RODI DI Resin beds, how many stages do you use? (1 Viewer)

[soymilk]

0 tds is 0 tds, but there are some things such as silica that is not a dissolved solid that can pass thru.

The slower rate gives the spectrepure “silica buster” more contact time since the silica resin is only like 1/3 to 1/2 of the total resin volume of that specific prefilled resin canister.

 

[jrounding]

I understand the contact time aspect of it, but the flow rates we are seeing is it really that significant? So let’s say you have dual 75 GPD membranes. That’s 6.25 GPH or .104 GPM theoretical max out of the membranes. Dual 100 GPD is 8.33 GPH or .139 GPM. The volume of an empty canister is ~.148 gallons. I’m not quite sure what volume the resin has or what it does to pressure drop across the cartridge so for ease of math let’s just use the empty volume. So the time to displace the volume with a dual 75 GPD is 1 minute 22 seconds. The time to displace the volume using dual 100 GPD membranes would be 1 minute 3 seconds. A difference of 19 seconds. So I guess the question becomes is the additional 19 seconds worth downgrading your membranes when it’s already contacting for over a minute?

 

[soymilk]

I think the comparison was single 75 gpd vs 200 gpd

3.125 gph vs 8.33 gph

 

[jrounding]

i think the comparison was single 75 gpd vs 200 gpd

3.125 gph vs 8.33 gph

I guess the question is how much contact time does the water need with the resin to do the ion exchange? So there’s a trade off. Flow rate to Resin contact time. At some point there’s no return on more contact time. So I guess it’s an individual thing. How much silica do you have and how much contact time is needed to bond those particles to the resin? If you don’t have much silica I wouldn’t want to reduce my flow rate so significantly, because it may be unreasonably limiting your water production for no real benefit.

 

[soymilk]

I feel like the whole silica thing is more of the moonshiners approach. In where you try to totally control as much trace minerals as you can. You effectively dose all minerals separately. So to do that effectively, you'd want to limit as much extra minerals and elements entering the tank. I don't know how much moonshiners reefing methodology applies outside moonshinin'.

It most definitely a personal call. Personally I don't use a ton of water unless im doing QT stuff. So I don't mind running at lower output. My 75gpd system is more water efficient and wastes less DI, so that helps too. If you're going though 40 gallons a week with top off and water changes. Does it matter if you have a 75 gpd system running for 12 hours vs a 200 gpd system for 5 hours. Its mostly running unattended.

I can see if you have to wheel out the RODI unit out every time. You'd want to make RODI water asap.

 

[foos]

/me sees people debating contact time to remove silica and is reminded to add todays silica drops to the tank

 

[jrounding]

I feel like the whole silica thing is more of the moonshiners approach. In where you try to totally control as much trace minerals as you can. You effectively dose all minerals separately. So to do that effectively, you'd want to limit as much extra minerals and elements entering the tank. I don't know how much moonshiners reefing methodology applies outside moonshinin'.

It most definitely a personal call. Personally I don't use a ton of water unless im doing QT stuff. So I don't mind running at lower output. My 75gpd system is more water efficient and wastes less DI, so that helps too. If you're going though 40 gallons a week with top off and water changes. Does it matter if you have a 75 gpd system running for 12 hours vs a 200 gpd system for 5 hours. Its mostly running unattended.

I can see if you have to wheel out the RODI unit out every time. You'd want to make RODI water asap.

For me I have limited space so I only have 3 or 4 gallons of storage. So I prefer to have a RO membrane that can recover fast and that’s why I use dual 100 GPD. Different environments and different needs.

 

[mitchell77546]

Is a 75 gpd membrane really his recommendation? Why? I’m sure the argument he has to make is more complex than what you presented but what you said makes as much sense as a square plug going through a round hole. 0tds is 0tds is 0tds.

I’m having “quality” of light argument flashbacks now where someone was saying there’s different “quality” of light. Photons are photons, and 0tds is can’

I don’t remember the entirety of his argument. I put all this extra beds in so I could see the color change and swap to prevent any breakthrough. Additionally the silica buster is expensive at $50 a cartridge so I fugure I may be protecting it to a degree. I’m sure that I’m not correct in this assumption. I’m not the most educated when it comes to water quality, but hell mixed DI resin is cheap enough… I really need to do an ATI test to see what my rodi look like. I’m just lazy and the tank is doing well enough.

 

[jrounding]

My tank looks like hell due to not being careful enough with my DI cartridge. That’s what prompted the upgrade to the triple DI system. I am getting a handle on it though with some water changes, scrubbing and waiting. Probably could get some more CUC as well.

 

[decimal]

Kinda in the same boat. Also making changes / upgrading RO to eliminate the possibility of make up water being the source for diatoms and all that. I do like the spectrapure possibility of a “roughing” stage for DI. Says it makes DI carts down the line last 3-4 times longer. So I’m thinking roughing, cation, anion and last stage mixed bed or silicabuster.

Anyone want to go in on a spectrapure order?

As far as dwell time, I would pose that as long as a minimum contact time is maintained, longer exposure won’t matter. The main component for measuring how long a DI cartridge will last is incoming TDS. As long as water passes through the DI media and effluent exits as 0 TDS water it is working. I guess I’m trying to say 0 TDS is 0 TDS. If feed water is going in @ 50ppm and out at 0 your cartridge will last x amount of time. If feed water is coming in at 180 TDS, the cartridge will exhaust that much faster with no change in flow rate.

