350 PPM TDS before RO, 10 PPM after RO, 0 PPM after DI - chewing through resin

[KJAG]

No - it’s hooked up to a 20 gallon pressurized R/O storage tank (about 14 gallons stored).

How would I do that? Have clean go to one container and waste to another and measure amounts?

I’m using the resin that came with the unit from BRS.

I’ll have to look into that. I lease the office space so I doubt the land lord will put in a softener.

Sorry but what do you mean “pressurized?”

Two cups: run the unit and fill both with waste and DI. Four cups full, one cup DI is your goal.

I’ll try to find AZ’s response to my post awhile back. I forgot to mention him, which is disgraceful on my part since he made my life much easier. I owe that guy a couple hundred beers. Stand by.

 

[TinyChocobo]

Sorry but what do you mean “pressurized?”

iSpring 20 gallon tank with 14 gallon Storage Capacity Reserve Osmosis Water Storage Tank https://www.amazon.com/dp/B00439I86C/ref=cm_sw_r_cp_api_406HAbH54PZ8S

I have a 55 Gallon water barrel coming Tuesday I will be using with the RO float but for now this pressurized tank is what I have.

 

[Crabs McJones]

Can I run the membranes in parallel instead of in sequence?

Basically Sediment -> Carbon 1 -> Carbon 2 -> Y Fitting -> Check Valve on each -> Membrane on each -> Y Fitting -> DI

I think I would also need a Y to join the waste water outputs too for the restrictor.

Sounds like it's time for an experiment!

 

[Velcro]

I use city water and have high CO2 in the water. I have to degas after RO and before DI for a day or it kills my resin. I always see people say high CO2 only happens in well water, but that's really not the case at all.

 

[KJAG]

iSpring 20 gallon tank with 14 gallon Storage Capacity Reserve Osmosis Water Storage Tank https://www.amazon.com/dp/B00439I86C/ref=cm_sw_r_cp_api_406HAbH54PZ8S

I have a 55 Gallon water barrel coming Tuesday I will be using with the RO float but for now this pressurized tank is what I have.

Does it auto fill from the RODI unit once it depletes?
As in, the RODI autofills secondary to a float valve?

 

[TinyChocobo]

I use city water and have high CO2 in the water. I have to degas after RO and before DI for a day or it kills my resin. I always see people say high CO2 only happens in well water, but that's really not the case at all.

How would I test this? Beyond that how would I pass it through DI after the fact?

Does it auto fill from the RODI unit once it depletes?
As in, the RODI autofills secondary to a float valve?

It fills the tank and stops. It doesn’t run again until I drain the tank - which means it won’t run again until there is 14 gallons to make.

 

[Velcro]

How would I test this? Beyond that how would I pass it through DI after the fact?

CO2 test kits are pretty expensive if I remember correctly. I THINK there's a way to calculate dissolved CO2 concentration with a FRESHWATER alkalinity and pH test kit. Let's ask @Randy Holmes-Farley

 

[thetedinator]

So I could test disconnecting one of the membranes and run 75 GPD and see how much resin I use?

I was thinking running a larger restrictor (more waste water down the drain) would help offset the higher TDS?

Any reason I can’t go parallel instead of sequential for the membranes? A couple Y fittings and a couple check valves.

Parallel is the way to go. BRS even has a video about RO/DI systems where they concluded this.

I purchased this SpectraPure unit from Marine Depot in 2015.
I am very happy with this setup. High quality membranes are the key and this setup has two excellent membranes with 99% rejection. I use a SmartBuddie to automatically back flush the twin membranes every time I make water. I run my water pressure at 80-85. My tap water TDS ranges from 275 to 500 depending on the time of year. When the tap water is on the low range, I get RO output of 3. When the tap water is on the high range, I get RO output of 8-10. The SpectraSelect membranes are still producing low TDS water after 18 months of use.

Hope this helps.

 

[TinyChocobo]

Yeah I was thinking that with pH and Alk I should be able to approximate co2. That said I’m not sure on the math behind it.

