diggity
Member
But I'm confused... that's how the softener has been working for over a decade. No pre-treatment. Why would it be bad to go back to that?
Softener. Iron has (almost) defeated me...
- Thread starter diggity
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Looking back at https://terrylove.com/forums/index.php?threads/catalytic-carbon-not-removing-iron.64680/ where you described your system you have that did not work sufficiently:
Well ---> Soda ash injection ---> peroxide injection ---> contact tank ---> Katalox Light filter ---> catalytic carbon filter ---> softener
You said "the contact tank is actually an old 2 cuft calcite neutralizer, which I emptied all the calcite out of. " That would correspond to about 22 gallons roughly (allowing for freeboard above the 2 cuft).
Ditttohead suggested a larger contact tank on that thread. Purpose-built contact tanks are often over 100 gallons. In addition, they have a blowdown/drain port at the bottom to get rid of settled sediment. That would reduce the ferric iron that the next stages would have to deal with.
The atmospheric tank would require a new pump. It would generate noise in the house.
Well ---> Soda ash injection ---> peroxide injection ---> contact tank ---> Katalox Light filter ---> catalytic carbon filter ---> softener
You said "the contact tank is actually an old 2 cuft calcite neutralizer, which I emptied all the calcite out of. " That would correspond to about 22 gallons roughly (allowing for freeboard above the 2 cuft).
Ditttohead suggested a larger contact tank on that thread. Purpose-built contact tanks are often over 100 gallons. In addition, they have a blowdown/drain port at the bottom to get rid of settled sediment. That would reduce the ferric iron that the next stages would have to deal with.
The atmospheric tank would require a new pump. It would generate noise in the house.
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diggity
Member
Good point, maybe my contact tank is indeed undersized. I tried to compensate for that by cranking up the peroxide feed rate. The Stenner pump is already at setting 10, which is as high as it will go. I am diluting the peroxide 1:1. I guess I could feed it undiluted, which would mean that I'd be using about 2 gallons of peroxide per week, but at $10 per gallon, that will get expensive over time.
Regarding the new pump for a possible atmospheric tank, I read a little about the Grundfos MQ pumps. They seem like a nice solution because they don't need a pressure tank. Instant on. Reading the reviews, it sounds like some people have had reliability issues, but maybe an extended warranty would help allay that fear.
Regarding the new pump for a possible atmospheric tank, I read a little about the Grundfos MQ pumps. They seem like a nice solution because they don't need a pressure tank. Instant on. Reading the reviews, it sounds like some people have had reliability issues, but maybe an extended warranty would help allay that fear.
Bannerman
Well-Known Member
If the peroxide, chlorine or other oxidizer doesn't have enough contact time to react with the iron to oxidize it, then you're likely just wasting money no matter how much or how little oxidizer you add.
diggity
Member
Interesting - I may also STILL not be using enough peroxide. I'm reading through the guidance on Stenner's manual: http://www.cleanwaterstore.com/wp-content/uploads/2014/09/Stenner_peroxide_startup.pdf
And borrowing their calculation:
"Example: Assume that you have a well pump that has a flow rate of 12 gallons per minute (12 GPM) and that you want to inject 3.0 ppm of hydrogen peroxide into the water. You have decided to use solution strength of 35,000 ppm or 1 gallon of 7% peroxide to one gallon of purified or at least softened water. There are 1440 minutes in 24 hour period, and the formula will tell you how many gallons of hydrogen peroxide you will use for every 24 hours the well pump runs. Example formula: 12 GPM x 3.0 PPM x 1440 and then divided by 35,000 = 1.48 Gallons Per Day"
Plugging in my own numbers (guesstimating the output of the pump and the iron concentration):
10 GPM x 20 PPM x 1440 and divided by 35,000 = 0.34 gallons of peroxide per day.
Right now, I'm using about a gallon per week, which would be 0.14 gallons per day. So I'm only feeding at half the recommended rate. However, the water is also going through the KL filter too, which should do quite a bit of oxidizing as well, right?
I guess I underestimated the amount of oxidizing power I'd need, and quite possibly underestimated the required contact time too. A month ago I thought peroxide would be the secret sauce, but now I'm not so sure. $80 or more per month is pretty expensive. And I really don't want to use bleach... I'm worried about the toxic byproducts and the smell of it makes me want to wretch. I don't want bleach in my water.
