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Is my water softener sized correctly?

Posted by AcrossThePond (My Page) on
Sun, Oct 30, 11 at 17:09

Hello everyone from England!

I wonder if you could please help me determine if our new softener is sized correctly. Our old softener (5600 economiser) gave up and the company that we've used for years replaced it with a new unit a few weeks ago. Since being replaced I've kept an eye on it and because it is digital (5600SXT) I can see what's going on with it and monitor it more readily.

Our profile:

- Family of 3-4 (2 adults, 1 yr old, 1 extra baby planned!)
- Four bedroom detached house
- One washing machine
- Dishwasher
- 1 jacuzzi bath, 2 showers (power shower type), 3 toilets

Our unit seems to provide about 2050 litres (541 gallons) after a regen without taking any reserve into account. Our water hardness reported by the water company is 21 degrees clarke. Based on taste/appearance, I don't believe we have an iron or chlorine problem but I found this information from our local water company:

HYDROGEN ION (pH) pH value Min=7.450, Mean=7.712, Max=7.970
IRON ugFe/l Min=< 2.300 : Mean=< 6.571 : Max=38.065
CHLORIDE mgCl/l Min=56.000 : Mean=70.750 : Max=77.000

Not sure if any of these are an issue.

Basically it varies a bit higher or lower, but we seem to use around 600 litres (158 gallons) a day, but I would expect this to go up if we have another kid. The softener was originally set for 24 on the hardness so I changed this to 21 - this gave us a bit more capacity, not sure if it needs a bit more for the iron/chloride. It is set for 480 reserve, which isn't enough either. So based on our usage of 600 litres a day the 2050 litre (541 gallons) range is only normally enough for 3-4 days which as I gather from reading this site, unless I'm wrong, isn't optimal and the ideal being weekly or every seven days? If I set a more realistic reserve it would be more like 3 days. It is this that leads me to believe the unit isn't sized correctly, although I could be wrong.

I just measured the unit and I believe it is 0.043m3 or 1.5cu ft.

The settings on the machine are as follows:

DF Ltr
VT df16
NT ---1
C 43.0 x 1000
H 21
RS rc
RC 480
DO Off
RT 2:00
BW 3
BD 40
RR 3
BF 9
FM t0.7

Unless there is something wrong with my settings I was going to speak to the installer and ask him to upgrade the unit to the right size - but the question is what would I actually need? Would this a big deal for him to change? I don't mind paying extra for the right size, but I have no idea how much extra it should cost.

Many thanks

Follow-Up Postings:

RE: Is my water softener sized correctly?

Happy to help you include the required info...

You have 18 gpg hardness.

I need to know what the BLFC sticker says (near the brine line connection on 5600) so I can determine the salt dose. It will say ,25 or .50 or .75 or something like that.

Off hand, with 4 people (projected occupancy) 1.5 cu ft is undersized, especially with a Jacuzzi and two power showers. The SFR with 1.5 cu ft of resin will hamper flow at peak demand and hardness may leak through. You are regenerating more frequently than you should and (I think) you're using more salt than you should.

I'm not sure if the way your 5600SXT is programmed is how they do it over there or your water treatment people are as underwhelming as most of those we have over here are. Since physics and chemistry is rather universal, at least on the planet, I'll take issue with their programming.

I would have recommended a larger softener and programmed it for efficiency instead of a smaller and less efficient unit. As your family grew to full size my softener recommendation would have been more cost effective to operate, less wasteful of water, and had a longer service life.

RE: Is my water softener sized correctly?

Hi just

Thanks for your offer of help and for replying to my message - most appreciated.

Good to know what the hardness - thanks for that. I take it there was no iron/chloride issue?

There is a pipe above the inlet with a sticker that has the following - hopefully it's what you're after:

Inject: 000
DLFC: 0.9
BLFC: 0.12

From the past few weeks of using it, it does seem that this unit uses less salt than the econominder, but that's just gut feel. Salt is not too expensive over here (£5-£8/$8-$12 a bag 25kg/55lbs) but nobody likes the idea of wasting salt/water. I looked at the diagnostics this morning after heavy weekend use and the max peak flow is 15.7.


RE: Is my water softener sized correctly?

A 5600 Econominder should use the same amount of salt as a 5600SXT IF they are both sitting on the same volume of resin and IF they are set up the same.

With respect, in order to help, YOU need to convert any numbers to what we use over here. I'll help but I won't do arithmetic for you.

