How to flush RODI system?

[rja]

Hey all,
Recently I have been having issues with my BRS 4 stage reading like 25 TDS. I will make two 5 gallon buckets of RODI and the first reads 5 and the next reads 25. What gives?

Anyway, I cannot remember how I set up the system but I have only made 100~ gallons of water with this system.

How do I flush the system? I do not have a flush valve on the system already so I just ordered one from BRS. Do I just run the system for 10 minutes with the flush valve closed?

Should this help my system? When I first got it, I was at 0 TDS.

 

[John Bolden]

I believe you can back flush the ro stage but anyone here correct me if I'm wrong.

 

[rja]

I believe you can back flush the ro stage but anyone here correct me if I'm wrong.

how would I do that?

 

[rhitee93]

I can't help with back flushing as I haven't done that yet, but I just went through some first-timer ro/di issues that may be applicable tou your situation. In my case it looks like I have a lot of CO2 that was using up the DI bed quickly. Is yours changing color?

See my thread below:

https://www.reef2reef.com/threads/burning-through-di-resin-quickly.985152/

 

[CK00020]

Yes you can back flush it, I have an ro smart buddy and it does it for me. I always throw out like the first gallon anyway till the tds comes down

 

[John Bolden]

You basically rig it backwards

 

[rja]

You basically rig it backwards

so my inlet becomes my outlet and vice versa?

 

[zoomonster]

You bought a valve so that's all you need. Just install it on the waste line like pic.

 

[rja]

You bought a valve so that's all you need. Just install it on the waste line like pic.

Awesome, I was so confused about this whole system because it just looks like a jumbled mess of water lines but upon further inspection it’s pretty simple. If the flush valve only opens up the restrictor then can I not just remove the restrictor for 10 mins and reinstall it? I mean for $10 the valve saves any and all work so it’s totally worth it and it will be at my doorstep before I need to make more water.

Is the whole purpose of a flush just to send unrestricted water flow at a 100% discard rate through the RO membrane any dislodging and BS stuck in there? I always run my system for 30-45 minutes before capturing my water because that’s what I thought flushing was. But in this case, should I flush for 10 then go on capturing my water?

 

[zoomonster]

Awesome, I was so confused about this whole system because it just looks like a jumbled mess of water lines but upon further inspection it’s pretty simple. If the flush valve only opens up the restrictor then can I not just remove the restrictor for 10 mins and reinstall it? I mean for $10 the valve saves any and all work so it’s totally worth it and it will be at my doorstep before I need to make more water.

Is the whole purpose of a flush just to send unrestricted water flow at a 100% discard rate through the RO membrane any dislodging and BS stuck in there? I always run my system for 30-45 minutes before capturing my water because that’s what I thought flushing was. But in this case, should I flush for 10 then go on capturing my water?

Thats about it... just flushes the membranes. Time wise I just run it maybe 15m every so often.

 

[KStatefan]

I believe you can back flush the ro stage but anyone here correct me if I'm wrong.

so my inlet becomes my outlet and vice versa?

You will ruin the membrane doing that.

 

[rja]

You will ruin the membrane doing that.

yeah im not gonna do that lol

 

[EricR]

I have the BRS combo restrictor/flush valve and just run it open for about 5 minutes at the beginning and ending of my filtering run.

FWIW, on flush, mine still passes a little water through the RO membrane and DI chambers but not much.
I've wondered if this means that my flush valve isn't working 100% correctly or if this is just normal,,, but not enough to change it out (yet).

 

[homer1475]

Using the BRS "flush" valve will still create some product water, thats completely normal.

To prevent sending that high TDS water into your DI bed, you would also need a DI bypass.

 

[EricR]

Using the BRS "flush" valve will still create some product water, thats completely normal.

To prevent sending that high TDS water into your DI bed, you would also need a DI bypass.

Not looking at the plumbing right this second but I assume the water that still gets to the DI has already passed through the RO membrane so wouldn't be high TDS.
...or did you mean since it was going through the RO membrane at lower pressure the membrane wouldn't be filtering it as efficiently as normal (maybe)?

 

[rja]

I would think the water should only pass through the RO membrane. I remember when I was using an RO Buddie on a faucet without enough pressure and I wasn’t making any water so I don’t think it makes its way to DI bed.

Not looking at the plumbing right this second but I assume the water that still gets to the DI has already passed through the RO membrane so wouldn't be high TDS.
...or did you mean since it was going through the RO membrane at lower pressure the membrane wouldn't be filtering it as efficiently as normal (maybe)?

 

[homer1475]

Not looking at the plumbing right this second but I assume the water that still gets to the DI has already passed through the RO membrane so wouldn't be high TDS.
...or did you mean since it was going through the RO membrane at lower pressure the membrane wouldn't be filtering it as efficiently as normal (maybe)?

Low pressure, and your flushing the membrane = high TDS until it's flushed.

 

[EricR]

Low pressure, and your flushing the membrane = high TDS until it's flushed.

Thanks. Might think about putting a T-valve before the DI for full bypass but not too concerned.
It's a very tiny amount that gets through during flush cycle and my full batch of water at the end of each run still measures 0 TDS with a handheld meter.
*DI resin doesn't seem to deplete too quickly either which I guess would be the real concern

EDIT (now that I'm thinking about this) -- would ideal be:
1. A complete shut off valve before DI (to close while flushing) ...or
2. "T" with valve to still let water run (post RO) but direct away from DI (during flush)

 

[gabrieltackitt]

Thanks. Might think about putting a T-valve before the DI for full bypass but not too concerned.
It's a very tiny amount that gets through during flush cycle and my full batch of water at the end of each run still measures 0 TDS with a handheld meter.
*DI resin doesn't seem to deplete too quickly either which I guess would be the real concern

EDIT (now that I'm thinking about this) -- would ideal be:
1. A complete shut off valve before DI (to close while flushing) ...or
2. "T" with valve to still let water run (post RO) but direct away from DI (during flush)

Personally I do a combination of both options. Valve closed off on the DI + a tee and another short piece of tubing with a valve on it.

Often I will capture this waste product water and use it to water plants.

 

[ptrick21186]

I bought one of their T valves for my unit. Put one of my TDS meter leads on the line after the membrane and before the DI resin. When I first start it up the TDS creep can give me readings up to 70ppm sometimes. Once the TDS gets to the normal value of about 18ppm I open the T valve and let the water that was going to waste enter the DI resin. But if you REALLY wanna save money on resin I highly suggest upgrading to the 7 stage where you split the resin into anion and cation chambers. I've had mine up and running for about 5 months now and it's already paid for itself in DI resin purchases.

I also use this T-valve when I'm flushing my membrane so nothing is entering my DI chambers