Ho boy... well I guess I'm going to proceed this weekend with putting the softener first. It's the only thing that ever removed a substantial amount of iron without all the fuss and bother. If that turns out to be another bad idea, I can always re-plumb it yet again. I'll also have to take a good hard look at the basement and see if I can find a place to put an atmospheric tank. Fortunately it's a walkout basement (garage under), so I might be able to put a tank down by the garage end, with the idea that if it ever overflows, the water would just run right out the garage.
Thanks for the advice and commiseration everyone. If I ever get this problem solved I'll be sure to let you all know what worked!
And borrowing their calculation:
"Example: Assume that you have a well pump that has a flow rate of 12 gallons per minute (12 GPM) and that you want to inject 3.0 ppm of hydrogen peroxide into the water. You have decided to use solution strength of 35,000 ppm or 1 gallon of 7% peroxide to one gallon of purified or at least softened water. There are 1440 minutes in 24 hour period, and the formula will tell you how many gallons of hydrogen peroxide you will use for every 24 hours the well pump runs. Example formula: 12 GPM x 3.0 PPM x 1440 and then divided by 35,000 = 1.48 Gallons Per Day"
Plugging in my own numbers (guesstimating the output of the pump and the iron concentration):
10 GPM x 20 PPM x 1440 and divided by 35,000 = 0.34 gallons of peroxide per day.
Right now, I'm using about a gallon per week, which would be 0.14 gallons per day. So I'm only feeding at half the recommended rate. However, the water is also going through the KL filter too, which should do quite a bit of oxidizing as well, right?
I guess I underestimated the amount of oxidizing power I'd need, and quite possibly underestimated the required contact time too. A month ago I thought peroxide would be the secret sauce, but now I'm not so sure. $80 or more per month is pretty expensive. And I really don't want to use bleach... I'm worried about the toxic byproducts and the smell of it makes me want to wretch. I don't want bleach in my water.
Ho boy... well I guess I'm going to proceed this weekend with putting the softener first. It's the only thing that ever removed a substantial amount of iron without all the fuss and bother. If that turns out to be another bad idea, I can always re-plumb it yet again. I'll also have to take a good hard look at the basement and see if I can find a place to put an atmospheric tank. Fortunately it's a walkout basement (garage under), so I might be able to put a tank down by the garage end, with the idea that if it ever overflows, the water would just run right out the garage.
Thanks for the advice and commiseration everyone. If I ever get this problem solved I'll be sure to let you all know what worked!
Remember that chlorine is much cheaper. If you tuned things right, there might be very little residual chlorine -- even if you did not use GAC to remove what was left. But the H2O2 is nicer if there is residual.
diggity
Member
Yeah, I know, but I'm so not into chlorine. Besides, isn't peroxide a stronger oxidant than chlorine?
Don't know, but I have seen statements to that effect. http://www.apswater.com/article.asp...itle=Chemical+Requirements+for+Iron+Oxidation says that 0.50 ppm of H2O2 is about like 0.65 ppm of chlorine.
Wonder about maybe using 2 stages: cheap chlorine, followed by H2O2 on the residual. http://www.h2o2.com/industrial/applications.aspx?pid=107& I am not saying that is worthwhile, but it is surprising to read that H2O2 can be used for chlorine removal.
ENIGMA-2
Member
Don't recall if you ever mentioned it, but have you ever considered calling in a local water quality professional? Maybe there's something else going on here?
diggity
Member
Yes, that's actually where we started - by talking to a few local guys. Long story short, both of them shook their heads and weren't interested. They didn't come right out and say that they weren't interested, but when they stopped getting back to me I took the hint.
WellOff
Member
I didn't see any mention of what your well is, how deep, static level etc..
H2O2 is FAR superior to "bleach" for oxidizing. Just look in your Stenner manual and you'll see that in their recommended ppms for treating iron and manganese: I know that for iron they say it's .5ppm H2O2 for 1ppm iron and 1ppm for 1ppm of manganese; at 20ppm of iron you should be looking at about 10ppm of H2O2- I've got 2ppm of iron, I go through about 1 gallon of H2O2 per year! (roughly 100 gallons of water per day)
What is your backwashing interval/frequency?
