RO plumbed straight to sump? Good or bad idea?

[Matt Peacock]

It's more of an ion issue inside the membrane, @spectrapure can explain it. The way I remember it, when the RO or RODI shuts off the ions that are normally stopped by the membrane can bleed through and upon startup it will be the job of the DI resin to remove it.

Correct.

If you do that multiple times a day, you'll prematurely deplete your DI, but if you can get that down to only a few times a week, then you wont have that TDS creep.

You'll still get TDS creep in the membrane (in fact it'll likely be slightly higher as it will have been sitting for longer), but on your example you'll only have to pay to deal with it once per week rather than multiple times per day. So orders of magnitude saving.

I seek to avoid this entirely by having an equal tee fitting just after the output of my RO membranes (i.e. just before the input to the DI cartridges). On the tee is a ball valve which drains to waste. Each time I start my RO/DO system, I open the ball valve so that the first few litres of output don't go through my resin. That initial high TDS output goes down the drain. Sometimes I'll check the TDS before closing the valve or sometimes I'll just wait a couple of minutes. Personally, I have found this one change saved me the most amount of money on resin. To be honest it's not just the money to me - I cannot stand changing resin so anything that reduces that I'm happy with.

 

[AZMSGT]

Correct.



You'll still get TDS creep in the membrane (in fact it'll likely be slightly higher as it will have been sitting for longer), but on your example you'll only have to pay to deal with it once per week rather than multiple times per day. So orders of magnitude saving.

I seek to avoid this entirely by having an equal tee fitting just after the output of my RO membranes (i.e. just before the input to the DI cartridges). On the tee is a ball valve which drains to waste. Each time I start my RO/DO system, I open the ball valve so that the first few litres of output don't go through my resin. That initial high TDS output goes down the drain. Sometimes I'll check the TDS before closing the valve or sometimes I'll just wait a couple of minutes. Personally, I have found this one change saved me the most amount of money on resin. To be honest it's not just the money to me - I cannot stand changing resin so anything that reduces that I'm happy with.

Yep, I purge my system for 4 minutes, take a reading if it’s zero, I close the purge line and start making water. IMHO, the purging is mandatory. There is always some TDS in the initial water out of the system.

 

[KHunter0622]

I am outside this box apparently.

System is a sediment filter, a carbon filter, two membranes with the waste of the first running into the second. Clean line from the membranes Y’d together and flowing into first one DI, then the next DI so the water is always flowing through a full nondepleted DI, Then there is a T one line to a 55 gallon drum with a generic float switch, the other straight to the sump with a valve, a float switch, and an optical switch. Every other dayish I open the valve and it fills the tanks evaporation. Before I go to bed or leave the house for an extended period I turn off the valve

Between the membranes and the DI I have a T then a one way that goes to a pressure reservoir with an in-line remineralizer that feeds my fridge/ice machine.

TDS to 55 gallon drum and tank is 0.
TDS to fridge minus the minerals is 6.
TDS going into the system is 180.

Every 4-6 months I replace an $18 tube of DI.

Eventually I am sure I will have 2 sediment filters and 2 carbon filters. Maybe a 3rd membrane. ‍

When the first DI depletes I take the second and move it to first, then put the new one in the second position.

It works for me. The wife loves the water from the fridge. The kids are safe from municipal water and drink more because it tastes great.

Someday I am going to get a 1” whole home and fill it with maifan stone as a type of prefilter for the whole house.

Cheers.

 

[vetteguy53081]

I am in the process of setting up a new rimless tank. As some of you are well aware of, evaporation rates on these are crazy.

My last tank was a Reefer 450 and I had the RO line go directly to my float switch with no issues. As far as my rookie self knew anyway.

Because the location of my knew tank, it would be tricky to run the RO tube from my 7 stage RO-DI set-up. New house has a slab for where as the old one had a crawl space to run lines where ever needed. At one time I had my 450 reef, a 350 predator tank and a biocube on a network.

With the new circumstance I was thinking of having a RO buddy 4 stage with DI just to feed tank evaporation. And just use larger kit for water changes and such.

Anyone have any experience or opinions with this type of setup?

TIA

Time and space saver and see no issue

 

[jsak1976]

I’ve had my RODI hooked directly to my tanks for over 15 years and have never had a problem, as long as you know what your doing it’s perfectly safe. My DI resin last 6 months and I use over 50 gallons a week. I use expansion tanks with pressure switch to keep it from cycling as much, optic sensors to open and close solenoid valves, back up float valve, and also a regulator so the pressure on the solenoid valve or back up float valve is less than 10 PSI. Now with Neptune Apex systems it makes it even safer because I can monitor how much water is going through the RODI line and limit it to a set value per day. My Apex would also alert me if the salinity changes anyways if for some reason it started pumping to much RODI water in.

 

[jhall2242]

Is there a way for an Apex to monitor pump on/off times for the RODI and the ATO pump? That would be a secondary alert.

 

[Roger D]

I don't have an ATO because I had a filter that plugged up and slowed the flow enough to bring on the rodi which drops the salinity.

 

[Dr. Dendrostein]

I am in the process of setting up a new rimless tank. As some of you are well aware of, evaporation rates on these are crazy.

My last tank was a Reefer 450 and I had the RO line go directly to my float switch with no issues. As far as my rookie self knew anyway.

Because the location of my knew tank, it would be tricky to run the RO tube from my 7 stage RO-DI set-up. New house has a slab for where as the old one had a crawl space to run lines where ever needed. At one time I had my 450 reef, a 350 predator tank and a biocube on a network.

With the new circumstance I was thinking of having a RO buddy 4 stage with DI just to feed tank evaporation. And just use larger kit for water changes and such.

