Irrigation Well Iron removal system recommendations ***UPDATE***

[ByteMe]

If you are asking for a lawn care perspective, no clue here... Always hired the Mexicans to take care of that.

And no, I ain't racist! I married one of the beaners! ( I call her my beaner baby)

OK, insensitive yes.

 

[Brother Jack]

reach4....the amount of water needs is very much soil dependent. I have a sandy base....I had to truck in loam...and yes I have KBG and a fescue mix. I have good drainage but require more water. My neighbor has a higher clay content and more shade..needs less water.

I have a professionally installed irrigation system that covers a total of 14k sq ft...5 zones 40 head of various output. Not all the zones are equal but they all put out 14-15 GPM so the pump doesn't cycle. they simply change the plastic nozzles on each head once they get the out put close. the irrigation guy was great. Once he had the basic layout, he tweaked each zone for the output so the pump pressure stays steady.
Most lawn people in the area recommend 1-2" of water per week....but of course it's all on how it is delivered. I got 2" of rain yesterday over 3 hrs. most of that ran off down the drain. I probably won't irrigate for 3 or 4 more days. With cooler weather coming into fall, I will back down to once a day watering when needed...then shut down end of October until April 20th or so...

See? I'm not a terrorist...just a simple criminal

 

[Sponsor]

 

[Bannerman]

It's often said that grass is the most expensive vegetation.

Not exactly what you're looking for but here is a link to info on flow and backwash of various media including Katalox.
http://www.purewaterproducts.com/articles/backwash-chart

 

[Brother Jack]

My first set of calcs should be spot on... And take into consideration max flow and back washing needs (backwash one at a time, everyday)

8cuft of katalox is not enough... I calculated 8.964

When you did your calcs...which completely lost me BTW...you used 7.47ppm x's 3600 gpd = 28892 removal amount..
The 7.47 ppm..I thought that was mg/l.....isn't that per liter?

I'm just a tax accountant...math isn't my forte' LOL

 

[Brother Jack]

It's often said that grass is the most expensive vegetation.

Not exactly what you're looking for but here is a link to info on flow and backwash of various media including Katalox.
http://www.purewaterproducts.com/articles/backwash-chart

thanks Bannerman. yes I've seen that. I've spent a lot of time reading posts on this board forum and it's been great. I saw that link in other posts here. there is also this one...http://www.purewaterproducts.com/img/docs/manuals/Katalox-Light.pdf
It's been pointed out to me that the spec sheets are good starting points but sometimes you need to tweak the engineering..have decent equipment ..water temp, O2 levels etc all can change the results.

 

[Bannerman]

The manufacturer's product info for Katalox Light indicates:

Iron removal capacity - 3000 mg per Litre of KL media = 85,000 mg/cuft (approx)

http://www.purewaterproducts.com/img/docs/manuals/Katalox-Light.pdf

 

[ByteMe]

Yea, I can do math... but stoopid on most other areas.

I believe the data sheet is saying 1cuft of katalox lite will remove 85,000 ppm. Just add up ppm level of iron per gallon.

If the above is true.

85000 / 7.47ppm = 11,378 gallons of iron per cuft of Katalox Lite.

Hmmmmm, this would be a much smaller system. I believe your system will need to be sized for flow/backwash rate more than capacity.

One of you pros want to run the math?!?

 

[Bannerman]

The capacity information I included in post 26, was already mentioned by ByteMe in posts 6 & 7 of this thread. I couldn't follow his calculations as I didn't earlier understand where his figures were obtained from and as he included calculations on 7 days, I don't understand why that was included.

In thinking about the ratio of mg/L being equal to ppm, that is applicable for the iron content in the water but I'm not certain a ppm conversion will work when calculating capacity in a volume of media ie: 3000 mg per Litre of K-L.

As the confirmed iron content is 7.47 mg per Litre of water and as there are 3.78541 Litres per US gallon, then your iron content is 28.277 mg per US Gallon.