OVERVIEW:

“The Mega-MaxCap DI Cartridge is SpectraPure’s newest addition to the MaxCap DI series of specialty deionization cartridges.
Like the legacy MaxCap cartridges, the new Mega MaxCap functions as a “roughing” DI stage, by removing the vast majority of residual ammonia, phosphates, and other trace ionized impurities that have passed through a purification system’s RO membrane. This pre-processing improves RO water chemistry to the degree that the downstream mixed bed and/or layered bed DI resins in subsequent “finishing” stages will continue to perform optimally for far greater durations, processing 4 times or more DI water by volume than otherwise possible.

The new Mega MaxCap DI’s higher capacity and enhanced phosphate removal provides even greater overall cartridge life, the Mega MaxCap processes even more water and extends the life of down-stream finishing DI cartridges even better than its predecessor. The Mega MaxCap DI should be used ahead of any indicating or non-indicating Mixed Bed, SilicaBuster, EnduroDI, or other conventional Mixed Bed DI “finishing” cartridges, to greatly extend cartridge life, thus requiring far fewer replacements over time. Enjoy consistently ultra-pure DI water, and water production cost savings.”

 

[BigRick]

Well I'm up to 600 gallons so far and everything is reading 0 TDS except Cation which starts out 14ppm then works down to 0. So I'm gonna put a T to flush that before it goes into Anion. Color changing DI/Silicone buster on last stage, the color has definitely changed but still reading 0. Weird thing its 3ppm put of the dual membranes before the Cation.

Also a while back we were talking about bacteria in the water supply if the rodi would take care of it... well on the news last night they said it will not rid the bacteria. So I'm thinking about doing a UV after the DI stage like SecondDecimal

 

[soymilk]

Kinda in the same boat. Also making changes / upgrading RO to eliminate the possibility of make up water being the source for diatoms and all that. I do like the spectrapure possibility of a “roughing” stage for DI. Says it makes DI carts down the line last 3-4 times longer. So I’m thinking roughing, cation, anion and last stage mixed bed or silicabuster.

Anyone want to go in on a spectrapure order?

As far as dwell time, I would pose that as long as a minimum contact time is maintained, longer exposure won’t matter. The main component for measuring how long a DI cartridge will last is incoming TDS. As long as water passes through the DI media and effluent exits as 0 TDS water it is working. I guess I’m trying to say 0 TDS is 0 TDS. If feed water is going in @ 50ppm and out at 0 your cartridge will last x amount of time. If feed water is coming in at 180 TDS, the cartridge will exhaust that much faster with no change in flow rate.

OVERVIEW:

“The Mega-MaxCap DI Cartridge is SpectraPure’s newest addition to the MaxCap DI series of specialty deionization cartridges.
Like the legacy MaxCap cartridges, the new Mega MaxCap functions as a “roughing” DI stage, by removing the vast majority of residual ammonia, phosphates, and other trace ionized impurities that have passed through a purification system’s RO membrane. This pre-processing improves RO water chemistry to the degree that the downstream mixed bed and/or layered bed DI resins in subsequent “finishing” stages will continue to perform optimally for far greater durations, processing 4 times or more DI water by volume than otherwise possible.

The new Mega MaxCap DI’s higher capacity and enhanced phosphate removal provides even greater overall cartridge life, the Mega MaxCap processes even more water and extends the life of down-stream finishing DI cartridges even better than its predecessor. The Mega MaxCap DI should be used ahead of any indicating or non-indicating Mixed Bed, SilicaBuster, EnduroDI, or other conventional Mixed Bed DI “finishing” cartridges, to greatly extend cartridge life, thus requiring far fewer replacements over time. Enjoy consistently ultra-pure DI water, and water production cost savings.”

Tds doesn’t measure silica

So the slower dwell time was to make sure the spectrapure resin for silica has the most contact time as possible.

I’m doing cation, anion, mixed bed, silica buster like rick. Bill anion is cheaper to buy than silica busters.


My tds outta the ro is 4-5. Then 11 out of cation. Then 0 from anion.

 

[decimal]

Right. So if you attached a higher volume membrane with output of the same tds value, your cation and anion tds values would remain the same. Not affected by dwell time or flow increase / reduction. Silica, as well as all charged ions, are captured by the electron charge of the resin as it passes through the DI media. We would we rely on tds as a bellwether gauge meaning that if tds rises above 0 your DI media charge (+\-) has been depleted and silica absorption, along with all other charges ions, has ceased.

Imho, dwell time is a negligent factor.

Edit: I feel further clarification is needed. We are talking about absorbing polarized ions of positive (+ cation) or negative (- anion) charges.

Charged ion impurities are removed in the DeIonization process creating pure water. But since we are talking about exchanging charged ions, that exchange process occurs at a set rate of how fast an electron can attach itself to another electron. Contact time is of negligent concern. If dwell time was a factor, a slower flow rate would result in a faster media exhaustion rate yet we know the opposite, a slower flow rate results in an increased media lifespan since the ionic impurities are filtered out more slowly.

 

[BigRick]

My tds outta the ro is 4-5. Then 11 out of cation. Then 0 from anion.

Okay that makes me feel better

 

[mittens]

My latest Spectrapure color indicating didn’t color indicate so I don’t even bother with color indicating. I buy sediment and carbon from brs, but DI from Spectrapure. Their cartridges are more expensive but they do last a lot longer and make my life easier since I hate flushing filters. I don’t have a 10 stage anymore and only have 3 DI canisters so I have to prioritize which DI I want. All I care about is basic zero tds, which a
mega max high capacity followed by an enduro satisfies.