Sizing a Katalox Light Filter

[Pacman]

Hello,

I am helping redesign a relative's water treatment system. I'd appreciate your comments and suggestions.

Right now they have a cartridge sediment filter and water softener (Eco); both are 20 years old. The softener uses a time clock for regeneration, doesn't soften down to zero anymore, back washes frequently (to keep up) and uses a lot of salt. They also have red/brown staining problems on fixtures and laundry. We've decided to start fresh.

A. Our goals for the new system are:
(1) meter based regeneration
(2) user-friendly, non-proprietary system
(3) reduce staining

B. Water Conditions:
Private Well (approx. 100' deep)
Hardness: 77.4 gpg
Sodium: 298 ppm
Calcium: 357 ppm
Magnesium: 105 ppm
pH: 7.65
Sulfate: 1920 ppm
Iron: 0.64 ppm
Manganese: 3.220 ppm

There is a rotten egg/hydrogen sulfide smell from time to time.

In addition, fine sand and "rust flakes" are also a problem (the cartridge filter catches these).

We realize this is very hard water. The current system has done a good job of taking care of the hardness during it's life, but not the iron and manganese.

C. Household Conditions:
2 people (3 on weekends)
1 bathroom (possible 2nd in a few years)

D. Planned Solution:
(1) Cartridge sediment filter to catch the sand and other sediment
(2) Katalox Light back washing filter to remove the iron, manganese and hydrogen sulfide - size to be determined
(3) Water Softener - Fleck 7000SXT 2.5 cu. ft
To maximize salt efficiency, I plan to set the unit to 50K capacity and use 6 lbs. salt/cu. ft. This means the system will regenerate approx. every 5 days.

My Questions:
(1) How do I calculate the size KL filter I need to use? What should I factor into the calculation? service flow, iron, manganese levels?
(2) What are the downfalls of a KL filter? They almost seem too good to be true (when compared to other iron/manganese removal options). Is it worth the cost for our water conditions?
(3) How often should KL be back washed?
(4) Is it worth it to up-size to a 3.0 cu. ft. softener? The larger the unit, the harder I think it will have to work to backwash because of the increased resin volume.
(5) Can the 7000SXT be set to up-flow brining?
(6) I've had the 5600SXT before and really like the valve, but I think the soft water brining offered by the 7000SXT is worth the upgrade since our raw water is so hard. What are your thoughts?

Thank you

 

[Reach4]

http://www.watchwater.com/systems/kl_system.php is a calculator that can be of use. The backwash GPM required is usually higher than the numbers they cite unless the water is rather cold.

http://www.qualitywaterassociates.com/softeners/sizingchart.htm and continue to the calculator on the next page. Sounds like you may have been there already. After the KL filter, iron should be down to near zero. If you undersized the KL a bit, the softener could probably pick up the slack.

Maximum backwash for 5600SXT is 7 GPM. Today the 7000SXT is not much more expensive.

I would put the cartridge filter after the KL.

If you get H2S smell in hot water only, I like a powered anode. Protects like magnesium.

I am not a pro.

 

[Sponsor]

 

[Pacman]

Thanks for the links Reach4.

Yes, I've been to the softener sizing calculator before and I understand the calculations.

I appreciate the KL calculator. Based on it, I should look at a 2.0 cu. ft. KL filter.

Why do you recommend the cartridge filter after the KL? I was thinking before because I don't want the sand to plug it up. Or will the KL filter out the larger grains and let the cartridge pick up finer grains?

 

[Reach4]

The backwashing KL filter is supposed to serve as a filter down to about 3 microns. http://www.purewaterproducts.com/img/docs/manuals/Katalox-Light.pdf Then the cartridge filter can serve as both a second filter and an indicator I think. I don't know if the sand will backwash out of the KL, but I would have guessed so. Somebody with some experience may give you some insight. The TwistIIClean is well-regarded if you get a lot of sand and want a pre-filter. It can be cleaned without changing out an element.

Regarding upflow brining, there is a disadvantage in real situations, but I forget the problem. The 7000SXT can let you have a second backwash to mix up the resin again after the downflow brining, so that the most-regenerated resin is not concentrated at the top.

 

[Bannerman]

My Questions:
(1) How do I calculate the size KL filter I need to use? What should I factor into the calculation? service flow, iron, manganese levels?
Due to the water needed to properly backwash the media, the size of a filter system is often limited by the well & pump flow capacity.

A 2 cuft K-L tank (12") will require 8-12 gpm for back washing, depending on water temperature.

What is the continuous flow rate that your system can support?