I think if it is co2 I could just have the RO fill my barrel and use gravity to run the water through the DI on its way to my mixing barrel and throw an air stone in the RO tank or perhaps a pump pointed towards the surface of the water.

Is 10 ppm water enough to use up a lot of resin though? It may not be co2 and could just be the dual membrane and higher TDS output. If this is the case I could run a single membrane and deal with slower production as I will be storing a lot of ro/di in a 55 gallon drum so I will probably never be in a hurry.

I’m still wondering if I can run the membranes in parallel to get higher production without higher TDS output. It seems like running in parallel should eliminate the issue of higher TDS output as I would never be passing waste water through a membrane for a second time.

 

[KJAG]

How would I test this? Beyond that how would I pass it through DI after the fact?

It fills the tank and stops. It doesn’t run again until I drain the tank - which means it won’t run again until there is 14 gallons to make.

You would call your local municipal water source like I did. They can give you full specs of your water. I actually physically went down to mine because I was horrified at how fast I was exhausting DI. In the meantime, I’d google @AZDesertrat’s words on water softeners and rejection rates. From what I recall, if your TDS is approx 350, you may be alright with a 3:1 ratio. My personal experience: after softening my water prior to the unit, using Spectrapure cartridges and going to a 4:1 rejection rate, my problems were(are) completely solved.

 

[Velcro]

Yeah I was thinking that with pH and Alk I should be able to approximate co2. That said I’m not sure on the math behind it.

I think if it is co2 I could just have the RO fill my barrel and use gravity to run the water through the DI on its way to my mixing barrel and throw an air stone in the RO tank or perhaps a pump pointed towards the surface of the water.

Is 10 ppm water enough to use up a lot of resin though? It may not be co2 and could just be the dual membrane and higher TDS output. If this is the case I could run a single membrane and deal with slower production as I will be storing a lot of ro/di in a 55 gallon drum so I will probably never be in a hurry.

I’m still wondering if I can run the membranes in parallel to get higher production without higher TDS output. It seems like running in parallel should eliminate the issue of higher TDS output as I would never be passing waste water through a membrane for a second time.

Found this:

https://www.hamzasreef.com/Contents/Calculators/CO2DIDepletion.php

 

[TinyChocobo]

Parallel is the way to go. BRS even has a video about RO/DI systems where they concluded this.

I purchased this SpectraPure unit from Marine Depot in 2015.
I am very happy with this setup. High quality membranes are the key and this setup has two excellent membranes with 99% rejection. I use a SmartBuddie to automatically back flush the twin membranes every time I make water. I run my water pressure at 80-85. My tap water TDS ranges from 275 to 500 depending on the time of year. When the tap water is on the low range, I get RO output of 3. When the tap water is on the high range, I get RO output of 8-10. The SpectraSelect membranes are still producing low TDS water after 18 months of use.

Hope this helps.

Any ideas on how I would go parallel?

I can imagine a Y before the membranes and check valves to make sure water never goes the wrong way through a membrane.

I’m also thinking a check valve on each waste line before a Y and then the restrictor. Would I still want a 500 ml restrictor though for parallel?

 

[Velcro]

Yeah I was thinking that with pH and Alk I should be able to approximate co2. That said I’m not sure on the math behind it.

I think if it is co2 I could just have the RO fill my barrel and use gravity to run the water through the DI on its way to my mixing barrel and throw an air stone in the RO tank or perhaps a pump pointed towards the surface of the water.
Is 10 ppm water enough to use up a lot of resin though? It may not be co2 and could just be the dual membrane and higher TDS output. If this is the case I could run a single membrane and deal with slower production as I will be storing a lot of ro/di in a 55 gallon drum so I will probably never be in a hurry.

I’m still wondering if I can run the membranes in parallel to get higher production without higher TDS output. It seems like running in parallel should eliminate the issue of higher TDS output as I would never be passing waste water through a membrane for a second time.