28.277 X 3,600 Gal/day = 101,797 mg/day of iron to remove.

As K-L has a stated capacity of 85,000 mg/cuft, then 101,797 / 85,000 = 1.2 cu/ft of K-L media/day, assuming iron removal only, with no manganese or sulphur also consuming capacity.

As a 1.5 cu/ft filter cannot support a 14.5 GPM flow rate, then a larger system is required to meet/exceed your flow requirements. While more media will provide additional capacity so that daily backwashes may not be technically necessary, you probably would want to backwash daily so as to ensure full iron removal at your full intended GPM flow rate.

 

[ByteMe]

For the record, when I figured 7 days... It was a brain fart, was thinking of a softener.

 

[_John_]

You can't size for the minimum of the Katalox capacity as you'll get bleed thru near the end of a cycle.

85000 mg /7.47 mg/L= 11,379L treated/cu ft. / 3.8 L/G= 2995 gallons/cu ft. media capacity. (again, you can't use all that and expect to get adequate filter performance).

I personally wouldn't size a unit to have the backwash be the max water your pump can put out. Considering the flow rates, and backwash requirements, and that (as dittohead has pointed out in prior threads) Katalox's backwash requirement is a "best case", I'd lean more towards 3 2 or 2.5 cu. ft. units. If you did a daily backwash you'd never use more than 1/5 of the units "capacity" and you'd have well over the rated flow rates per man. specs. Backwash rates would be 9-11 gpm (which I know is higher than their specs).

I do think 2 14" units would cover you as well, but I personally have a control valve that is similar to what I think you're talking about, and I have my doubts as to how reliable a system setup to backwash at the max the valve was capable of would be.

(I know this post is now redundant...but I spent enough time on the calcs that I wanted to post anyway)

 

[ByteMe]

Ha, so my first set of calcs were correct. Imagine that!

Never mind, they aren't! Dang math.

Anyone have a link to a guide for determining backwash intervals for katalox lite?

Searching on my phone finds nothing.

 

[Reach4]

85000 / 7.47ppm = 11,378 gallons of iron per cuft of Katalox Lite.

That would be gallons of water, and it would be used to calculate how often you need to regenerate (backwash) the media.

Note 2 * 4cuft is remarkably close to 3 * 3cuft.
I made a spreadsheet with some permutations based on the datasheet. The last row is the cubic feet of media that I calculate for the 15 GPM and various conditions. Since it is a spreadsheet, I could easily add other conditions. Clearly I am calculating less media than the 8 or 9 already proposed. Maybe I mis-calculated or more likely I am not adding the same margins.

The flow rate spec is in terms of area, not volume. The column height spec has a minimum and an optimum. I am trying height numbers between those two. For minimum of 35% freeboard, the tank must be 1.35 times the media height or more. Less freeboard is permitted by the sheet.

 

[ByteMe]

If you oversize the capacity to get the SFR you need, how often do you*need* to backwash?

 

[Reach4]

If you oversize the capacity to get the SFR you need, how often do you*need* to backwash?

I think I remember reading a week max, but I don't find that at the moment.

Even tho filters are usually sold with timed controllers, I think a demand unit would make sense in this case.

 

[Reach4]

The pump runs steady at 50 PSI without cycling.

My GPM flow as measured with the timed/drawdown/measure/volume method at my pressure tank is less than 15GPM but more than 14GPM. (I checked it 3 times). Piping is 1”

Note that during backwash, the water pressure at the filter should stay at 30 PSI or more. The reason that I bring this up is that if the pump can do 14.5 GPM at 50 PSI, it can do even more at 30 PSI. So don't shy away from a system that needs 15 or even 16 GPM for backwash.

Add a handy boiler drain or other faucet at the output of the filter. It can serve various purposes including being a nice place for you to fill your drinking water jug.

 

[Bannerman]

B-Jack had earlier expressed concern over the removal capacity of the media being adequate for the volume of iron. My calculation was to determine the minimum volume of K-L required to remove the daily iron load. _John_'s capacity calculation confirmed that also as 3,600 / 2995/gal/cuft = 1.2 cu/ft.