Anyone have any experience or opinions with this type of setup?

TIA

If my setup, I'd install a solenoid shut off valve on 1/4" tube with sensor close to sump brim, in case of overflow.

 

[CavalierReef]

To be clear... just because one switches from constant cycling by hooking their RODI unit directly to their sump, to making large batches of RODI intermittently doesn‘t necessarily make TDS creep go away. The TDS creep is still there and you need to install a DI bypass valve (3 way valve) between the RO membrane and the DI stage to purge the system of TDS creep upon RODI system start up.

Exactly. BTW: Melvesreef (Marc) is also "in the business of selling RO/DI units and filters" and he recommends the protocol above every time you produce RO water to prevent TDS creep. Bleeding a few ounces of water every time will make your resin last a lot longer.

 

[Goo]

I am in the process of setting up a new rimless tank. As some of you are well aware of, evaporation rates on these are crazy.

My last tank was a Reefer 450 and I had the RO line go directly to my float switch with no issues. As far as my rookie self knew anyway.

Because the location of my knew tank, it would be tricky to run the RO tube from my 7 stage RO-DI set-up. New house has a slab for where as the old one had a crawl space to run lines where ever needed. At one time I had my 450 reef, a 350 predator tank and a biocube on a network.

With the new circumstance I was thinking of having a RO buddy 4 stage with DI just to feed tank evaporation. And just use larger kit for water changes and such.

Anyone have any experience or opinions with this type of setup?

TIA

I have mine plumbed straight to the sump with a float valve. i do have a shutoff at the source to turn on and off the float valve is just incase i forget to shut it off works great.

 

[jsak1976]

Is there a way for an Apex to monitor pump on/off times for the RODI and the ATO pump? That would be a secondary alert.

Yes there is

 

[rioreef]

Have mine direct to sump for fifteen years now. Never an issue. I have a double float switch from AutoTopOff.com. With the protective guards around the floats. Every few years I replace the solenoid. The switch is set on a timer that turns on every 8 hours for 15 min and runs for most of that time. So no constant on/off during the day

90gal with hood and glass covers

 

[SixtyFeetUnder]

Not recommended; it gives you less than ideal water quality. I used to have my old system plumbed that way. Your RO units efficiency is maximized when creating large quantities at a time; making small amounts at a time leads to TDS creep in your water.

Go to Avast marine’s website and check out their barrel tender product. He does a good job of explaining TDS creep and why plumbing a float valve directly to the sump is not ideal from a water quality perspective. I did it for ten plus years but won’t do it again.

 

[jhall2242]

Not recommended; it gives you less than ideal water quality. I used to have my old system plumbed that way. Your RO units efficiency is maximized when creating large quantities at a time; making small amounts at a time leads to TDS creep in your water.

Go to Avast marine’s website and check out their barrel tender product. He does a good job of explaining TDS creep and why plumbing a float valve directly to the sump is not ideal from a water quality perspective. I did it for ten plus years but won’t do it again.

Understood. I am setting up a new Apex. What I intend to do is have a low level sensor in my drum email me. I will then either remotely turn on the RODI or go down and do it manually so as to just run 50gal in a batch.

 

[savoyard]

As mentioned the constant starting and stopping the rodi would burn through di resin pretty fast. Plus the possibility of turning your salt tank into a freshwater tank is a real thing.

Thoughts on putting a solenoid on a timer between your prefilter and membrane to avoid the TDS creep? Then your making large batches.

 

[mfinn]

Thoughts on putting a solenoid on a timer between your prefilter and membrane to avoid the TDS creep? Then your making large batches.

I've found over the years when I start depending on mechanical devices, eventually they let me down.
I'm not sure how you would do it, but on my ro/di unit I have to flip the by-pass plastic valve and let it run for a few minutes until the tds goes down.
Then I turn it back.
You are right that you want to make large batches.

 

[stacksoner]

An unspoken truth and pain point of this hobby is that one's RO system will always find new, creative, and unthinkable ways to consistently flood your house.

While plumbing it directly to the tank sounds like an idea that will help streamline your maintenance routine, the quality and reliability of available equipment simply cannot be trusted to perform respective functions on a consistent basis without close monitoring.

 

[biecacka]

How much quicker does the on/off burn through the resin?


corey

 

[Sisterlimonpot]

How much quicker does the on/off burn through the resin?


corey

That's not an easy question to answer. The only way to put some perspective on it is to understand that upon startup of your rodi, the membrane isn't working at its intended capacity. There's a lot going on, but to keep it simple a lot of the TDS gets passed the membrane and it becomes the job of your DI resin (ation and cation) to attract those ions before it is dispensed into your tank or reservoir. By giving that job to the DI resin, it is depleted at a much faster rate.

The goal is to limit the amount of times your RODI unit cycles on. Take me for example, my RODI cycles on 3 times a week to fill up a reservoir, and I have to replace my DI every 6 months (on average). If I had my RODI cycle every time my tank called for top off (lets estimate 20 times a day) I would be replacing the DI resin almost on a monthly basis.

Of course there are a lot of other variables but for a properly installed RODI the number one killer of DI resin is constantly cycling the system.

 

[biecacka]

Yeah I have had his discussion with Russ at BuckeyeHydro and while he agrees it does burn them quicker, I was just wondering if anyone has done a direct Test to show the difference. my RODI is hooked up directLy to my ATO and it cycles on every few days believe. Partly because that is what my apartment space Allowed for. The bucket under the tank so instead of moving the RODI lines all the time, I just hard plumbed it. I have considered putting it in a nearby closet to allow me turn it on and off manually to save membranes.


corey