I store my RO in a barrel above my RODI barrel and just gravity feed through the DI with it. I have an airstone in the bottom of the RO bucket. Works great.

 

[Velcro]

You would call your local municipal water source like I did. They can give you full specs of your water. I actually physically went down to mine because I was horrified at how fast I was exhausting DI. In the meantime, I’d google @AZDesertrat’s words on water softeners and rejection rates. From what I recall, if your TDS is approx 350, you may be alright with a 3:1 ratio. My personal experience: after softening my water prior to the unit, using Spectrapure cartridges and going to a 4:1 rejection rate, my problems were(are) completely solved.

I'm not sure they can tell you a whole lot about CO2 to be honest. I was under the impression that the CO2 is picked up after the water plant from the ground.

 

[TinyChocobo]

I store my RO in a barrel above my RODI barrel and just gravity feed through the DI with it. I have an airstone in the bottom of the RO bucket. Works great.

I’ll calculate my DI resin being used by co2 using that calculator after testing my tap water. Getting temp, alk, and ph should be fairly easy.

 

[TinyChocobo]

By my math I should get ~197 ml/minute clean water out of a 75 GPD membrane so for 4:1 I should be using an 800 ml/minute restrictor.

Two 75 GPD in parallel with a booster pump to keep pressure up should give me 400 ml/minute meaning I would need ~1600 ml/min restrictor.

Biggest auto restrictor available is 800/min so it looks like I would need a 400/min on each waste line before joining them.

This should double my production to 150/day but it won’t save on water - I will have the same 4:1 as I would with a single membrane I will just go through water twice as fast.

I’m going to order some parts and test this. I’ll need two 800/min auto restrictors, two Y’s.

I don’t think I will need any check valves as I don’t think there are any situations where it should back flow.

Worst case I drop to a single membrane with an 800/min to make sure I get 4:1 and I have an extra auto flush.

I’m open to advice and suggestions.

 

[TinyChocobo]

I also got a pair of ball valves so I can go from a dual parallel setup to a single membrane setup on the fly. I will need to turn down the booster pump if I do this but I keep the Allen wrench stuck to the pump.

 

[TinyChocobo]

Assuming both auto flushes are timed the same it should work well. What would be better is two regular restrictors - one in each waste line and then those lines connected together before and after the restrictors with a solenoid in between so both can be flushed simultaneously every time.

I wonder what will happen if one flushes with the other restricted. I think the one still restricted will drop pressure but won’t flush - not sure if there is a negative to this.

As the flush is only 15-25 seconds it shouldn’t be a big deal as even if they’re timed differently both membranes should still flush.

Another option is to join both lines together before the restrictors and to run a single auto flush and a single regular. This way when it auto flushes - it will flush both membranes. Yes - this will save some $$$ too.

 

[TinyChocobo]

This hopefully will help it make sense.

1. City water enters the booster pump
2. Water passes through sediment filter
3. Water passes through carbon block 1
4. Water passes through carbon block 2
5. Water split into two lines - each feeding a membrane.

RO filtered water output from membranes is joined back together into a single line and enters de-ionization and then RO/DI storage.

Waste water leaves each membrane and each goes to a different restrictor - one 800 ml/minute normal restrictor on one line and one 800 ml/minute auto flushing restrictor on the other line.

The waste lines are joined together before the restrictor pair so that when the auto flush happens both membranes get flushed through this line. When the auto flush is not flushing a combined 1600 ml/minute will be going down the drain.

Each membrane should in theory produce 200 ml/minute of filtered water before DI and 800 ml of waste water for a 1:4 ratio.

Booster pump should be able to push the pressure to make running this in parallel feasible.

I expect to have the parts needed to test this by Tuesday and will definitely update this thread.

If anybody has any suggestions or questions let me know. I don’t pretend to be an expert but I think I understand this well enough to experiment with this a bit.

 

[JMetaxas]

Imho. 300 gallons of water to exhaust a DI cartridge is pretty darn good.