With your water use characteristics, hardness level, and # of people and bathrooms SFR is a HUGE consideration in sizing your softener and not to be a footnote in the calculations.

I'd like to see test results from comprehensive water test.

Why concern yourself with pre-filters? Something in the water now that you don't like?

Why a turbulator?

Why SST-60?

The Fleck SXT series is easy to program and the Fleck electronics have proven to be reliable.

My numbers suggest a much larger softener than 2.5 cubes and without iron you'd want to regen every 6 or 7 days and waste less water and salt.

"... a little worried about it being 3/4"

What diameter is the plumbing in the home?

I understand that SFR is important. I shouldn't have just guessed at it you're right. I just measured, as a first step towards figuring SFR, 8gpm at the jacuzzi, which is the highest flow faucet in the house. The plumbing at the softener inlet is 1" copper.

I haven't done a personal water test, but the local water company has done a comprehensive water test. What other parameters are important other than hardness, iron, and manganese?

Prefilters for sediment. There is a hot water recirculation line in the house and I thought that not having sediment in that continuously flowing loop could reduce likeliness for slow constant damage to the pipes. You see we did have a pinhole leak in one of our pipes recently that caused a minor flood. The house and plumbing are 10 years old and this is an old line that leaked. I just thought that reducing sediment could mitigate that. I could be wrong also. :)

SST-60. I had this in my previous house. Well I chose that partially because they have a datasheet/tech bulletin. I like datasheets. It's also made here in the US. I think the other generic resins that I've used for my folks softener and for my brother in-law's softener were from Pakistan. I would prefer US made stuff even if it costs more. My other resin option is also a generic resin so I don't have a datasheet for that. I know that the SST has slightly better salt efficiency and can be rinsed easier/shorter (wasting less water). In my scratch note calculations I compared a twin tank 2.5cuft softener with SST-60 and a 3.5cuft softener with generic resin and calculated for a 4lb salt dose I could save 10 lbs of salt per month, so three bags per year. Not a great cost savings, but I would prefer not to use the extra salt if avoidable.

Turbulators ... don't know much about them. I have not had them in the past and was not planning on using one really. Seems there are theoretical benefits when used for high iron or high sediment water, but my previous installations used a gravel bed and straight riser tube.

I like easy to program. And reliability. Fleck's 9100SXT should be a good bet then. My only concern was the 3/4" size for the 9100SXT. It seems that 3/4" is the only way it comes. At least that's what ohiopurewater has where I've been browsing mostly. They do offer it with a 1" stainless bypass though so that's probably what I would get. Again, the house plumbing is 1" at the entry point.

Ok. Regarding SFR, I don't really know what I need. I couldn't find any easy way to calculate it based on number of bathrooms, etc. I'd prefer to size the softener for current 5.5 baths and if I have to I can get another softener for the addition, probably a single tank. Or just leave it as hard water because of relatively little use. The vendor recommended a 3.5 cubic foot (x2) softener for my needs. I downsized it to a 2.5 to use SST-60 at about the same cost and better efficiency, with the perhaps bad assumption that the softener would be adequate for my home SFR.

If you correctly calculate the SFR required by the number of bathrooms and the number and type of fixtures you'll require an SFR great than 8 gpm.

Of course, you can install 10 Jacuzzis in a house but only get the SFR that the 1" pipe servicing the home and whatever size the supply pipes in the walls are so that's what you have to look at first.

I'm not a plumber and perhaps you should get one to do the plumbing math cause I don't think a 1" service will come close to meeting the SFR that all the stuff you have requires... geez, you live in a hotel!

The resin in softeners makes a very good sediment filter and whatever collects gets gone in the backwash of the regen. If you have a serious sediment problem then filters may be required but even two paralleled 4x20 5 micron filters in big blue housing will restrict the water flow and effect the backwashing of the softener.

The water company tests as it leaves the treatment facility and those results are not always reflective of the water conditions at your water meter after running though miles and miles of (old) pipe.

Hardness, iron, manganese, PH, TDS are all good to know. Might that pinhole leak been from low PH water?

A 1" bypass won't make any difference if the internal valve size is 3/4". I prefer the Fleck 3/4" Noryl bypass... more reliable and Noryl is nifty stuff.

CK Moore recommends twin 3.5 and you downsized it?

In your circumstances I'd opt for a quality resin like Sybron C-249. No reason to spend the extra money for SST-60 and twin 3.5 cubers will get you more SFR than twin 2,5 cubers will. Go too small and you'll get hardness leaking through.

