Water treatment issues - Iron removal using Greensand, Carbon and Ion Resin

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Mike Water

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Would very much appreciate some feedback on some well water treatment issues.

We have a whole home treatment system consisting of 1) small plastic sediment filter 2) large standing stainless filter containing both activated carbon (top) combined with Manganese Greensand (bottom) in one unit 3) large stainless filter containing Ion Resin. Then treated water tank and pressure pump.

I’m not certain the advice we have received is correct, particularly in combining the activated carbon and Manganese Greensand in one filter. We have a problem with occasionally having very black water seem be flushed out, particularly after power outages when the pressure pump tank is completely emptied. This black contaminate seems to accumulate in there and possibly pipes as well. It looks like little bits floating in the water in such a concentration that it is very black, it is gone after running the water for 1-2 minutes. Placed in a container it completely settles down to the bottom. I suspect this is activated carbon residue caused by the softer act carbon being broken up by the harder Greensand.

We’ve had a water test. Our Iron level in the water is 0.51 mg/l, I understand that is above standard (0.3mg/l), but I see posts from others with much higher iron content and wonder the Ion Resin water softener would be effective in treating this on its own. Our water pH is 7.1.

I’m considering taking out the Manganese and just using Act Carbon in one stainless filter and Ion Resin in the second, and relying on the resin to eliminate the Iron content. Another reason for taking out the Manganese is that we are not regenerating it, just regular back flowing (we do regenerate the Ion Resin with salt).

Would that work? Am I likely to get staining at that Iron level if we are using the softener?

Thank you very much for any advice you can give!

Mike
 

Reach4

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We have a problem with occasionally having very black water seem be flushed out, particularly after power outages when the pressure pump tank is completely emptied. This black contaminate seems to accumulate in there and possibly pipes as well.
Periodically, turn off the pump, and drain the pressure tank using the spigot at the base of the pressure tank. This is to get rid of stuff accumulating there.

Regarding the rest of your system, I suggest that you post a photo. That will let people picture your system configuration and sizes.

It looks like little bits floating in the water in such a concentration that it is very black, it is gone after running the water for 1-2 minutes. Placed in a container it completely settles down to the bottom.
How long does the black stuff take to settle in the container.

I suspect this is activated carbon residue caused by the softer act carbon being broken up by the harder Greensand.
Are the GAC and greensand separated, or mixed into a tank?

How long did the system work properly after installation?
 

Mike Water

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Periodically, turn off the pump, and drain the pressure tank using the spigot at the base of the pressure tank. This is to get rid of stuff accumulating there.

Regarding the rest of your system, I suggest that you post a photo. That will let people picture your system configuration and sizes.

I don't have a photo at the moment. The main filters are 19L stainless steel standing units that you can load any filter material into through the top, there are manual levers to control flow & backflow.

How long does the black stuff take to settle in the container.

This only happens periodically, I'd have to test again when it happens, it stays suspended for a bit, I guess minutes for it to settle out.

Are the GAC and greensand separated, or mixed into a tank?

No, they are not separated. That is a key concern. In searching I have seen a post or two advising against this. And we are not regenerating the Greensand so I don't know if it is having any effect.

How long did the system work properly after installation?

Difficult to answer because this occurs only periodically. We replace the material annually. These episodes occur most after power outages and after the system is turned off for a while when we are away.
 

Mike Water

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Sorry, not very good with this, my answers are mixed in with the questions in the prior post. Thanks very much for your help!
 

Reach4

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These episodes occur most after power outages and after the system is turned off for a while when we are away.
That seems to say that the system works well when it is regenerated regularly. After a power outage or a shutdown, how about triggering an immediate regeneration upon return?
 

Mike Water

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That seems to say that the system works well when it is regenerated regularly. After a power outage or a shutdown, how about triggering an immediate regeneration upon return?

I do flush the out the pump periodically and at times when I think there could be a problem. The problem is this stuff accumulates not in the filters but throughout the rest of the system, tank, pump & plumbing. It could come flushing out at any time and at inopportune times. We get plenty of power outages.

