We are in the market to replace our water softener, and have been advised that our tannin level is very high at over 3 ppm. Since the water is very hard (22 GPG), iron is not detected, pH is 7.1 units, we were told that we need a water softener using tannin resin in addition to the standard resin used for softening.
We have also been advised that we have two options: combine both types of resin in one softener; or purchase two separate “softening” systems – the first to remove iron and hardness, and the second to remove the tannins.
We are in the market to replace our water softener, and have been advised that our tannin level is very high at over 3 ppm. Since the water is very hard (22 GPG), iron is not detected, pH is 7.1 units, we were told that we need a water softener using tannin resin in addition to the standard resin used for softening.
We have also been advised that we have two options: combine both types of resin in one softener; or purchase two separate “softening” systems – the first to remove iron and hardness, and the second to remove the tannins.
What would you recommend? Any advice you can provide would be very much appreciated.
Answer: Basically, a mixed bed option (two types of resins in one softener) is a less expensive option, but not always the preferred route. The reason is because when higher hardness, iron, or manganese levels are present, these can cause deactivation of tannin specific resin, and lead to bed failure. In a mixed bed, the tannin (anion exchange) resin is of lower density when compared to traditional cation (water softening) resin, so the tannin removal resin will always be located on top of the cation resin. A standard softener flow pattern design has the raw (untreated) water passing first down through the resin bed, with treated water exiting out of the distributor tube, and into your home. The problem here is that the raw water first travels through the tannin removal resin, and if higher levels of hardness/iron/manganese are present, this can result is deactivation of the tannin resin over time. If you have lower hardness, iron and manganese, this can be an appropriate solution, but with high levels of theses contaminants, it is a better idea to first place a traditional water softener in advance of a softener that is designed specifically for tannin removal.
One other thing you need to be aware of is that different tannin specific anion exchange resins will work only on specific types of tannins. There are also different type of “tannins” throughout the country, and to correctly treat your specific tannin, you need to select the correct resin for the job. Anion resins that are specific for only one type of tannin are available at lower cost, but if you apply them into the wrong application, the resin you use may not work effectively to correct your problem. The way around this is to use a macroporus type anion exchange resin. The advantage is that this type of resin will removal all types of tannins – the disadvantage is that it is expensive. You can see some of the tannin resins we have available on our Chemicals, Resin & Filter Media page.
Tannin is a difficult material to treat for, and incorporating tannin resin into a system will always add cost, as tannin resin is expensive – be cautious – lower additional cost can mean an insufficient amount of tannin resin is used in the system design. Tannin resin does have a finite lifetime, but exact duration of the resin bed is difficult to predict, as this depends on flow rate, water quality, temperature, and water usage. Generally, you can expect an normal service life of somewhere between 3 to 7 years before you need to replace the resin at a cost of approximately $560.00 (replacement of resin only – not the complete system!).