Saturday, July 25, 2009

Do I need a Iron Filter ???

Nobody likes those unsightly reddish orange stains. They are in the shower, toilets and just about everywhere your water touches. There are a lot of opinions about using a separate piece of equipment to filter out the iron before the water softener, but a water softener can be a great iron/rust remover if set up properly. If your shopping for a new water softener and are unsure if your softener will remove all of the iron/rust in your water, this article should help. First things first, we have to find out if your water is a good candidate for removing iron/rust. There a a few determining factors/rules that you must follow. Your going to have your water test handy to proceed. Don't guess on the iron either. If your not sure, have it tested by a water treatment professional. The amount of iron or rust your water softener can remove is determined by the amount of hardness in your water, and the P.H. of your water. A lot of people don't test for PH and just ignore it, but it's very important. PH runs on a scale of 0-14. 7 is neutral. Any reading above 7 is alkaline and below 7 is acidic. Iron is very easily removed if your PH is below 7. In fact, softeners love to remove iron from acidic water. As long as your not getting blueish green stains on your tub or toilets (this is a sign of the acid water eating or leeching your copper plumbing) don't worry about correcting the PH of your water--despite what someone wants to sell you ! I have treated water with as high as 12-15 ppm of iron with a water softener when the PH is acidic. You just have to use salt with a iron removing additive and regenerate your softener more often. This is a lot easier than having another piece of equipment in your house to maintain--and iron filters can be a pain in the neck ! So here is what you need to do to set up your softener to remove high iron with a acidic PH. (I will get to alkaline PH in a little bit)

1. You must use red out salt (salt with a rust remover additive) in the salt tank. Don't mix between regular and rust out, that won't work. You have to use 100% rust out salt all the time !

2. Your salt setting must be on 15 pounds. This is important. This is the setting for a one cubic foot softener (30,000 grain capacity)(2,000 grains per pound of salt) Consult your owners manual to figure out your salt setting.

3. You must compensate or add in the iron to your hardness. This is called compensated hardness. Take the total amount of iron in your water (parts per million -ppm) and add four (4) grains of hardness for every part per million.

Example: You have 8 ppm of iron in your water. Multiply that by 4. You now have 32 grains of hardness that represent your iron. Add that to the amount of hardness in your water. Now you have a compensated hardness. Here is a sample water analysis:

Hardness: 15 g.p.g (grains per gallon)

Iron: 8 ppm

PH: 6.5

Your compensated hardness is 47 grains per gallon (g.p.g)

Now since your using 15 pounds of salt per regeneration (change that salt setting !) you will get 30,000 grains of capacity. Now divide that 47 into 30,000 and you get the amount of treated gallons you can get between regenerations--which is 638.30 or just 638. Next we need to know how many water users in the house. Each water user in the house represents 80 gallons per day. This is a good figure to base your calculations. So if you have 3 people in your family or house using water on a daily basis, that's 240 gallons per day. Now divide that 638 total treated gallons from you water softener by 240. This comes out to 2.66. This is the number of days your softener can run before needing to regenerate again. I am assuming that you have a timered system that you can set the days of regeneration. I would set this at every 2 days. You can try three, but with large amounts of iron, two would probably be better. Keep in mind that these are the settings for the above water analysis. Yours will probably be different but calculated the same. Whatever your compensated number comes out to, you divide that number into 30,000.

NOTE: If you have bigger that a one cubic foot (30,000) softener, you can set the salt higher to get more capacity. For example, if you have a 45,000 grain softener or 1.5 cubic foot, you can set the salt at 18 pounds which will give you 36,000 grains capacity(2,000 grains per pound of salt)

IMPORTANT: Most Internet sites and dealers refer to one cubic foot softeners as 32,000 grains. This is the amount you will get with brand new resin. Once the softener regenerates, even the first time, you will only get 30,000. The 32,000 is only the capacity for virgin resin. You can achieve 32,000 but you would have to use 22-30 pounds of salt per regeneration to achieve this.

If you have a metered softener or demand softener, it's a little different in how you set the meter. All of the above still applies as far as salt and capacities. First, make sure you have the salt set at 15 lbs. Second, you must have some gallons in reserve. Most metered softeners don't regenerate as soon as the meter hits zero (unless you have a twin-system with two resin tanks) so if the meter runs to zero at 10 am on a Saturday morning, you can have bad water by noon. To avoid this, set a reserve to get you through the day. Deduct 80 gallons per person per day. So if we use the above number of 638 gallons per regeneration and you have 3 people in the house, you have to deduct another 240 gallons and set your meter at 400 gallons. This will insure you won't have bad water before your softener has a chance to regenerate--since most softeners do not regenerate till between 12:00 am and 2:00 am.

IMPORTANT NOTE: If you have a digital metered system, a lot of them will automatically program in a reserve amount. Just make sure to put in the correct amount of compensated hardness (hardness + ppm of iron times 4 = total hardness) Consult your owners manual to find out how it performs.

Iron removal with a PH ABOVE 7.0
If you have a neutral or alkaline PH, iron removal has it's limits and rules to follow also. All of the math for determining gallons and days of regeneration still apply. However, with water in a alkaline state you must have a good hardness to iron ratio to effectively remove the iron in the water. You must have a 4 to 1 hardness to iron ratio. For example, if you have 3.0 ppm of iron, you must have at least 12 gpg of hardness. Iron is not as soluble in an alkaline state and harder to remove. So whatever your iron content of the water with a alkaline PH, multiply the iron by 4. If you have at least that much hardness, the softener will remove it with no problem. Here are some examples:
Hardness: 10 gpg Iron: 5.0 ppm PH: 7.5
A softener will probably not work under these conditions. If you follow the rule, the required amount of hardness in this water analysis is 20 gpg.
Hardness: 28 gpg Iron 3.5 PH: 7.7
In this situation, a softener will work fine for iron removal. The 28 gpg is well above the 14 gpg needed. The higher the hardness, the better the iron removal.
I sure hope this educates you in your decision to buy a water softener or just to set up your softener differently so that it will work properly. If you have any questions or need help with your water. Just send me an email and let me know !
The Water Guy


  1. A really good, informative article. I've never understood the pH relationship before, and I've heard advice to the contrary. Your explanation is clear and it makes sense.

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