Filter pair for water softener setup?

[Brian]

Hi. A year ago we had a new twin-resin-tank water softener installed. Water is VERY hard without it. At the time, I insisted they put in a pair of POE filters with it - a sediment and carbon filter. But I was too busy to discuss options with them. What we got appears to be (no markings) two standard 3/4" Pentek/Amatek housings that are black with red PR buttons, and clear screw-on cannisters for the 10" x 2.5" filters. The string filter filter fills with "orange jello", and the white smooth poly-wrapped carbon filter plugs with fine rust sediment.

We also already have the excellently-rated e-Spring UV/carbon electronic filter under cabinet. One reason I insisted on the filters was because sediment plugged up the previous resin bed, and another is because this $120 UV filter would previously plug up with rust sediment in 4 months instead of lasting a year. With the POE filter arrangement I've managed to get it to last a year by rinsing the filter off every couple of months when the water slows to a .25 gpm trickle.

The current POE filters are a string-wound polypro sediment rated 5 microns (at $5, or 10 micron for $3 depending on purchase), which lasts about 4 weeks in our 4-person family, and a multi-purpose carbon filter that is a non-label bulk purchase item from our local drinking-water distributor. This carbon filter lasts about 8 weeks, and by 10 weeks the pressure-drop is so high that max flow drops into the 1.5-3.0 gpm range. We're told that in other areas this carbon filter lasts 4-6 months when a sediment pre-filter is used. The filter price started out at about $14, went to $16, and last week I was informed that it's now $25. They tried to switch to a different filter several months ago, a KX Matrikx Pb1 model 06-250-125-975, but got a lot of complaints: in our subdivision it would last us no more than 2 days before flow dropped below 1 gpm.

My sense is that after looking over the local retailers, they've decided they have a captive customer market and can freely gouge us. Time to find another filter & supplier.

I'm looking for economical sediment reduction to make sure my $120 drinking filter lasts a year, and prefer some carbon to knock down the chlorine/chemical levels. So with that history, I've got a two questions:

1) Assuming I don't change filter housings, what combination would you recommend?
2) If I re-do the PVC piping arrangement, it would be easy to install a pair of 20" filter housings (want see-through, prefer same diameter for broader filter options & pricing, but could go larger dia.), and if I bought additional brackets, I could even use one or two of the current filter housings as pre/post/intermediate filters. Given this second scenario, but the same target goals, what would you recommend?

[Gary Slusser]

You mention the softener to say you have one but never mention it again. It will remove the ferrous iron and hardness from the water which is very important for the UV to work correctly. But how is it working now, especially with these very small particulate prefilters that are severely reducing the water flow and pressure to it? The reduction is to the extent that you may be ruining the resin because of improper backwashes.

What brand control valve is on the softener. If it is a Fleck, you don't need a prefilter.

I am not a fan of prefilters for a softener, or removing chlorine on a POE basis. You can cause problems for a softener and create a bacteria problem in it and the rest of your plumbing. I suggest shower head filters and a drinking water filter at the sink instead of POE carbon filtration. Carbon block types are not a viable choice, as you see, they block up very quickly at POE flow rates. BTW, his price is average for the cartridge you got and you can't do better than Kx.

If you have a clear to reddish orange brown snotty slimy substance in the sediment filter, that indicates IRB (iron reducing bacteria), a large group of harmless anaerobic and aerobic nuisance bacteria. It can colonize a softener and plumbing and cause an odor problem like H2S (sulfur/rotten egg). That is much more likely to harm the RO than 'sediment'.

A softener is a fairly good sediment filter, although we don't want to use a softener as a filter, proper backwashes remove the 'sediment' trapped by a softener. To do that the softener needs all the water flow and pressure it can get; prefilters reduce both. Rotary disk type control valves may need a prefilter, but Autotrol, Clack and Fleck control valves do not.

You should have pressure gauges before and after each of your filter housings and change the cartridges when your peak demand flow causes a pressure loss of 15 psi across the filter. That's regardless of how old the cartridge is, or what type it is or how much it costs. And unless you have a pleated paper type cartridge, washing them doesn't 'clean' them.

[Brian]

Clarifications

Gary - Thank you very much for the input. I'll try to clarify things and answer your questions. Years ago I did plumbing design engineering, which I enjoyed a lot, but this home purchase 5 years ago is the first I've owned with POE water filtration, and also the first water-softener scenario I've been exposed to.

Sorry to imply that our water flow is normally slow - it's not. I was trying to illustrate that because we have such hard water with so much precipitated solids due to the Chlorine & other added chemicals, the filter life isn't that great and the drop-off in flow rate proves the point. In finding out how long the filters last, and forgetting to buy another filter once or twice, I've made those discoveries on water flow & pressure drop. The reason the KX would only last 1-2 days is because it is a 0.5 micron filter: way too much stuff was passing through the 5 micron sediment filter (Purwater SW05-S, string-wound polypro) to allow the KX to last. I suspect that particular KX is great for pretty clean water POE, or under-counter POU, but that doesn't describe my situation. If I wanted to use that KX filter, I'm guessing I would probably need to feed it through a 1-micron sediment filter in at least a 20" size?