(2) What are the downfalls of a KL filter? They almost seem too good to be true (when compared to other iron/manganese removal options). Is it worth the cost for our water conditions?
Although your water does not contain a high enough amount of iron to justify a separate iron filter, there is a substantial amount of Manganese to be dealt with and you also report a Hydrogen Sulfide issue that a softener cannot remove. While K-L is one option that will also remove the small amount of iron, there are other options including chlorine injection using a retention tank to oxidize the iron, manganese and H2S to permit the residue to be filtered out prior to the softener.

(3) How often should KL be back washed? Probably weekly.

(4) Is it worth it to up-size to a 3.0 cu. ft. softener? The larger the unit, the harder I think it will have to work to backwash because of the increased resin volume. The sizing calculator here: http://www.qualitywaterassociates.com/sizing.php specifies 4 cuft as the minimum size to be considered for 2 persons at 78 gpg and no iron or manganese whereas a 6 cuft is specified for 3 persons. A 16" diameter resin tank (3.5 - 4 cuft) would usually utilize a DLFC rate of 7 gpm to backwash the quantity of resin contained.

(5) Can the 7000SXT be set to up-flow brining?
Yes, but would require internal modifications in addition to programming. Up-flow brining is not usually recommended.

(6) I've had the 5600SXT before and really like the valve, but I think the soft water brining offered by the 7000SXT is worth the upgrade since our raw water is so hard. What are your thoughts?
The largest softener appropriate for the 5600SXT is 2 cuft (12" tank) or 1.5 cu ft (10") for a filter. A 7000SXT supports a higher service flow rate and is appropriate for softeners or filters using 8" - 24" tanks.

 

[WellOff]

Pacman, that's pretty high levels of Mn. Well, to me that is. I've been whining about a lowly .19-ish number for a couple of years now: I've documented much of this here: https://terrylove.com/forums/index.php?threads/battles-with-manganese.59540/ After finally getting a good testing of KL (refer to my link) I can emphatically state that it DOES deal with Mn. I am now in need of verifying whether my current system can support KL, so here goes my query re sizing:

Well pump output: 10gpm (well output 30 gpm)
Piping: 3/4"
Pressure tank: 80 gal (I believe actual water capacity is 24 or 26 gallons)
Backwash unit: 7000SXT
Backwash tank: I believe, 10" x 44" - spec'd for 1 1/2 cu-ft of media (originally/currently Catalytic Carbon)

According to the vendor of the backwash tank it's rated for 5gpm.

Household uses roughly 100 gal/day: actual consumption is about 75; backwashing and flushing of contact tank tends to bump this up.

Water quality/issues:

Fe: 2.1 ppm (roughly)
Mn: 0.19 (roughly)
pH: 6.9 - 7.0
Hardness: 33 (whatever)
IRB (and some coliform has been detected)

If I plug my numbers into the watch-water KL sizer (http://watchwater.com/systems/kl_system.php) it tells me I need 2 cu-ft of media, which, I figure, my size of tank won't support. Do I need to actually specify 5 gpm even though I don't really use that much? I'm not sure whether the 7000SXT is throttled (to 5gpm- I think that this might be for the backwash discharge valve?) Also stated is a contact time of 175 seconds; not sure if I could support this or not: I've got a 40 gallon contact tank for H2O2 oxidization and bacteria (IRB and other) just ahead of the backwash filter, the recommended contact time is 20 minutes, so maybe 3 minutes on/in the backwash tank isn't a concern (though I am not sure how much water exists within that tank).

Will my current backwash tank and unit be capable?

 

[Reach4]

Do I need to actually specify 5 gpm even though I don't really use that much? I'm not sure whether the 7000SXT is throttled (to 5gpm- I think that this might be for the backwash discharge valve?)

The backwashing filter DLFC on your 7000SXT will need to be raised from 5 GPM to maybe 8 GPM for a 10x54 tank with KL. 7 may be sufficient.

The flow rate for the calculator is based mostly on what you use in the house at the same time. A 2.5 GPM shower plus another 2.5 for something else would give your 5 GPM. A tub fill could take 5 GPM or more by itself if you turned the faucet on full. If you were conscious about it, you could keep the flow rate in the hose at some smaller level. Exceed the level, and you leak some Mn through... not terrible.

The softener backwash will be going through the KL, but that would be usually a lesser flow than the filter backwash, and that would seldom happen while other things are drawing water.

 

[WellOff]

Yeah, there's always been the ability to overrun the system. Maybe put a flow restrictor in post backwash filter (or final filter)?

The backwash tank is 10" x 52" (from bottom to neck).

I have no softener, so no issues there. But I do have to be careful of overdrawing from the (40 gal) contact tank: and for this reason I have the time set low on both the wash and rinse cycles (3 minutes per)- the water runs clear after a pretty short amount of time; backwashed every other day.