I gathered that SFR is not just a single faucet's measurement, but the highest flow source is a good place to start. As I've said, there's really no way that I have found to calculate a realistic SFR. I can tell you that we have a couple people taking showers at the same time commonly. Maybe 3 people sometimes. Worst case, probably there are 3 people taking a shower, jacuzzi running full blast to fill (again, jacuzzi use is extremely rare), washer running, dishwasher running, and a toilet flushing. No idea what that works out to, but I do know the showers are limited to 2.5gph by flow restrictors. So 8 for the jacuzzi, 7.5 for the showers, guessing another 2.5 for the toilet, maybe another 5 for the dishwasher and washer. So an educated guess would be around 25gpm. Maybe I did undersize it.

I was looking at the chart on Purolite's datasheet titled "Leakage vs Regeneration Level". This shows two curves comparing standard C100 to SST60 resins and the amount of leakage compared to the regeneration level. At my selected regeneration level of 4 pounds salt per cubic foot, the SST shows more than 50% improvement in the amount of leakage. I may have misinterpreted this to mean that it should have more than 50% better SFR when compared to a cubic foot of regular resin. This is partly why I thought it would be OK to downsize to 2.5 cubic feet when using the SST-60 resin.

CK Moore actually recommended a twin 2.5, but that was after I gave him a guess at SFR of 15 gpm, which now seems like it is too low. Even a 3.5 cubic foot softener can "only" handle 22 gpm. Bigger than that would be commercial sized I'm guessing.

I'll go with your recommendation with skipping the sediment filter. Also, I see your point about water testing. i always thought that since they have much more testing equipment at their disposal, the water company's test results must be better, but your point about old pipes makes sense. At least for iron. Would one of those home test kits that I can pick up at a home store suffice? I'm pretty sure manganese is not going to be one of the things they test for in those home kits.

Noryl bypass preference noted. Unfortunately, I don't see a Noryl bypass option. I see Noryl yokes, stainless yokes, and stainless bypasses.

So for now I need to get the water tests done. Once I know that, I'll update this thread. I really appreciate your help.

Anyone you ask for help with sizing a softener has to go on the information your supply. If your info is faulty then so will their recommendations be.

The following is meant with only the best intentions...

You know enough to not get what you need. You're taking a flash course in water treatment and don't know what you don't know.

I can help you with how questions but I'm not an teacher and don't do why questions beyond a certain point.

That said...

There a many, many things that are not listed on web sites that are readily available if you ask for them. CK likes the SS bypass and I like the Noryl bypass for the material and it is shallower allowing the softener to be backed up closer to the wall. CK doesn't think a gravel underbed is necessary below a certain size softener and IMO there is no reason not to have a gravel underbed. CK is knowledgeable and reputable but he is in the business of making a profit and I have nothing to sell you... I'm just trying to help.

As I already said, a plumber can make a list of all your fixtures and calculate the SFR required... that's how they come up with what size water service a house needs, right?

Unless the softener is properly sized for the required SFR then hardness will leak through at peak demand so then what's the point of a softener if you're getting hard water?

You study, you read, you think, and then you overlook the most important consideration in sizing a softener.

Yes, it looks like you need a bigger than 25gpm SFR softener

You may have a greater GPM demand than the 1" service to your house can support and that makes a lot of this discussion academic.

Hazarding a guess that your required SFR will be high enough that a 3/4" control valve body might be a problem. Unless you want to go with a Fleck commercial control valve at a FAR higher cost perhaps you should be looking at a larger bore residential control valve like a 7000 on a single resin tank softener.

The down side to a single tank softener is that you get untreated water during regeneration and a BIG softener like a 3.5 cuber will take a lot longer to regenerate than the 90 minutes a moderately sized softener takes in the middle of the night.

On a twin you only get the SFR of each tank when it is in service but that flow rate is mitigated when one tank is in regeneration because the softener supplies soft water to regenerate the depleted tank.

Twin-tank systems are sized very differently than single-tank systems. I think with only 18gpg a 2.5 or 3.5cuft softener is not needed.

I don't have the Fleck 9100 data sheet with me but I could use a Kinetico twin to compare. The model I would recommend would be a MACH 2100s OD. This is a paraflow (as opposed to an alternative flow) unit. That means water is passing through both tanks at the same time except during regeneration (90 minutes).

At 18 gpg you would regenerate every 957 and use about 5.5 lbs. How often that would happen depends on the volume you use on a case by case basis. The back wash rate maximum is only 3gpm which would be a lot less than much larger units.

These tanks contain 1.5 cuft of resin each in a standard mesh. With your level of iron, a turbulator is unnecessary and a standard mesh resin will be more than satisfactory.

Although maximum SFR should always be a consideration, in reality it is an extremely rare occurance and as you have said most likely no more than three people using water at once. The 2100 has 21gpm flow rate with 31gpm peak flow rate. Unfortunately, Fleck doesn't make this variation. The 2100 is designed with 1.25" plumbing and comes wioth a bumper to bumper warranty---including resins.

These flow rates are calculated at the point where pressure drops 15psi not where hardness necessarily comes through.

