Hard working RO

[DBarsotti]

Hi there, I'm not on here as much as i should be but Rob has told me more than once that this is where i should be asking my questions... So here we go.

I recently set up a new propagation system, the total water volume is around 230g.. Between this and my 120g, I need around 70g a week of fresh water for water changes and top-off, depending on the time of year..

I decided it was finally time to buy and RO/DI unit as i've always bought my water and that just isn't practical anymore. I went with a 6 Stage RODI from Bulk Reef Supply.

After setting up the unit I found that pressure from my well is only about 40-45psi and I have a really high amount of iron or something in my water..


Here are some pictures of the system when i got it and then what it looked like after it produced about 230g of water..

the DI resin in these pictures is after already replacing 1 canister with new resin.



As you can see, the first canister is getting trashed and I am also burning through DI resin like crazy..











So as you can see, the water going into the DI is anywhere from 20-40 TDS and coming out at 0.

My question is.. 1. Is the rate these filters are being ruined normal or bad? and 2. Even with the TDS reading at 0 that doesn't mean that there still couldn't be harmful organics in the water, right? Is there a way to test for these? or further remove them or are they already being removed? I'm clueless when it comes to this stuff.

Even if I have to change all filters and resin every month, its still more affordable than buying water.. RODI water here runs for .50 per gallon.. So as you can imagine, that adds up fast..

oh and also.. My water source comes from a well and I'm running the water through my water softener prior to the RO but my water softener is old and more than likely needs to be replaced.. i'm working on that but haven't had the cash due to the holidays.. Ha, and this new prop system..


Thanks!

[AZDesertRat]

What you are seeing is somewhat common with domestic well systems.

Too bad you didn't post on here before buying a system as there are RO/DI systems better suited for domestic well systems that will give you a better service life and provide a much lower cost of ownership.

Oh well. lessons learned. There are things you can do to improve what you have but they will cost some money.
For starters you need a booster pump to get the pressure up in the 80+ psi range. This one step will improve your RO efficiency quiet a bit which will lengthen the life of the DI resin and pay for itself quickly. The best pump for your application is the Aquatec 8800. Make sure when you price it at the various vendors they include the 24v DC power supply and pressure switch. Many of them price things seperately so the original price looks attractive until you start adding the necessary components. You should be able to find it complete for around $125 which is not very many DI replacements which it will save you.

What is the tap water TDS from your well?
If you don't have a handheld TDS meter, which I recommend by the way, you can use your inline temporarily.
Remove the tee and probe on the OUT or treated water line and temporarily install it in the incoming or raw water line before the prefilter and grab a TDS reading.

You can get a pleated prefilter which gives you 10x the surface area and will last much longer before needing replacement. If its real bad there are washable type prefilters available too which never need replacing.

For DI resins since you have a dual DI take a look at the MaxCap and SilicaBuster DI resin combo from Spectrapure. I use it myself and my tap water TDS is over 650 and as high as 800 and I have only replaced the MaxCap cartridge once at 23 months of usage and the SilicaBuster is still the original from day one.
I have a 100G display with 30G sump and a 16G nano and cool strictly by fans and evaporation in Phoenix so go through quite a bit of water myself. I tried normal mixed bed bulk resin refills and could only get 150 gallons per 20 oz refill no matter how fresh the resin was or where I bought it and I tried them all in the last 15 years.

Have you tested the hardness coming from your softener? Water softeners do a great job of pretreatment for RO membranes, they love softened water.


Start with the booster pump, it should increase the RO efficiency at least a couple of percent which will double your DI life right off. Check your water softener, this too can increase the efficiency of the RO and extend the life of the membrane and filters. If you are still seeing fouling of the prefilter, try a lower micron pleated prefilter. The lower micron rating will also keep colloidal materials from getting to the carbon block and plugging it up causing a further pressure drop.

Chances are you have a CO2 issue too but lets attack this one piece at a time. CO2 is not an easy one but there are things you can do to help it later and it too will extend your DI life.

[DBarsotti]

Thanks for the reply, Rob was right, you are a very good source of imformation.

I will try and get a buster pump with my next supply order but in the mean time how frequently should i be changing my RO filters? Should i be worried about the water it is producing? I am a big sps head so Water quality is at the top of my list. I havent even used this water on my display system yet just for the fact I am worried about it having ill effects on livestock..

What RoDi unit would you have recommended instead of the one i got? Is there other pre-RO filters i could get?

I will try to get a reading on the TDS from my well this week and let you know.

I am also going to have someone come out and check out our water softner. and how would i go about doing a water hardness test? They sell test kits for this? (sorry i am clueless)



thanks

[jolson10450]

Thanks for the reply, Rob was right, you are a very good source of imformation.

I will try and get a buster pump with my next supply order but in the mean time how frequently should i be changing my RO filters? Should i be worried about the water it is producing? I am a big sps head so Water quality is at the top of my list. I havent even used this water on my display system yet just for the fact I am worried about it having ill effects on livestock..

