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RO TDS Temporarily High When Float Valve Releases

Brandon

Active member
Messages
366
Location
Devon
Hi guys,

Got a bit of a problem with my RO that has actually gone on since I first bought it but now I run my RO straight through my DI and then into an IBC holding tank which I have installed a float valve on to cut off the RO supply when it's full.

The problem is that when the float valve disengages and the water supply turns back on again, the RO water comes out at really high TDS for about a minute and then slowly goes back down to normal (10 TDS) and then it's fine from then on until the float valve kicks in again.

This means that for about a minute when the water kicks in the RO is producing about 200+tds that progressively goes down but during that minute the high tds water goes straight through the DI and then into the tank therefore killing the resin much quicker compared to if it stayed at 10 tds.

It never used to be a problem as I used to fill the van tank with RO water and then polish it off on the go meaning I could just run the RO for a minute on the floor until the TDS went down and then fill up.

But now I've built a static system in my shed so I can fill the van with pure, but this problem means my 25 litre DI vessel has crept up to 2 TDS in a matter of months which should last a lot longer if the RO water always came out at 10.

What can be done to prevent this temporary high tds issue?

I do flush the system almost every time I use it for about 3 minutes. And I don't want the solution to be that I have to disconnect the RO from the DI EVERY time I want to fill up to wait for the tds to go down.

Any help would be greatly appreciated as it's starting to do my nut in!

 
Hi I have a system in the van with a ro and mine does the same
I run the first minute off through a hole in bottom of van and yes mine is about 200ppm


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Hi guys,

Got a bit of a problem with my RO that has actually gone on since I first bought it but now I run my RO straight through my DI and then into an IBC holding tank which I have installed a float valve on to cut off the RO supply when it's full.

The problem is that when the float valve disengages and the water supply turns back on again, the RO water comes out at really high TDS for about a minute and then slowly goes back down to normal (10 TDS) and then it's fine from then on until the float valve kicks in again.

This means that for about a minute when the water kicks in the RO is producing about 200+tds that progressively goes down but during that minute the high tds water goes straight through the DI and then into the tank therefore killing the resin much quicker compared to if it stayed at 10 tds.

It never used to be a problem as I used to fill the van tank with RO water and then polish it off on the go meaning I could just run the RO for a minute on the floor until the TDS went down and then fill up.

But now I've built a static system in my shed so I can fill the van with pure, but this problem means my 25 litre DI vessel has crept up to 2 TDS in a matter of months which should last a lot longer if the RO water always came out at 10.

What can be done to prevent this temporary high tds issue?

I do flush the system almost every time I use it for about 3 minutes. And I don't want the solution to be that I have to disconnect the RO from the DI EVERY time I want to fill up to wait for the tds to go down.

Any help would be greatly appreciated as it's starting to do my nut in!


Its called tds creep and every r/o does it.

The solution is the fit a 3 way valve so as to by pass the di vessel when the r/o first kicks in. If you are processing water into an ibc tank then some just send that first couple of minutes of pure directly to the IBC tank, then once the tds settles, redirect the water through the di vessel.




 
Last edited by a moderator:
13 minutes ago, spruce said:



Its called tds creep and every r/o does it.

The solution is the first a 3 way valve so as to by pass the di vessel when the r/o first kicks in. If you are processing water into an ibc tank then some just send that first couple of minutes of pure directly to the IBC tank, then once the tds settles, redirect the water through the di vessel.




Spruce you're an absolute legend.

Such a helpful video...it's one of those things where if you don't know...you don't know!

Thanks again mate.

 
Hi guys,

Got a bit of a problem with my RO that has actually gone on since I first bought it but now I run my RO straight through my DI and then into an IBC holding tank which I have installed a float valve on to cut off the RO supply when it's full.

The problem is that when the float valve disengages and the water supply turns back on again, the RO water comes out at really high TDS for about a minute and then slowly goes back down to normal (10 TDS) and then it's fine from then on until the float valve kicks in again.

This means that for about a minute when the water kicks in the RO is producing about 200+tds that progressively goes down but during that minute the high tds water goes straight through the DI and then into the tank therefore killing the resin much quicker compared to if it stayed at 10 tds.

It never used to be a problem as I used to fill the van tank with RO water and then polish it off on the go meaning I could just run the RO for a minute on the floor until the TDS went down and then fill up.

But now I've built a static system in my shed so I can fill the van with pure, but this problem means my 25 litre DI vessel has crept up to 2 TDS in a matter of months which should last a lot longer if the RO water always came out at 10.