I do recommend a sediment prefilter, if it 'is not needed' then it would not clog up and serve as a cheap protection against the occassional sediment problem and it would not be a hinderance to flow rate. I tend to disagree that a softener should serve as a 'filter'. Resins were neither designed to act as a filtration system and can be negatively affected by continuous sediment intrusion.

Your idea of parallel two big blue filter filter with pressure gauges is a very professional and excellent choice. Most don't do that to that extent (usually one 10 x 2.5") and do so without issue. I would go with a 20-micron, though. Pleated fliters are reusable to a point. These will definitely not restrict flow to any degree noticable and your pressure gauges will attest to that. You always have the option of leaving them empty.

And if they did get clogged, give yourself a pat on the back for not dumping all that foreign matter into your expensive unit. Often sediment is heavier than resin and falls to the bottom of the tank where it accummulates and isn't backwashed out. I have seen a lot of mug coming out of old junk softeners where a prefilter would have gretly extended service life. A very cheap and good insurance; that is a good choice.

I would say you have a very firm and sound understanding of water treatment as a homeowner.

Andy Christensen, CWS

Let me second what Andy said. DO NOT skip sediment filtration if you have a sediment issue. Your softener should not be used as a sediment filter unless you want to shorten softener life, plug your softener resin bed with heavy fines, damage resin beads (which are soft relative to most sediments) and generally cause yourself headaches.

Also, although I am do not typically recommend Kinetico because I think they are overpriced, they may be a very nice fit for your situation since they have systems that may be run in parallel during high flow times.

The OP did not say he had a sediment problem rather he said "Prefilters for sediment. There is a hot water recirculation line in the house and I thought that not having sediment in that continuously flowing loop could reduce likeliness for slow constant damage to the pipes. You see we did have a pinhole leak in one of our pipes recently that caused a minor flood. The house and plumbing are 10 years old and this is an old line that leaked. I just thought that reducing sediment could mitigate that. I could be wrong also."

The OP imagined that sediment caused a pinhole leak with no evidence. He didn't mention clogging of sediment filter or seeing sediment from his municipal water system.

If there is a sediment problem then by all means it needs to be addressed and I have often recommended parallel 4x20 big blues in parallel with pressure gauges before and after to monitor element condition. I am not a fan of installing a filter unless circumstances show they are required but not 5 micron elements..

I have come across Kinetico paraflow system before and they are an interesting design with pluses and minuses like all other designs. Regardless of the softener design the volume of resin in a given size tank sets the SFR and no advertising or marketing department gets to change the laws of physics.

While the paraflow offers the SFR of both tanks when in service that flow rate drops to half whenever one tank is being regenerated. Since twins regenerate whenever the count dictates one would never know when they'd be running on one tank with insufficient SFR to accommodate washing the clothes while a couple people are using a couple of those 5.5 bathrooms and someone might be in that Jacuzzi while hard water leaks through. Again, seems to me that if you're paying for soft water then you ought to get it.

Andy said "At 18 gpg you would regenerate every 957 and use about 5.5 lbs" so let's see... 7 people x 60 gpd = 420 GPD so that 2100S OD will regenerate one tank every 2 days or so using 5.5 pounds of salt and how many gallons of water? That's three or four tank regenerations a week.

In my experience Kinetico salesman dismiss SFR as a rule and often recommend undersized softeners that regenerate very often. At least Andy acknowledges SFR and that puts him a notch above most Kinetico salesman I've come across.

Thanks for the added input guys. I will be picking up a water test kit this weekend hopefully.

Regarding the sediment filter, I do not know for sure in this house that there is a sediment problem. I do know that the existing softener that has been in service for 10 years max is spent. It may have been spent by the previous owner due to abuse like not using salt. Perhaps it was fouled by sediment. In my previous home about 5 years ago I installed a parallel set of 10x2.5 inch sediment filters and ran 20 micron melt blown elements in them. I did not know then to install pressure gauges at that time (I learned that from this forum and justalurker - thanks!). Anyway, the clear housings allowed me to see the sediment build up. Within a week, they started accumulating brown "stuff". I would change them every 3-6 months, so I never actually experienced a perceivable flow reduction in the home. That home is about 2 miles away from my current house and the water supply is the same. I don't know if this constitutes a "problem" but I thought a sediment prefilter would be cheap insurance. If the elements do not accumulate stuff or I don't see a pressure drop in a 6 month period, I could just discontinue using them.

I think you are on the right path.

pH 7.5
chlorine 0.2
iron 0
hardness 20
copper 0
nitrate/nitrite 0

I just figured out the size of the existing softener. 1 cubic foot! Seriously! Unbelievable that anyone who knew what he was doing would put something that small in a home this large. Oh well.

Not that uncommon to find grossly undersized softeners... think of all the people who buy Sears, Whirlpool, GE, Morton and install them everywhere.