had any failures other than a phantom drip from the bottom of one canister. It uses all of the standard 10" filter cartridges and bulk DI resin ( since buying the refillable cartridge) , and can accept higher rates membranes.
So, two circumstances collided to finally make a substantial change.
1. All filters are due for replacement. I do this once a year, for carbon and sediment, DI whenever it's needed, but I can't remember if I've ever changed the membrane itself... I know, should've scribbled it on the housing or something. I've also never flushed the membrane intentionally. At best I might have replaced this in 2011 ... ?
2. My tank is not in the greatest condition suddenly, and I'm checking things off the list of possibilities.

I'm not sure if this is the membrane that came with my PureFlo2 or if it's a replacement, but lists at 60 gpd which is close to what I have been producing , under 50 gpd.

Disassembled....


I ordered a full round of filters which arrived yesterday, including a DOW film-Tech 75 gpd membrane and flow restrictor from BRS.

After reassembly, the frustration began with getting 1:1 waste to product ratio. Then trying to find the flow restrictors...I now have 4:1 ratio.I'll test again Tonite, I'm not sure if I'm getting full production yet.
More to follow later...

 

[meknudson2]

I hope that it starts producing the way it needs to when you test it this evening.

 

[DaveK]

It looks like you did everything right by replacing the RO membrane with a larger flow rate one and also replacing the flow restrictor.

A flow of 4 gal of "waste" water to 1 gal of RO water is about right.

It's not a bad idea to add a bypass and valve around the flow restrictor, so you can flush the RO membrane from time to time.

 

[StirCrayzy]

It's a cluster of valves, and I don't have any spares right now because apparently my auto shutoff was holding back the waste ratio. And I used my valves as splices. I would like to make a simple flush valve eventually though.

After I removed the stock restrictors I removed the check valve going into the DI, Which didn't help. Then I removed the auto shutoff, and voila, 4:1 instead of 1:1 weird.

Previously the ratio was 2.5-3.0:1 with under 50gpd avg.
This evening so far I'm only getting 45 gpd ... The new setup has run for a total of 3 hrs so far, and if this rate doesn't pickup in another hour I'll measure product rate/ TDS , and try to re-seat the membrane.

 

[DaveK]

...
Previously the ratio was 2.5-3.0:1 with under 50gpd avg.
This evening so far I'm only getting 45 gpd ... The new setup has run for a total of 3 hrs so far, and if this rate doesn't pickup in another hour I'll measure product rate/ TDS , and try to re-seat the membrane.

Two things to keep in mind.

The quality of the RO membrane can have a lot to do with it. One that puts out water at under 1 ppm is filtering a lot finer than one that puts out 4 ppm. So you should test TDS before you worry about anything.

It's winter time and the source water is going to be a lot colder, so you'll get a lot less output out of an RO unit. I'd let it run about half a day before I tested TDS.

 

[StirCrayzy]

No change after reseating membrane.


And I've pulled all these little flange inserts from inside the lines. I'm pretty sure they are to expand the line to keep a seal inside the nut when tightened. No leaks without them on, so I'm not entirely sure, maybe they really are restrictors? And maybe there are more.



The only two things I found that were actual (no doubt) restrictors were on the waste line right at the fitting on the RO canister. ONE capillary type in the red line, and one in the threaded elbow . I can't imagine there are more anywhere else, I even unscrewed the elbows at the canisters to check internals.
Here is the current state of the tubing.



Ground water temp is 55℉, which is only 5-10 lower than avg summer temps. Maybe that does make a difference, but I don't believe substantially since I'm considering the setup is roughly 30% short of capacity.

Final Output is 0 TDS so I'm saving the 5 g that took nearly 3 hours to make.
I'll check TDS before DI tonight after another 5g run.

 

[SubRosa]

Unless you have two membranes, why do you need two flow restrictors? Did you forget to remove the old one?

 

[StirCrayzy]

Two were found in the original setup. I didn't expect that , and wonder if there are others Coralife is hiding somewhere.

I got a new 550 inline restrictor from BRS and that's all I intend to have running.

 

[SubRosa]

Two were found in the original setup. I didn't expect that , and wonder if there are others Coralife is hiding somewhere.

I got a new 550 inline restrictor from BRS and that's all I intend to have running.

That itself will likely increase your flow.

 

[StirCrayzy]

It's already been installed, and at the moment, the only known restrictor on the unit.
Today after running another 4 hrs, I'm still not seeing flow over 45 gpd. I'll keep researching and monitoring flow, but for now I'll be happy having quality over quantity. TDS Before DI is 002, after DI is 000, so I can't complain yet.
I'm open to suggestions if anyone is familiar with upgrading this unit, I must be missing something...

I'm most concerned that setting a timer for my standard 2.7 hr limit to fill my ATO reservoir will cause an overflow if it suddenly decided to start running 75gpd ...

 

[SubRosa]

Most units are rated at inlet pressure of 50-60psi and 70°F inlet temperature. Reducing either or both can seriously decrease production. If you need full production, a pre-heater for your inlet water is pretty easy to make.

 

[SubRosa]

My 100 gpd unit which fills a 55 gal drum overnight in the summer takes a day and then some to do the same in the winter.

 

[StirCrayzy]

Good to know, that's a pretty major difference.

Guess I was looking for an immediate difference in mine from one membrane to the other since the inlet temp didn't change in between the swap.

I really just like to be able to plan container fills.

 

[nanoreefing4fun]

if it helps... my 150 gpd in the winter temps under like outside ambient say... 45 or under it makes 5 gallons in about an hour, when warmer, like 70F or above I can get 5 gallons in 45 mins

 

[saintsreturn]

Wow, a lot of good info here!


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[StirCrayzy]

Turn of events, now I've only brewed 40 g or so up til last night. I filled my 20g container and checked TDS ... 025 ?
checked DI output was 006 , WTF?
I dumped the 20g from last night, rechecked all my connections purged the air from the DI canister, and checked again, still 005 ish? For comparison, I check one of 5g jugs I made last week, 000.
So what could've happened? All filters are brand new including resin... I'm going to run another 20g today, and see what it measures. If I need to WC at least it's better than 025.