RODI Experts Needed Please

[BaliReefBox]

Ok I am not sure where I have gone wrong but I would appreciate any and all help.
I recently setup a RODI system but its not going to plan.
What I have is
stage 1 5 um sediment filter
stage 2 1 um prefilter
stage 3 CTO
stage 4 CAG block
400gpd booster pump
stage 5 500gpd membrane with a 1200cc restrictor
well water in is 500TDS and water out of the ro is 20TDS. I hooked up RI cation and anion and the TDS went to 60 after testing with 1hr flushing. (20 in and 60TDS out) I disconnected the RI and got another membrane and run the 20TDS water into an drum(from the first membrane) then feed a new 100GPD RO membrane with an separate 200 GPS booster pump and an 800cc restrictor. RO out is 9TDS..

the RI resin I got was a repack so I really dont know the quality of it.
I am thinking of changing the 500gpd membrane to and 200gpd and the 100gpd to and 75gpd...
Any other input appreciated
FYI the top 2 filters are the RI and the are not connected in the pic

 

[shwareefer]

The DI resin going up even after an hour of flushing sounds like bad resin.

Your plan B sounds like something is wrong because 20ppm in should have resulted in 0 or 1ppm out not 9.

I'm not sure why you want to reduce your membrane sizes?

 

[BaliReefBox]

After watching countless videos on this the DI resin I got was the same color as the spent resin. From what I can tell it should be a dark bluish color fresh the golden straw spent..mine is the later.

 

[BaliReefBox]

well it turns out the resin I got is the correct color however I dont think it is quite the right one. I have ordered another type that shows it dragging TDS down from 94 to 12...
If I have 9 TDS prior to the RI how long can I expect it to last, I know this is how long is the next bus, but ball park 1000 litres or so?? It is a chinese copy of the MB400 purolite. BTW the next bus is 43'

 

[bshonesy]

So 9 TDS going in isn’t horrible, but I’m wondering why you need such a large system, even with well water? What is your pressure? And is the RO membrane a high quality one? Because 500 gpd would typically be quite pricey and normally something for more commercial/lab use. So I’m just wondering if this is a good 500 gpd membrane or something too good to be true? After all those questions I’ll give you the one tip I can think of now regardless of your answers which is you can try putting a needle valve (in place of your flow restrictor) on the rejection tube of your RO membrane and playing with it to see if you can get the TDS to go down coming out.

 

[BeanAnimal]

Being well water Maybe CO2
https://www.hamzasreef.com/Contents/Calculators/CO2DIDepletion.php
Also could be an issue with high silicates.

 

[Buckeye Hydro Verified Sponsor]

Let's back up a little and get your RO system configured correctly before we even consider your DI issues.

1. In the absence of any information about your feedwater, your recovery rate should be down around 20% - that would yield the proverbial 4:1 ratio people are familiar with. To get this ratio (assuming you have factory spec pressure and temperature) you'd need a flow restrictor somewhere around 5258 ml/min. You're using a 1200 ml/min flow restrictor so your current ratio of concentrate to permeate is less than a 1:1. If you have anything other than stellar feedwater you'll ruin your membrane in short order. You've probably already done that.

2. Next, once you get your membrane and flow restrictor configured to yield 20% recovery, your feedwater flow is near 2 gpm. Much too high for 10" x 2.5" carbon blocks and 1/4" tubing.

If you really need 500 gpd of permeate production:
start with a lab analysis of your feedwater, then
work with a knowledgeable vendor to install the correct feedwater treatment equipment, then
work with a knowledgeable vendor to install a light commercial RO system to fit your needs.

Russ

 

[BaliReefBox]

Ok firstly I would like to apologize for not replying sooner to the feedback/help I received in this thread. I have been away and super busy with getting the tank setup this rodi has kinda taken a back seat.

Progress so far is that I have taken the advise and installed a needle valve, reduced the size of the membrane to 100gpd and have rejigged the system layout.

Now I have 1:4 ratio of waste to product. (320ml to 1300ml) I downgraded my booster pump to 200gpd model and run 75psi across the membrane, inlet water px is 35 dropping to 15psi until the house pump kicks in and recharges the accumulator so cycling between these two px. current layout schematic is

05um filter
03um filter
01um filter
px gauge
carbon block
carbon block
booster pump
px gauge
membrane
di mixed MB400
di mixed MB400

Inlet TDS 550 and product out of membrane is 13TDS so this gives me about an 98% rejection rate. When I was running the 500gpd it was 96.5% rejection...I think my math is right. After the DI resin it is 0 TDS but the DI only lasted about 350ltrs before it started to creep up. I am not sure of the quality of the DI as it come "repacked" from sellers and is likely not as good as it could be. I have a bag of Aquaforest resin that I am saving for when I fill the new tank so will report back as to how that goes.

When I get more time I also have a 200gpd membrane that I will try out and see if I can get a decent result from it.

One question that I cant find the answer to is when the prefilters say 05um I am assuming that they are 5 micron filter and NOT 0.5 micron. Some of the sellers here sell the as half micron.

Any other advise thoughts on my current system to help improve it..
cheers