Manganese Greensand for Iron Removal

[sixn3is7]

First things first, AWESOME Website and Forum! Excellent job, lots of info, Thank you! And thanks for the Pool Calculator! AWESOME!
Did I already say AWESOME?

Wife and I just purchased a house with an inground pool near Pensacola, FL :-D . ~28,000 gallon.
Long story short, CYA = 140 so I am going to drain about 3/4 of the pool . I want to use lawn sprinkler/well water to save some money . Wellwater TA and CH are fine but iron is around 3ppm :x .

Because I am who I am, I had to inspect all the equipment and decided to replace my "cat poop" looking sand. Thats when I came up with an idea :idea: . The sand filter calls fall 225Lbs of #20 silica. My thought was to lay down 75Lbs of #20, 50Lbs of Manganese Greensand and then another 75-100Lbs of #20. Example product http://www.caitechnologies.com/images/PDFs/specs/manggreens.pdf

items that I have already considered;
If Mesh and Grit size are not closely aligned partial media loss is likely over time .
Requires a potassium permanganate (PP) soak and then a backwash every X# of gallons pumped depending on media capacity.

Items that I still have questions about;
Flow rate is too high for media . Will media still function but at a slower rate? (I think so)
Greensand is rated to reduce iron, manganese and hydrogen sulfide but will the media remove "Friendlies?
Will PP have any effect or impact on the silica? (I don't think so but figured I would ask)
Assuming satisfactory iron reduction, PP soaks/backwashes should become much less frequent dependant upon the amount of replenishment water. Would you agree or do you think the Media will suffer degredation due to infrequent PP soak/backwash?

Any suggestions on a separation/barrior between the layers so that if I determine the media must be removed I don't have to dump a lot of sand? I was thinking something like felt.


I have searched all over the forum and the net and have not found any examples or someone discussing such an idea so I would like to know what the people on this forum think. If you think I am crazy or off kilter (my 6 year old thinks so) please let me know.

 

[teapot]

It's an interesting idea, looking at the situation initially the fine particle size would mean looking for a taller filter so the bed could expand without loss during backwash. The stated (max) capacity for iron removal is 1ppm/cubic ft so as a minimum you would require 3 cubic ft which would be 255lb's before the addition of gravel and or filter sand. The small particle size and low flow rate required may mean using a different pump which together with the filter may be more expensive than filling with tap water (faucet). The potassium permanganate has the potential to stain too.

 

[susa]

perhaps there are companies near pensacola/gulf breeze who specialize in renting filtration tanks that can be suited to varying water quality conditions. when my pool was completed I paid a company that dropped off huge tanks (think acetylene gas cylinders for welding..) which I hooked up to water supply and water came out very very blue from the outset. in testing this ultrafiltered water it was absolutely free of all minerals.

had the option of using my own well water also but elected to go with municipal supply as there is a program to rebate a portion of the water used for swimming pool refill. check with your local water utility.

it is possible to manage your pool with high CYA until summer rains return. difficult, but can be done.

 

[sixn3is7]

The stated (max) capacity for iron removal is 1ppm/cubic ft so as a minimum you would require 3 cubic ft which would be 255lb's before the addition of gravel and or filter sand.

You would not need the 3 cuft of media. 1 cuft removes 1ppm/10,000 Gallons before regeneration so 1/2 cuft can remove .5ppm in 10,000 Gal or 1ppm in 5,000 Gal. Working backwards for a 28,000 gallon pool would require 6 backwashes. 28,800 / 5,000 = 6

My other idea is to install a secondary Greensand filter as in the attached picture, using a garden hose to baskwash. Cost is about $100-$150 including Greensand and Potasium Permanganate. This way it could be switched in and out as needed.

 

[susa]

>> secondary Greensand filte....Cost is about $100-$150

if you're prepared to spend that on new equipment, wouldn't it be cheaper to pay for municipal water, especially since you won't need the full 28k? the sewer portion of your water bill should be a rebate line item if you call your local water utility. has been the case in all places I've lived in florida.

 

[bk406]

wouldn't it be cheaper to pay for municipal water, especially since you won't need the full 28k? .

Thats what i think. What are your water rates?
I bought a disposable green sand filter (Metal Trap) to use when i top off the pool in the summer. My town water has around 1.5 ppm iron during the summer and I found the filter I bought reduces the level to around .5 to .75 ppm, so about half.

The green sand idea in the sand filter is interesting, but I have a feeling there would be some difficulties.

 

[sixn3is7]

the sewer portion of your water bill should be a rebate line item if you call your local water utility. has been the case in all places I've lived in florida.

Thank you for the insight . I just called them and all I have to do is write them a letter. Current rate is $2.70/1K & $4.02 for sewer which puts me around $75 for a complete fill.

I am still undecided and very interested in peoples thoughts on either idea and any potential long term benifits.

Other media that I am considering is http://www.caitechnologies.com/images/PDFs/specs/pyrolox.pdf

 

[teapot]

The stated (max) capacity for iron removal is 1ppm/cubic ft so as a minimum you would require 3 cubic ft which would be 255lb's before the addition of gravel and or filter sand.

You would not need the 3 cuft of media. 1 cuft removes 1ppm/10,000 Gallons before regeneration so 1/2 cuft can remove .5ppm in 10,000 Gal or 1ppm in 5,000 Gal. Working backwards for a 28,000 gallon pool would require 6 backwashes. 28,800 / 5,000 = 6

My other idea is to install a secondary Greensand filter as in the attached picture, using a garden hose to baskwash. Cost is about $100-$150 including Greensand and Potasium Permanganate. This way it could be switched in and out as needed.

If it works at 100% as the marketing say it does and they all tell the truth...............Then it has to regenerate 100%, not that it matters if you had to backwash a bit more than 6.
Back wash with a garden hose, how big is your garden hose, not that big I'll bet.
$100-$150 vs $75 for a municiple fill, let me think...................

 

[sixn3is7]

Back wash with a garden hose, how big is your garden hose, not that big I'll bet.

Not for backwashing the whole sand filter only the secondary Greensand filter.

I have previously used Greensand for removal of FE and H2S from home well water and the media usually functions as advertised. You get 7-10 years out of a greensand bed but the Potasium Permanganate is expensive and a pain. Up until last night I had never heard of Pyrolox and I think it would be the better choice. Biggest problem with the whole idea are the high flow rates of the pool equipment compared to lower flow rates for well equipment/city water

But now I feel like a fool because I retested my water and my iron is not what I rememberd. I remembered 3ppm but when I retested it is .3ppm

Lawn City
PH 6.8 7.2
TA 40 30
CH 40 30
FC 0 1.25
FE 0.3 0
TDS 204 42

As I look at the numbers, I have talked myslef out of using the well water.

Maybe someone else who doesn't have access to city water may find this post usefull and decide to pursue the idea.

 

[teapot]

Don't feel bad it was an interesting post and idea.

 

[sixn3is7]

No bad feelings. I hope others will consider the idea and it may lead to a new process for those without city water. You never know.