We backflow the filters very regularly, but I do not regenerate the greensand. It is combined with the carbon so it would not be possible, and I do not have the chemical or procedure for doing so. I do regenerate the ion resin with salt.

The system works fine except for this problem. The main question I have is, is the greensand actually doing anything? Is it serving a purpose if it is not being regenerated? Is the Resin sufficient to eliminate what appears to be a modest iron content (and actually doing so effectively now if the greensand is not working)? My guess at that this point is that the problem is caused by the hard greensand breaking up the activated carbon prematurely during aggressive backwashing and then the broken carbon leaks into the system. I'm leaning toward taking the greensand out and just using activated carbon in the first filter and resin in the second, reasoning that the greensand may not be doing anything aside from creating this issue. If I eliminate the greensand, I just would like to have confidence that the resin should be able to remove the iron.

Thanks again!
 

ditttohead

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When the pressure tank is allowed to completely empty any accumulation can be loosened as the rubber tends to stretch when the tank is empty of water. Unlike a RO tank bladder that basically does not stretch, the pressure tank bladders are smaller are designed very differently. Your description is a little confusing, or "not normal"... can you describe your layout better and post a couple pictures?

Typically a well pump to a pressure tank with 60/40 or similar switch, then water treatment.

As to the GAC/Greensand blend, I have not tested this combo and would never really recommend it without extensive testing but after reviewing each medias specifications I believe the two medias will separate in the mineral tank with the GAC on top. This should not negatively affect the carbon but since I have not actually tested it I cant say for sure. Manganese greensand is typically used with either constant or intermittent regeneration, it is usually not used without a regenerant.
Once we get more information we can be a little more help.
 

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Regardless of the other considerations, I would add a Pentek Big Blue 20 x 4.5 filter housing after your stuff that you suspect is producing stuff. You might put a Pentek DGD-5005-20 or DGD-2501-20 filter cartridge in.

That will both keep crud out of your plumbing and serve to let you know what is coming out of your filter system.
 

ditttohead

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The Pentek is excellent, the only other BB filter I that has passed our testing is the Atlas Filtri. We distribute both, so far I am very impressed with the AF, they are a few dollars more but the quality is exceptional!

Be sure to incorpoarate some type of bypass around the filters so that you can take them offline should a housing crack, an o-ring leak etc. Check out our new stainless bypass, these were designed for restaurant applications where inspectors like to see stainless steel.

https://view.publitas.com/impact-water-products/2018-catalog-final/page/116-117

https://view.publitas.com/impact-water-products/2018-catalog-final/page/198-199
 

Mike Water

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The Pentek is excellent, the only other BB filter I that has passed our testing is the Atlas Filtri. We distribute both, so far I am very impressed with the AF, they are a few dollars more but the quality is exceptional!

Be sure to incorpoarate some type of bypass around the filters so that you can take them offline should a housing crack, an o-ring leak etc. Check out our new stainless bypass, these were designed for restaurant applications where inspectors like to see stainless steel.

https://view.publitas.com/impact-water-products/2018-catalog-final/page/116-117

https://view.publitas.com/impact-water-products/2018-catalog-final/page/198-199
When the pressure tank is allowed to completely empty any accumulation can be loosened as the rubber tends to stretch when the tank is empty of water. Unlike a RO tank bladder that basically does not stretch, the pressure tank bladders are smaller are designed very differently. Your description is a little confusing, or "not normal"... can you describe your layout better and post a couple pictures?

Typically a well pump to a pressure tank with 60/40 or similar switch, then water treatment.

As to the GAC/Greensand blend, I have not tested this combo and would never really recommend it without extensive testing but after reviewing each medias specifications I believe the two medias will separate in the mineral tank with the GAC on top. This should not negatively affect the carbon but since I have not actually tested it I cant say for sure. Manganese greensand is typically used with either constant or intermittent regeneration, it is usually not used without a regenerant.
Once we get more information we can be a little more help.


It's in a confined area so hard to photograph, the photo here shows the filters. The system has a pump from the well pumping into the sediment filter and then these standing filters as described, then to a large PVC holding tank, then the pump providing pressure to the house. There is no pressure tank.

