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Fatman 
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 Topic: RO Filters
Posted: March 14 2014 at 11:36pm |
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I bought a SpectraPure RO/DI unit a couple of years ago and ran it for over a year on the factory filters. I needed to change them so I bought some from the LFS. These have lasted about 2 months. With the factory filters I had about 7 TDS through the RO and 0 through the DI resin. With the locally purchased filters I get about 25 through the RO side and 5 through the DI resin. Tested tonight and I'm getting 14 out of the DI resin side. I have added an ice maker that uses water out of the RO side so I'm going through filters like crazy.
Where is everyone getting filters lately? I read that a .5 micron carbon filter should be good for up to 10,000 gallons, but I'm not getting near that. Need a couple of good filters (sediment and carbon) at a reasonable price without getting my throat cut on shipping. I'm also considering adding another sediment filter so I'll have two of them in line before it goes to the carbon. What micron should I be running for good economical filtration?
Anybody have any favorite place to get them?
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Mike Savage
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Posted: March 15 2014 at 7:40am |
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I've always gotten my filters from Bulk Reef Supply. Sorry I don't know the answers to the rest of the questions.
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LaRue
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Posted: March 15 2014 at 8:06am |
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I get mine from brs and I use a 1 micron sediment filter instead of the 5 micron filter that brs sends with there units they are less than five bucks from brs so I order a bunch and change them out pretty frequently to help extend the life of the more expensive filters.
Edited by LaRue - March 15 2014 at 8:59am
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Mark Peterson
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Posted: March 15 2014 at 8:38am |
Those kind of TDS numbers would indicate that a Membrane change is in order. Membranes that go bad do so relatively quickly in a month or two. They run for years at the usual 0-5 ppm then "suddenly" creep up to +20 ppm over the course of a month or two. Regarding pre-filters, Home Depot or Lowes filters in 2-packs are about the same price as BRS, but with Amazon Prime I can get a 4-pack for even less cost/filter and free shipping to boot! I  Amazon Prime. I believe a 5 micron ahead of a 1 micron sediment filter will extend the life of the 1 micron and extend the time between filter changes, maybe even doubling the interval between changes. It will not change the life of the Carbon filter, but a so-called Block Carbon filter will last a lot longer. I opened a used block carbon filter the other day to see how it's made. It's basically a big roll of AC impregnated paper. The block carbon filter is noticeably heavier but I'm not certain how much of that weight is due to additional carbon. I've been wondering if an RO canister, filled or partially filled with the same AC we use for our tanks would work as well or better. If it works, thinking of the amount of AC in these filters, I'm pretty certain it would be less cost. It would be just like the Carbon Reactor many use in their tanks. Nikki, our resident Engineer probably has some good comments about this... Aloha, Mark 
Edited by Mark Peterson - March 15 2014 at 9:01am
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Fatman
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Posted: March 15 2014 at 8:47am |
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Mark, I looked at Amazon and am having a hard time finding a good price on the carbon filters. Most that I'm seeing are 5 micron. The one's that came with my RO unit are 1 micron. Which one's are you getting?
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Mark Peterson
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Posted: March 15 2014 at 9:07am |
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Reefkeeping Tips, & quick, easy setup tricks:www.utahreefs.com/forum/forum_posts.asp?TID=9244 Pay it forward - become a paid WMAS member
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Mark Peterson
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Posted: March 15 2014 at 11:31am |
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ReefdUp
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Posted: March 15 2014 at 12:02pm |
 Mark Peterson wrote:
Nikki, our resident Engineer probably has some good comments about this... |
Radar engineers probably don't know much about water purification...  That being said, I attended a class taught by Buckeye Field Supply (water purification company in the midwest) about 7 years ago. They had studied the pros/cons of various systems, and the best "bang for the buck" for *most* hobbyists was a 5um sediment, 5um carbon, 75gpd membrane, and DI chamber. Of course, there are benefits of multiple sediment filters, etc., but economically speaking for most people, that was not the case. To get to the root of the problem, measure the TDS of your tap water, after the RO membrane, and after the DI. Also, what's your pressure reading before the membrane? What ratio of good water to waste are you getting? Your dissolved solids should decrease very little from the tap water until the membrane. The membrane is the real workhorse in the system. There isn't much point in adding another sediment filter (for most people) when the membrane is the workhorse. Going to a 1um sediment with 0.5um carbon filter just means they'll clog faster and waste money (a 75gpd membrane is only $25-30 replaced every year or two...but a single carbon filter is $10+ replaced every 6 months or so.) Personally, I like the variable-depth sediment filters (they start at 5um on the outside and decrease to 1um on the inside.) But, they're more expensive (and sometimes hard to find), so I just use 5um. Carbon blocks should last *much* longer than the sediment filter, but most people change them with the sediment filter. Anyway, RO/DI system requirements can vary greatly from setup to setup, so the questions above should help guide you in the right direction.
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www.reefdup.com
Diving since 2009, reefkeeping since 2007, & fishkeeping since 1987
200g, 75g, & 15g Systems
PADI Advanced Open Water
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ReefdUp
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Posted: March 15 2014 at 12:23pm |
Fatman wrote:
With the factory filters I had about 7 TDS through the RO and 0 through the DI resin. With the locally purchased filters I get about 25 through the RO side and 5 through the DI resin. Tested tonight and I'm getting 14 out of the DI resin side. |
So, let's say your tap water TDS is 300 (about where mine is, but I think you have a slightly lower TDS since you're up the hill). If you're using a 75gpd membrane (I think you are...has a rejection rate of 98%), your TDS after the membrane should be about 6 (which matches what your factory filters pretty much.) If your membrane was still good and you're getting 25 TDS out of the membrane, then your tap water is upwards of 1250. That doesn't make sense (even if they are flushing the lines). So, your membrane is most likely bad. This will make your DI resin go bad quickly. Also, keep in mind that the recharged DI resin I gave you will go bad slightly faster than brand new resin. It shouldn't be very noticeable though. I'd change your membrane (and all the other filters out for good measure too). Don't forget to pre-rinse your carbon block before installation.
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www.reefdup.com
Diving since 2009, reefkeeping since 2007, & fishkeeping since 1987
200g, 75g, & 15g Systems
PADI Advanced Open Water
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wickedsnowman
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Posted: March 15 2014 at 12:48pm |
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I have always bought my filters from purewaterclub. They are super inexpensive IME last just as long as brs ones and usually have free shipping. I just stock up with a bunch then start changing them whenever my tds starts showing.
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