What can be done to prevent this temporary high tds issue?

I do flush the system almost every time I use it for about 3 minutes. And I don't want the solution to be that I have to disconnect the RO from the DI EVERY time I want to fill up to wait for the tds to go down.

Any help would be greatly appreciated as it's starting to do my nut in!
I use a Y splitter for hozlelock fittings. All 3 female connectors have a flow valve to turn on and off to direct the water into or away from the d.i ?

 
??. That domino is to tilt the plastic box slightly to one side so the high TDS water runs that way.

As it fills up it runs to a half inch piece of hose that’s siliconed into the box that runs out to a waste pipe.

A northerner could never of thought of that ?

 
??. That domino is to tilt the plastic box slightly to one side so the high TDS water runs that way.

As it fills up it runs to a half inch piece of hose that’s siliconed into the box that runs out to a waste pipe.

A northerner could never of thought of that ?
Thanks for the pic. 

Just out of curiosity about the box and the siliconed hose...why not just run the high tds through a hose straight into the waste pipe? Why the hole in the box malarkey? ?

 
I'm sorry, but do you guys really turn valves on and off every single time you start to produce water? I know it's just routine to you at this point, but why not automate it? A timer board off eBay and a couple of solenoid valves could do it all automatically for you.

If tds creep is solved by flushing (doubtful?) it would be even easier to set up.

 
I'm sorry, but do you guys really turn valves on and off every single time you start to produce water? I know it's just routine to you at this point, but why not automate it? A timer board off eBay and a couple of solenoid valves could do it all automatically for you.
 
If tds creep is solved by flushing (doubtful?) it would be even easier to set up.
Enlighten us then Nudel. I rigged up a semi automated system - pretty much like you describe - but couldn’t build/design enough ‘failsafes’ in it to make it trouble free. I used cheap solenoids linked to my booster pump and flow meter but they kept failing and was a bit too scared of damaging my membrane for the sake of turning a lever for a couple of minutes so I could monitor it until the TDS was good enough to go to the DI


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I changed my output to John Guest fittings a few months back. Installed a splitter and put a shut off tap on either end. When the RO first starts up I close the valve to stop water going into the DI vessel and open the other one which goes out of the garage and dumps the water on the lawn. Once the TDS comes down enough I close open the valve leading to the DI vessel and close the other one. Not quite automated but easy enough to do.

IMG_9377.JPG

While we're on the subject of RO and I know our resident expert @spruce will read this... A few days ago i moved my tank, I have put fed the output pipe from the DI across the ceiling and it drops down into the tank. It doesn't seem to have caused any production issues but is there anything you can think of that may go wrong with that set up? I was concerned that perhaps the back pressure created from having to pump the water to ceiling height may send some back into the membrane and cause damage? Or am I just over thinking it?

 
Enlighten us then Nudel. I rigged up a semi automated system - pretty much like you describe - but couldn’t build/design enough ‘failsafes’ in it to make it trouble free. I used cheap solenoids linked to my booster pump and flow meter but they kept failing and was a bit too scared of damaging my membrane for the sake of turning a lever for a couple of minutes so I could monitor it until the TDS was good enough to go to the DI


The rough idea is:

Float valve activates booster pump and  a timer unit.

Timer unit relay is connected to two solenoids, one to NO and the other to NC.

One solenoid directs water to storage, the other one to drain.

Timer is set up to start at power on, opening the solenoid leading to drain for whatever minutes it takes to tds to fall. When the time is up the drain solenoid closes, automatically opening the one to storage.

That would work, no?

What I don't know is if the cheap smaller solenoids can handle the flow for larger ro systems.

 
The rough idea is:

Float valve activates booster pump and  a timer unit.

Timer unit relay is connected to two solenoids, one to NO and the other to NC.

One solenoid directs water to storage, the other one to drain.

Timer is set up to start at power on, opening the solenoid leading to drain for whatever minutes it takes to tds to fall. When the time is up the drain solenoid closes, automatically opening the one to storage.

That would work, no?

What I don't know is if the cheap smaller solenoids can handle the flow for larger ro systems.


IMG_2544.JPG

 
Theory is fine Nudel. You find the bits that will cope with it. The cheap solenoids are fine - as long as you have spares, it’s the timers I struggled with. Couldn’t find a 240v off the shelf version that you could adjust the time periods for more than a few seconds (10max). Looked at armadillo programming but my days of that stuff are long gone. It’s obviously possible as Gardiner’s sell one and x-line (sorry for swearing!) sell an auto-flush. Maybe a project for a cold winter night!!!


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