The control valve assembly is the Culligan Soft-Minder Twin Automatic control. The backwash is rated at 2.0 gpm according to the label, and under most (not all) circumstances I don't think there's an issue with it getting adequate flow. If any pics would help, let me know.

I may have mis-spoken on the failure mode of the previous water softener. I was told that it had plugged up, and was causing the two-time overflow of the brine tank (that screwed up flooring and a couple of walls because there is no floor drain in the utility room). However, I have no first-hand knowledge of it and did not examine the old unit when it was removed. As I mentioned, very busy at work at the time.

Your description of IRB sounds like what I observe, but I see it only in the sediment filter, which is the first thing that the water hits at POE. Our subdivision is noted for very high iron content, so I suspect the primary problem is upstream in the water source.
Regarding whole-house chlorine filtration, I see it as a bit of insurance, in addition to health: chlorine is very aggressive on copper, and as a premium subdivision built in the 50's-70's, many of these homes have exclusively copper water and drain piping, and are built on slab. Water is provided thru a community well, which we're located about a hundred yards from, so our levels of active chlorine are pretty high. Because we have seen some water leaks from copper corrosion, I'd like to minimize the expense of that by reducing the corrosion rate. However, I'm not trying to completely take out the chlorine at POE - just want to knock it down a lot. If I'm knocking it down to a level of a used shower-head chlorine filter, that seems like a good overall compromise to me.

Would a granulated carbon design give me what I'm looking for? I'm guessing that's probably what my current filter is?

I love the thought of having a pressure gauge before/after each filter stage, and your suggestion of 15 psi max drop at highest flow-demand seems very solid. But as an engineer, the dumb-consumer color-coded no-number dials don't impress me or inform me. Having never seen a gauge on our water system, I'm guessing that our average static pressure is somewhere in the 30-40 psi range. Any recommendations on good pressure-gage models to use, and sources to buy from?

I understand the comment on washing the filter, and of course I generally agree. Makes me wonder if adding a large washable pleated filter might make some sense in a 3-filter POE equation?

In this case, it seems that the outer filter layer (of the POU drinking water filter) gets plugged by sediment, and patiently rinsing it off for 10 minutes with a sink sprayer restores decent flow through the filter. Doing it every 2-3 months has enabled it to last a year, though with each rinsing it only restores about 80% of the previous rinsing's flow rate. The conclusion I draw is that whatever the unlabeled bulk chlorine filter is, it's probably on the order of 3-5 microns nominal, and the volume of finer sediment that's getting through is more than the POU's outer pre-filter wrap can handle without plugging prematurely.

BTW, I can appreciate your comment on the $25 chlorine filter. However, what I see is a huge 60% price increase on an unidentified, unlabeled generic filter of unknown performance. It's been working "OK", though not perfect, and for only $15-16 it was a good bulk-pricing deal. But there are other things out there in that common-retail price zone, and some could be better performance. If I'm going to spend $25 on a 10" POE filter, I'm certainly going to know the design/specs/brand of the filter. And if I can find a good performer and then save 20-30% on per-filter cost by buying a case of them at a time, I'm sure going to consider that.

Based on what I've outlined, do I need a better combination of filters? Is one key to this selecting a sediment filter that's better suited for this situation... maybe a 3-5 micron filter with a lot of capacity? Or does the IRB situation mean I should go with a finer string-wound poly and change it weekly, or bump it up to a 20" length? What think the water filtration experts?

[Andy CWS]

Have you tried a pleated type filter? These have more surface area and are reusable.

Andy Christensen, CWS-II

[Gary Slusser]

Brian, I just love you engineer guys, always re-inventing the wheel with your ear plugs firmly in place.

A few more suggestions and I'll leave you alone. You are working on assumptions and I think you shouldn't do that but it is your money, time and equipment.

Culligan twin tank softeners usually have a Fleck 9000 or 9100 control valve on them.

You need a water analysis for iron, chlorine, pH, hardness and manganese.

I do not believe that chlorine corrodes copper and if it does, it can't to any meaningful extent when compared to the other things that corrode it; unless they are using chlorine gas instead of liquid chlorine, right?

So if you have evidence of copper corrosion, you need to look into causes like bacteria (IRB and other reducing types), high DO, CO2, TDS and silica or, a hot water recirculation system velocity problem, or the quality of any electrical grounds bonded to the copper water lines and use of the service line as the electrical ground electrode for the building. And for a few more possible causes goto:

https://www.corrosion-doctors.org

and www.groundwaterscience.com especially the Old GWS site's Rehabilitation and microbiology areas.

You can not have high chlorine and IRB or ferrous iron in your water at the same time. Chlorine kills bacteria and oxidizes ferrous iron converting it to ferric iron.

All waters contain invisible "sediment". When you think about it, it is harmless and is not the problem many people seem to 'feel' it is today.

To my knowledge there are no carbon block filters designed for POE use.

Yes you need a pressure gauge, Lowe's etc. have them for $<10, they screw on an outside faucet.

There are two types of sediment filter cartridges; nominal and absolute.