How often are you flushing your contact tank?
H2O2 is FAR superior to "bleach" for oxidizing. Just look in your Stenner manual and you'll see that in their recommended ppms for treating iron and manganese: I know that for iron they say it's .5ppm H2O2 for 1ppm iron and 1ppm for 1ppm of manganese; at 20ppm of iron you should be looking at about 10ppm of H2O2- I've got 2ppm of iron, I go through about 1 gallon of H2O2 per year! (roughly 100 gallons of water per day)
What is your backwashing interval/frequency?
How often are you flushing your contact tank?
Mikey
Aspiring Old Fart, EE, computer & networking geek
I'm a fan of bleach. It's cheap, readily available, NSF-certified (Clorox brand, anyway) for use in potable water, and its residual is easily removed by a GAC filter. We use 105 gpd, a $3 jug lasts us for months, and there's no hint of chlorine smell in the finished water.
I am surprised at the low H2O2 consumption. I think that a good size contact tank is very important to let such low injection amounts succeed. I also read that colder water and higher pH water need more H2O2 to be effective.
Again, I am surprised at the low levels needed. I use more total bleach than that for my regeneration done every 3 days. My bleach is then rinsed off of the media during the regen.
diggity
Member
WellOff, I think our well is around 150 ft deep. Not sure of the static level. The backwash frequency of the KL and sediment filters are both set to 4 days now. I have never flushed the contact tank - I'm kind of hoping that will never be necessary. I'm hoping any precipitated rust will settle to the bottom and then go up the riser tube and on to the KL and sediment filters for removal.
Everything seems to be working pretty well over the past few weeks. I seem to have hit a law of diminishing returns with the peroxide. If I set the feed rate really low, I end up with around 0.5 - 1 ppm iron at the sinks. If I really crank up the feed rate, the iron reading drifts down maybe a tiny bit, but I still have around 0.5 ppm at the sinks. The extra peroxide doesn't seem to be worth the cost. So I have kept the feed rate pretty low (setting 2 on the Stenner - not sure what that works out to in ppm, but I'm only going through a gallon of peroxide about once every week and a half or two weeks, which isn't bad).
The curious thing is that, while 0.5-1 ppm is right around or over the threshold for staining, we are not actually seeing any staining at the moment. Not sure why that is... I'm wondering if maybe the iron is 100% oxidized, but not 100% removed, and some very small rust particles are getting through. I think the Chemsorb can filter down to 3 microns, so the particles would have to be smaller than that. Maybe rust particles that small don't stain. I dunno. But I guess as long as we don't get staining, I don't really care about the residual 0.5-1 ppm!
Anyway, side note... I was scratching my head for a while because we started getting rusty water in the showers. I tested it and found there was about 3 ppm of iron in the hot water. Turns out the iron wasn't coming from the well at all... the sacrificial anode in our water heater needed to be replaced! As soon as I put a new rod in, the iron disappeared from the hot water again. I'm sure all you guys who work in the field would have known this right away, but it was a wake up call for me as a homeowner to check the anode rod periodically!
Everything seems to be working pretty well over the past few weeks. I seem to have hit a law of diminishing returns with the peroxide. If I set the feed rate really low, I end up with around 0.5 - 1 ppm iron at the sinks. If I really crank up the feed rate, the iron reading drifts down maybe a tiny bit, but I still have around 0.5 ppm at the sinks. The extra peroxide doesn't seem to be worth the cost. So I have kept the feed rate pretty low (setting 2 on the Stenner - not sure what that works out to in ppm, but I'm only going through a gallon of peroxide about once every week and a half or two weeks, which isn't bad).
The curious thing is that, while 0.5-1 ppm is right around or over the threshold for staining, we are not actually seeing any staining at the moment. Not sure why that is... I'm wondering if maybe the iron is 100% oxidized, but not 100% removed, and some very small rust particles are getting through. I think the Chemsorb can filter down to 3 microns, so the particles would have to be smaller than that. Maybe rust particles that small don't stain. I dunno. But I guess as long as we don't get staining, I don't really care about the residual 0.5-1 ppm!