In support to _John_'s post, the larger issue is the media volume required to actually maintain full iron removal at 14.5+ GPM throughout the entire day. Also to be considered is the true backwash GPM required and valve's ability to actually provide the flow needed.

As the effective iron removal GPM decreases as the media becomes saturated, a larger unit is needed than that indicated to provide the required GPM. With a modestly oversized unit (in GPM) as _John_ suggested, a daily backwash frequency will help to reduce the possibility of iron breakthrough towards the end of the day.

Since utilizing 3 smaller tanks will share the load between each, concerns over valve flow restrictions and backwash requirements are reduced/eliminated.

As the system is being used only for irrigation, perhaps the backwash discharge could be used for irrigating an area which could tolerate a high amount of iron and where iron staining would not be a problem, although high concentrations of other elements such as chloride may be an issue.

 

[ByteMe]

Not knowing the pricing of these systems, would a dual 13" tank setup be cheaper than a tri smaller tank setup?

 

[Brother Jack]

You can't size for the minimum of the Katalox capacity as you'll get bleed thru near the end of a cycle.

85000 mg /7.47 mg/L= 11,379L treated/cu ft. / 3.8 L/G= 2995 gallons/cu ft. media capacity. (again, you can't use all that and expect to get adequate filter performance).

I personally wouldn't size a unit to have the backwash be the max water your pump can put out. Considering the flow rates, and backwash requirements, and that (as dittohead has pointed out in prior threads) Katalox's backwash requirement is a "best case", I'd lean more towards 3 2 or 2.5 cu. ft. units. If you did a daily backwash you'd never use more than 1/5 of the units "capacity" and you'd have well over the rated flow rates per man. specs. Backwash rates would be 9-11 gpm (which I know is higher than their specs).

I do think 2 14" units would cover you as well, but I personally have a control valve that is similar to what I think you're talking about, and I have my doubts as to how reliable a system setup to backwash at the max the valve was capable of would be.

(I know this post is now redundant...but I spent enough time on the calcs that I wanted to post anyway)

John not redundant at all. I really appreciate your thoughts on this.

 

[Brother Jack]

B-Jack had earlier expressed concern over the removal capacity of the media being adequate for the volume of iron. My calculation was to determine the minimum volume of K-L required to remove the daily iron load. _John_'s capacity calculation confirmed that also as 3,600 / 2995/gal/cuft = 1.2 cu/ft.

In support to _John_'s post, the larger issue is the media volume required to actually maintain full iron removal at 14.5+ GPM throughout the entire day. Also to be considered is the true backwash GPM required and valve's ability to actually provide the flow needed.

As the effective iron removal GPM decreases as the media becomes saturated, a larger unit is needed than that indicated to provide the required GPM. With a modestly oversized unit (in GPM) as _John_ suggested, a daily backwash frequency will help to reduce the possibility of iron breakthrough towards the end of the day.

Since utilizing 3 smaller tanks will share the load between each, concerns over valve flow restrictions and backwash requirements are reduced/eliminated.

As the system is being used only for irrigation, perhaps the backwash discharge could be used for irrigating an area which could tolerate a high amount of iron and where iron staining would not be a problem, although high concentrations of other elements such as chloride may be an issue.

First, thank you for your comments and thoughts on this . RE: backwash discharge....In the area I have the well tank and plumbing and plan to install the filter system...is the same area I used to have my laundry. There is a discharge drain for a laundry pit that is no longer used. It's going to be perfect for the backwash water. It's kind of like a septic pit being a large round concrete box with the holes on the side surrounded by crushed stone. it is probably 3' below ground in soil that is pure sand. 30-40 years from now, the iron will probably find its way back into the well.LOL

 

[Brother Jack]

I am truly humbled at how much help you guys are. I can't believe the great information you are providing. EVERYONE thank you for all of your thoughts so far.....