Help choosing a water softener

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New Member
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Ann Arbor

I have well and my water has the following characteristics:
pH: 7.54
Iron: 0.4 mg/L
Manganese: 0.05-0.1
Hardness: 17 GPG
TDS: 244
ORP: 120 mg/L

It’s a 4 bedroom home with 2.5 bathrooms and 3 occupants.

I’m trying to choose a water softener and I’m wondering if the Fleck 9100 SXT would be a good choice? The twin tank sounds appealing as it’s my understanding that it guarantees efficient operation, as I think it only regenerates when it needs to as apposed to regenerating on a timer. Plus, I think it’s always able to supply soft water (even during regeneration).

My understanding is that single tank water softeners, which regenerate on a timer, can end up regenerating before they actually need to (which wastes water), or can give you hard water if you happen to use more water than expected before the scheduled regen cycle kicks in. I understand that some control valves might be more sophisticated than a simple timer and may attempt to predict water usage and schedule their own regeneration cycles, but I’m not sure how well these work and if they compare well to the efficiency of a twin tank water softener.

It’s honestly challenging to find reliable information on this topic (twin tank vs single), as most of what I find is marketing literature.

Our number one goal is to prevent rust stains on fixtures, in toilets, and in laundry. We’d also like to maintain good water pressure and avoid wasting too much water.

Other questions include:
1) Do I need a sediment filter before the water softener?
2) What size water softener would be appropriate?

Based on my numbers, I think I might need a softener sized between 42,000 and 60,000 grains:
3 x people x 100 gal x 20 hardness (rounded up a bit for iron) x 7 day regen = 42,000.
But I’ve seen some people do that calculation with a 30% reserve, which would make the size 60,000. That strikes me as huge... my gut tells me 48,000.

3) Would an iron filter be necessary?
I suspect not, but figured I may as well ask the question to be complete.

Sorry if these questions have been asked before. I did some searching and didn’t find exactly what I’m looking for.

Thanks very much,


Water systems designer, R&D
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Ontario California
A complete lab report would be helpful but I will attempt to answer a few questions.

Twin alternating is not necessary, all modern softener operate on a metered basis. You will gain a tiny amount of efficiency with a twin alternator but at your moderate hardness it is not needed. The difference in efficiency will be miniscule vs. the more complex twin alternating valve. As to iron reduction ahead of the softener, recommended but not overly necessary. A fine mesh resin and some regular cleaning of the resin bed and you should do fine. Pre filtration is not typically necessary but I do like to see the Atlas Hydra ahead of Water treatment equipment,
Follow this with a polishing filter and a UV and all is good.
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