BLFC is the number BUT 0.12 WHAT? We use gallons per minute (gpm)

Peak flow is 15.7 WHAT? We use gallons per minute (gpm)

Salt is not expensive but wasting water can be and regenerating more frequently shortens resin life and that costs you sooner than later. As your family grows you'll realize the added cost of inefficiency... and how much might salt and water cost in 10 years, 15, 20?

Your softener is undersized. Whether you choose to have that corrected or live with it is up to you.

RE: Is my water softener sized correctly?


Sure, no worries on the conversions.

Peak flow must be in litres so 3.45 gpm

Forgive me, but I don't know what BLFC is or means but if I assume it's litres then 0.026 gpm. There are no units with the number so it's a guess that they are litres. Hopefully the conversion to gpm looks like a valid number to you.

I agree totally about getting the right size and that is why I'm here.

Thanks again for your help.

RE: Is my water softener sized correctly?

If you go to this link click here you will download the USA service manual for the Fleck 5600SXT. On page #24 item #38 is the BLFC and on the next page you will see it is available in 0.25 or 0.50 or 1.00 gpm. No 0.12 size to be found. You need to find a service manual for your market and be sure what the BLFC size is. I can't seem to get to the Pentair GB site.

To get this right there can't be assuming or guessing.

BLFC = Brine Line Flow Control

The BF setting is minutes (in the USA) so BF = # of minutes x size of the BLFC = volume of water which gives the salt dose.

RE: Is my water softener sized correctly?


It seems a service manual for this unit could prove to be very elusive as it is a re-branded product created using the fleck value. I have worked out the model number though: NuWave MD400 - no website for NuWave. The brochure numbers are identical to my findings - helpfully they quoted at 21 hardness!

Maximum capacity at 21 degrees clarke (300mgl) - 2045 Litres (449 gallons)
Salt used per regeneration - 1.6kg (3.52 lbs)
Amount of resin - 10 litres (2.19 gallons)
Water used per regeneration - 50litres (10.99 gallons)
Minimum flow rate required per minute - 1 litre (0.21 gallon)
Maximum flow rate per minute - 50 litres (10.99 gallons)
Inlet and outlet connections - 3/4" (standard washing machine size)
Drain and overflow connections - 1/2" barb (Garden hose size)

I know you said you can't assume but I think the 0.12 must be gpm. Given that their values double up it would make sense that the next step is 0.25gpm and so on. I can't believe it is litres. Do any of the above numbers help to confirm that at all?

Using your calculation it gives us: 9 x 0.12 = 1.08 gallons (4.9 litres) - does this match up with anything above?


RE: Is my water softener sized correctly?

One gallon of water dissolves 3 pounds of salt anywhere in the world.

Reading up on that web site that softener only has 10 liters of resin... that's only 0.35 cu ft of resin. That' thing is going to regenerate way too often. Average water use is 60 gpd per person so three people = 180 gpd or regenerate about every 2.5 days.

Over here you'd want a 1.5 or 2.0 cu ft softener and it would regenerate every 7-8 days with a reserve set aside and get an efficiency of about 3333 grains of hardness removed per pound of salt.

Either chemistry and physics works differently on the other side of the pond or something is being lost in the translation.

Could be that floorspace is at a real premium in European living spaces so they sell lots of those tiny (toy) softeners and then work the hell out of them by regenerating far too often but you lose SFR and hardness will surely leak through at peak demand.

RE: Is my water softener sized correctly?

It does seem that this size of softener is more readily available/marketed here than larger systems. Having seen the rather large garage sizes at some places in the states I guess space is more readily available.

I'm trying to figure out if I increase the salt dose what the increased capacity might be. I suspect this unit has been optimised but I might be wrong so there may be little point in doing this, but I'm curious to understand it.

At 1.6kg (3.52lbs) I get 43,000 grains which at 21 degrees clarke hardness yields 2047 litres (450 gallons) - 4300 / 21.

I know how to change the amount of brine by changing the BF setting but what I can't quite figure out is if I were to increase that how do I calculate the resulting capacity? I've tried to find the formula on the internet but have failed.

RE: Is my water softener sized correctly?

1 cu ft of resin yields 20k grains hardness removal @ 6 lbs salt dose. You can work your math around that if you must, but...

With your softener you are dealing with such a small amount of resin (.35 cu ft) that changing the salt dose will achieve little difference. I think the design goals of the tiny softener are programmed in and a little fiddling is not going get you much.

A more important concern is whether the water is holding ZERO hardness all the way until regeneration. Get yourself some hardness test strips and test the water as it approaches regeneration. If the water holds ZERO hardness till the softener regenerates then fahgettaboudit.

If the water goes hard before regeneration call the seller and have them correct the problem. The solution may be a programming change or it may be the next larger tiny softener.

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