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RODI filters


BtmDweller

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I have a spectra-pure system I’ve been running for awhile. Running pre filter, carbon block, silicate buster, mixed bed DI resin. What’s the thoughts on running the silicate buster filter? What would run in its place? Also using a .5 micro pre-sediment filter, BRS sells 1 micro and 5 micron. Thoughts on difference from .5 to 1?

 

I’ve been super happy with my water. I’m guessing I may not need to use the silicate buster? They don’t last me long and kinda pricey. Currently using BRS replacement pack your own mixed bed DI resin final stage.

 

 

 

 

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I have their Maxcap and have just recently replaced the silica buster w/the even more expensive enduro.  It seems to be working great but in all honesty I was thinking of switching over to BRS media for my next refill.  In your case, I would have to say, if it aint broke, dont fix it.  
In my case, it's about the $.  There are threads out there proclaiming that the spectrapure filters last longer but I would be interested to see if that's actually true in my case.

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What is the micron rating of your prefilter.  If you are running a 0.5 micron pre-sediment filter then nothing smaller than 0.5 micron is getting to your sediment filter.  Would tend to clog the pre sediment filter and have your sediment filter not really doing much.  I run a 10 micron sediment filter, 5 micron carbon, 1 micron carbon.  Have never tried a silica filter

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With a 0.5 Micron carbon block you would be fine with the 1 Micron Prefilter, the prefilter will filter out solids down to 1 micron and then the carbon block will take out between 1 micron and 0.5 micron.  You could run a second carbon cartridge instead of the silica buster.  I've been using the AirWaterIce Typhoon III for years with their standard 10, 5, 1 filter array 

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Right when I say prefilter talking about the sediment filter. The .5 micron sediment takes a lot out and those are relatively cheap to replace. I’m thinking if they take a lot that’s a good thing saving the membrane and DI resins while initially stripping more solids out. BRS no longer sells .5 micron sediment filters, Specturepure still has them as the standard. Not sure how much a difference the .5 to 1 micron actually is though?

 

It is a money factor, as for the silicate buster. I can go through one in 3-4 weeks while making water $25-$27 each on top of other filter changes. Also was looking at bulk prefilters sold in 1 micron. I was thinking of using a single bed anion instead of silicate buster and then BRS purple mixed bed. If I’m not mistaken that will focus on phosphate and silicate removal. Am I better using two mixed beds though? Usually single beds would have one each cation and anion followed by mixed bed. Something to think about later, adding an additional stage.

 

Thanks for the input/discussion

 

 

 

 

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They last me a bit longer but yeah they are $$. You can ask spectrapure why you’re burning through them so quickly. I know there are cases where CO2 / cloramines can prematurely cause filters to die. They can trouble shoot. Spectrapure sells a co2 test kit I am about to use myself.

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If your water source treats with chloramines, adding another carbon block can increase contact time and help reduce the chance of RO membrane damage.

 

Spectrapure's SilicaBuster cartridge is another mixed-bed DI resin stage. As such, it has a fixed capacity for ion-trapping based on the resin type and volume. The more ions that you send into the stage, the more quickly it will be exhausted. There are several common scenarios that can result in quick exhaustion of your resin stages:

  • Damaged RO membrane or a membrane with a low rejection ratio
  • High TDS bursts due to a failure to flush the RO membrane before making water
  • High dissolved CO2 in water (more typically encountered in systems connected to wells)

A damaged RO membrane (or one with a low rejection ratio) will let more dissolved solids pass, leaving them to get picked up by the the DI stage. This will, of course, shorten resin life. Check the TDS in and out of your membrane (before the DI resin stage) after it's been running for a few minutes. If the TDS out of the membrane is any more than 3% of the TDS in, then you may have a bad membrane (or a poorly performing one) that needs to be replaced.

 

If you're running your RO/DI system in short bursts spread out over time (e.g. tying it directly to your top off or making just small batches of water) without flushing the membrane, then you're subjecting your DI stages to a lot bursts of high TDS water. You can test this by measuring the TDS of water samples directly from your RO stage (before it gets to the DI stage) right at the start of water production, and again at 1 and 5 minutes after start up. This burst can be as high as several hundred ppm TDS and last for a minute or more before dropping into single or low double digits. If you don't flush the membrane, the high TDS from these bursts will hit your resin stage and can shorten the life of any DI resin stage by a lot. The way to address this is to either make your water in larger batches less frequently or manually/automatically flush your membrane before and after each use (at the very least, before is recommended). My guess is that this is the main reason that your going through resin stages quickly.

 

Another reason for fast consumption of resin applies mostly to people on well water. If that well water is high in dissolved CO2, then it'll mostly make it past the RO membrane and then will be picked up by the DI stage as ionized carbonic acid. Addressing this problem can be a bit more complicated. I won't get into it here because I'm guessing that you're not on well water. (Some solutions involve degassing or aeration to blow off excess CO2.)

 

Other reasons such as temperature, pressure (provided you've not blown out your membrane), and poorly matched flow restrictors will have minor impact on membrane efficiency and should not be suspected in a situation like yours.

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Spectrapure sells the silicate buster as a means to catch the more difficult ions. If I remember correctly silicate is -4 charged. If the resin can only pull a fixed amount, could it actually pull more of the lower charged particles? I wonder if its realistically undetectable change compared with another mixed bed? Thinking of doing two BRS mixed beds instead.

 

I make 300+ when running 3-4 weeks almost 24/7. Rejection is high will need to test exactly. I’m assuming it’s not a membrane issue, and with the volume of water creating will eat up the resin.

 

 

 

 

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Spectrapure sells the silicate buster as a means to catch the more difficult ions. If I remember correctly silicate is -4 charged. If the resin can only pull a fixed amount, could it actually pull more of the lower charged particles? I wonder if its realistically undetectable change compared with another mixed bed? Thinking of doing two BRS mixed beds instead.

 

I make 300+ when running 3-4 weeks almost 24/7. Rejection is high will need to test exactly. I’m assuming it’s not a membrane issue, and with the volume of water creating will eat up the resin.

 

 

 

 

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Silica often complexes with other atoms. When complexes with oxygen, it forms a family known collectively as silicate (e.g. SiO4, SiO3, Si2O7, etc.). The charge varies. But, as you seem to recall, ortho silicate (SiO4) has a 4- charge.

 

As with any DI resin, the capacity is set NY the number of charge sites that ions can bind to. Thus, an ion with 4- charge will occupy 4x the sites required by an ion having a 1- charge. That's not where it ends, though. If an ion has higher affinity for a charge site than an ion more loosely bound there, the one with higher affinity may displace the lesser one,thereby releasing the lesser bound ion back into solution. If it's not captured further downstream in the resin bed, it emerges from the DI stage as TDS. This can result in a situation where water coming out of a depleted resin bed can actually be of lower quality than what enters as ions like phosphate are released in exchange for other ions of less concern.

 

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 Great, thanks for the input and great chemistry lesson!  Appreciate it.  I've switched over to the refillable BRS final stage mixed bed.  I'm going to see how it works changing out the silicate buster for two mixed beds 

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