What RoDi unit would you have recommended instead of the one i got? Is there other pre-RO filters i could get?

I will try to get a reading on the TDS from my well this week and let you know.

I am also going to have someone come out and check out our water softner. and how would i go about doing a water hardness test? They sell test kits for this? (sorry i am clueless)



thanks

i wouldnt be worried about the water it is producing if it is at zero, zero-4 is medical grade WFI which can be injected into a person it is so pure, think of it that way. as far as how often changing them, prefilters every 6 months, DI resin is usually the same but can last up to 1 year sometimes, and the membrane every 2 years.

there will not be any dissolved organics in the water because the RO membrane removes most of them and then the DI resin clings to the rest of them. the "tds" means total dissolved solids" so at zero... you have no total dissolved solids.

now to counter act what i am saying, did you calibrate the TDS meter before you used it? also did you calibrate using 2 solutions or one if you did calibrate it? be sure to calibrate it every 6 months with NaCl (sodium cloride) solutions with a known ppm to set it to.

like someone siad before its a common problem in well water to changes the filters so quick, what you can do is buy a stand alone filter or 2 and put 2 more prefilters on it before it enters your RO filters to try and cut the cost out some so it will go through 3-4 prefilters before hitting the RO rather than 1.

[creefer]

I have a similar problem with well water. However I installed a pre-filter ahead of the softener to take out sediment when I built the home 2.5 yrs ago. This helps the softener perform a bit better and I'm sure contributes to overall RODI performance. I need to heed AZ's recommendations as well and get a booster pump.

I have similar pressures as you and a really heavy iron content in my water. I chew up a pre-filter every 3 weeks however have not noted any iron staining anywhere. It is about that time that the water pressure in the home is notably reduced. The home that I demolished at this location had iron stains in the sinks and toilets from the heavy iron content.

I also plan on looking into the DI resin he recommends. Good luck and keep us posted.

[AZDesertRat]

You can buy a hardness test kit at Lowes, HD or Sears, they are very inexpensive and help you set your softener so it is doing it best job without wasting salt or allowing hard water to pass through.

As long as you are at 0 TDS or very close to it your system is functioning as it should. Prefilter andcarbon block changes are normally at 6 month intervals in most cases. If you have sediment. iron or particulate problems though I would go by pressure drop. I use two presure gauges on my personal RO/DI, the one that came on the membrane housing which is post prefilter and carbon and an additional one I installed before the prefilter so I can monitor pressure drop at a glance. If I start to see more than a couple psi difference between the two gauges its time to replace the filters. With the single gauge on the membrane housing I have no idea what my incoming pressure is so two gauges are good insurance.

I am not a fan or doubling up on filters such as two prefilters or two carbons, each thing you add in front of the membrane has an associated pressure drop which reduces the membrane efficiency. I would rather invest in better filters rather than more filters.

I use a 0.2 micron pleated prefilter and a single 0.5 micron 20,000 gallon Chlorine Guzzler type carbon block and after 23 months was still seeing only a 2 psi drop between incoming and post filters. Again thats with a tap water TDS between 650 and 800 but a low sediment or particulate loading.

Membranes normally go 18 months to 3 years but some people report over 10 years with Spectrapure systems. Randy Holmes Farley reported 10 years on a single membrane in a thread on RC a few years ago so it can be done. One reason this can be done is they use absolute rated prefilters in low 0.2 or 0.5 micron sizes versus others 1, 5 or even 10 micron nominal rated filters which are not as efficient. I believe www.buckeyefieldsupply.com also carries the pleated prefilters and 0.5 micron carbon blocks too. If its never reaches the membrane it does not have to be removed by it so the membrane lasts longer and functions better.

[creefer]

With only one DI canister, what resin would you recommend?

[TM01]

As a side note....

When first starting up a RODI or when adding new carbon block filters, dont forget to flush your carbon blocks out prior to plumbing in your DI resin.

[creefer]

As a side note....

When first starting up a RODI or when adding new carbon block filters, dont forget to flush your carbon blocks out prior to plumbing in your DI resin.

Good point! Carbon blocks are still good, I believe. My color changing DI resin is beginning to indicate that it's exhausted and I'm looking for options on the longest lasting, best performing options for the best dollar value.

[AZDesertRat]

You should replace the carbon every 6 months regardless of usage. This is done for several reasons, one is carbons pores begin to foul or plug leading to a presure drop at the membrane, another at least on municipal water is they remove the chlorine so chances of something groing in the housings is increased. Replacing them at 6 months and disinfecting the housings at that time reduce those odds.

A good mixed bed DI resin like Spectrapures SilicaBuster is a good choice for a single DI system. They claim it lasts 30% longer than other resins based on thousands of hours of testing and I believe it.
http://www.spectrapure.com/email/cus...reciation.html