Anyway, side note... I was scratching my head for a while because we started getting rusty water in the showers. I tested it and found there was about 3 ppm of iron in the hot water. Turns out the iron wasn't coming from the well at all... the sacrificial anode in our water heater needed to be replaced! As soon as I put a new rod in, the iron disappeared from the hot water again. I'm sure all you guys who work in the field would have known this right away, but it was a wake up call for me as a homeowner to check the anode rod periodically!
Bannerman
Well-Known Member
What strength are you buying?
Bannerman
Well-Known Member
I doubt your well pump runs non-stop, 24 hours/day. You are using the formula to calculate the oxidant volume consumed per day whereas the formula is using 1440 to represent 24 hours of actual pump run time. Since the 1440 represents the maximum number of minutes a pump could run in a 24 hour period, you could change the 1440 to the number of minutes your pump actually runs each day to more accurately compare the set feed rate vs the quantity you actually use.
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Mikey
Aspiring Old Fart, EE, computer & networking geek
Wow. One of us is doing something wrong. I use Clorox Regular unscented bleach (8.25% NaClO), which comes in 3.78 qt jugs. When my chlorine tank (30 gal) gets low (around 5 gallons), I dump in a jug of Clorox, while filling the tank with softened water -- usually just around 20-25 gallons. A Pulsafeeder pump injects this diluted solution into the pipe feeding the contact tank when the pump is running. This is obviously a poor way to mix, but it's a commonly-used method. I haven't done the math to set the pump, but I monitor the output from the contact tank, and tweak the pump as necessary to maintain about a 2.5ppm free chlorine level. As I said, I have to go through this every 5 or 6 months.
WellOff
Member
Bannerman, I'm using 7%. Again, I did the math EXACTLY as Stenner instructs: I'd say that I'm actually using MORE then they state- I did this because I also have low levels of IRB (which would also place demand). But these are base numbers, what matters is RESIDUAL. As I am getting 1ppm residual (suggested is 0.3ppm to 0.6ppm) my injected quantity is about right on target.
I am not suggesting H2O2 for the diggity's issues. I was just replying to a statement about proportional use of injected quantities of "bleach" or H2O2 as noted by Stenner themselves (PCM SERIES PUMP CONTROL MODULE INSTALLATION AND MAINTENANCE MANUAL IMPCM Rev1012) page 8, section B. states that the Oxidization Rates required for each ppm of H2O2 for Iron is 0.5ppm, for Manganese it's 1.0; for each ppm of Chlorine for Iron it's 1.0ppm, for Manganese it's 2.0ppm.
I was surprised at my initial calcs! But, again, I went with them (after several re-calcs verified my numbers were right) and it's the RESIDUAL that's confirming all of it.
I'm definitely open to any corrections on this (provided it's supported by professional documentation).
I am not suggesting H2O2 for the diggity's issues. I was just replying to a statement about proportional use of injected quantities of "bleach" or H2O2 as noted by Stenner themselves (PCM SERIES PUMP CONTROL MODULE INSTALLATION AND MAINTENANCE MANUAL IMPCM Rev1012) page 8, section B. states that the Oxidization Rates required for each ppm of H2O2 for Iron is 0.5ppm, for Manganese it's 1.0; for each ppm of Chlorine for Iron it's 1.0ppm, for Manganese it's 2.0ppm.
I was surprised at my initial calcs! But, again, I went with them (after several re-calcs verified my numbers were right) and it's the RESIDUAL that's confirming all of it.
I'm definitely open to any corrections on this (provided it's supported by professional documentation).
diggity
Member
I don't know why this never occurred to me before, but maybe the best idea is to simply monitor the peroxide concentration with a test kit. I see several peroxide test kits, including a pack of strips that only cost about twelve bucks...
That way, if you need to carry a residual to the faucet (for pathogen sterilization), then you can monitor for that. Or, if you want to inject just barely enough peroxide to zap the iron without leaving any residual, then you can do that too.
That way, if you need to carry a residual to the faucet (for pathogen sterilization), then you can monitor for that. Or, if you want to inject just barely enough peroxide to zap the iron without leaving any residual, then you can do that too.
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I think the contact time would contribute to determining the target residual needed.