I suppose I can look at putting another final sediment filter after these filters. But also like to optimize the way I am running the existing elements of the system. If greensand requires regeneration, is it fair to say that when used like this (combined with the GAC and not regenerated) that it is not working and can be eliminated with no effect on water quality produced? If that is the case I could go with just GAC in that filter and eliminate 1 potential cause of this problem.

Should filtration with ion resin be sufficient to treat an iron content of 0.5mg/L with a pH of 7.1? If so that will give me added confidence that the greensand is not necessary.

Thank you so much for your advice and opinions!
 

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ditttohead

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How are you measuring capacity for the softening tank? You can use it for iron reduction but it will need regular regeneration. The old manual systems are rarely used here in the US anymore. I see them pop up occasionally and usually just for marketing purposes. The vast majority of the equipment here is automated. Stainless tanks are also rarely used. We stock them but they are epoxy lined so the argument of "no plastic" really doesn't work either. GAC and Stainless don't mix to well.

How often do you clean the atmospheric storage tank? Is there any accumulation in there?
 

LLigetfa

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It's an automatic pump with self-contained pressure tank.
Is this pump after the treatment? Is there any protection to keep it from drawing negative pressure (partial vacuum) that could damage the equipment?
Edit: after reading some more, it looks like it draws from a storage tank that is open to the atmosphere, so should not be an issue.
 
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Mike Water

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How are you measuring capacity for the softening tank? You can use it for iron reduction but it will need regular regeneration. The old manual systems are rarely used here in the US anymore. I see them pop up occasionally and usually just for marketing purposes. The vast majority of the equipment here is automated. Stainless tanks are also rarely used. We stock them but they are epoxy lined so the argument of "no plastic" really doesn't work either. GAC and Stainless don't mix to well.

How often do you clean the atmospheric storage tank? Is there any accumulation in there?

It's rated as 19L, which I believe refers to the recommended amount of filter material, total size including water would be quite a bit larger. I regenerate the resin with salt once a month. The tanks have a special treatment inside, not certain what that is.

I regularly chlorinate and flush the storage tank. It's in an inconvenient location, we scrub it out as much as possible, there can be some accumulation there.

I take it then that if the resin is regenerated that it should be able to eliminate the 0.5mg/L of iron that is present in our water? Meaning the greensand would not be necessary?
 
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ditttohead

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19L of resin or < 3/4 ft3, regenerated monthly? That tiny amount of resin would only give you a short run with even low levels of hardness. What is your GPG hardness level? How many people in the house?

Depending on how you regenerate that system is likely only good for about 18,000 Grains, but iron compensation will reduce that even more. A greensand/carbon system of that size is also way to small for flow rates in excess of 1-2 GPM.

When using softening resin to reduce iron it is important to regenerate frequently. Iron binds to the resin and if allowed to stay it tends to lock on and can be very difficult to remove.
 

Mike Water

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19L of resin or < 3/4 ft3, regenerated monthly? That tiny amount of resin would only give you a short run with even low levels of hardness. What is your GPG hardness level? How many people in the house?

Depending on how you regenerate that system is likely only good for about 18,000 Grains, but iron compensation will reduce that even more. A greensand/carbon system of that size is also way to small for flow rates in excess of 1-2 GPM.

When using softening resin to reduce iron it is important to regenerate frequently. Iron binds to the resin and if allowed to stay it tends to lock on and can be very difficult to remove.

The hardness is 237 mg/l @ CaCO3, pH 7.1, 2 people in the house. Sorry, what is Grains, is that Gallons? Don't think I have flow rates, GPM-Gallon/min?

Is 0.5mg/L a substantial amount of iron? What regeneration procedure or schedule would you recommend with the filters I have and these iron and hardness figures?
 

ditttohead

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Without having exact numbers and a complete water test I can only give you an educated guess.
Your system under normal circumstances should be regenerated no less than weekly. We use a bit more water than average in the US even with our ultra low water use fixtures/toilets/showers etc. The average household water use in the USA is about 50-75 gallons of water per person per day.
 
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