Monthly Archives: May 2008

Backwashing Filter Sizing

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Automatic backwashing filters use coarse media to treat water problems such as iron, taste & odor and even to balance pH. Because these filter media are so coarse, they do not allow for the easy passage of water, thus making the rated flow for filter media in general much less than water softener media which is spherical, smooth and slippery. Often times the flow rate for a given media is lower than the required backwash rate. For example, a 10-inch diameter filter media tank containing activated carbon will provide a flow rate of 3 to 4.5 gallons-per-minute (gpm) but has a backwashing flow requirement of 5gpm. So your water supply will need to have a maximum flow rate of 5gpm to backwash the carbon properly, but when the filter is in operation, your 5gpm flow rate will be restricted to 4gpm.

Yet another consideration is the amount of media to use which directly affects the size of the media tank. If you are removing 2 parts-per-million (ppm or mg/L) of chlorine with your carbon filter, then at least 1.0 cu/ft of granular activated carbon should be used. And if you are a heavy water user with several people in the household, then you may want to consider doubling that capacity. But you will first need to make sure that your water system’s flow rate is high enough to handle the 7gpm backwashing flow rate requirement. The more media you use, the larger the diameter of the media tank. The larger diameter of the media tank, the higher the service flow rate, but again, the higher the backwashing flow rate requirement.

There are some filter media that have as high of a service flow rate as the backwash flow rate, but for the most part, filter media needs a high backwash flow rate. The various filter media and their flow rates in different size media tanks can be found at our Filter Media Flow Rate page. Keep in mind that water pressure and temperature can also affect flow rates.

Softener and Backwashing Filter Control Valve Replacement

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The main component of your water softener or auto-backwashing filter system is the control valve. It initiates and controls the regeneration and/or backwashing of the water treatment media. The media requires regeneration or backwashing to remove any contaminants it was designed to filter out of the water. In the case of softener resin media, the control valve regenerates it by exchanging the hardness ions trapped by the resin with sodium ions and rinses the hardness down the drain. For filter media, the controller backwashes it to remove any trapped particles and to refresh the media bed which prevents water channels from forming. Water channeling would drastically reduce the filter media’s effectiveness.

Over time, control valve components can wear out or break down. While the professional grade controllers we offer are less likely to malfunction, standard consumer style controllers often do fail. Replacing parts on these controllers is usually quite simple, but over time can become economically impractical. This would be a good time to consider replacement of the entire control valve. But before you do, there are some points to consider.

First of all, you should have some experience with water treatment equipment before you begin a project such as this. Either you installed your water softener/filter yourself, or you are an experienced “do-it-yourselfer”. The manufacturers of the Fleck, Autotrol and Clack control valves we carry and support recommend a professionally trained service person do the job. There are other considerations as well. The water’s flow direction on the old controller you are replacing might be opposite of the new controller you are considering. If that is the case, your water pipes will need to be re-plumbed.

Another consideration is the size of the riser tube or “distributor” that runs down the length of the media tank. The majority of the control valves we have available come default with a 1.05-inch diameter opening to accept a 1.05-inch diameter distributor tube, but some older models used to be set up with 13/16-inch distributors. The newer 1.05-inch control valves will not seal properly over those. And the newer Fleck 7000 accepts a 32mm distributor tube which will not work with a standard 1.05-inch distributor without and adapter.

If you purchase a new control valve from us, you will need to know the diameter of your media tank. This information allows the manufacturer to configure the control valve for your softener or filter. Also, control valves come in basically two configurations: softener or filter. Softener control valves can be metered or “on demand” while filter control valve should not. Filter control valves are designed to schedule backwashing over a user-defined period of days rather than the amount of water that flows through the tank like a softener does. There are a few good reasons for this, but the main one is that filter media is of a different consistency than softener media. It needs to be backwashed on a regular basis to avoid water channeling. Some filter control valves also use “brine” injectors while others do not. All softener control valves require a brine injector system.

There are a few nation wide water treatment companies out there that produce tanks and control valves that do not conform to industry standards. For a standard residential water treatment application, the threads on the media tank are 2.5 inches in diameter by 8 threads per inch. All of the residential control valves we carry use these dimensions. Larger commercial controllers are designed for 4-inch tank openings. Some of the national companies will use a different style of thread to prevent industry standard control valves from being used on their equipment. For residential applications, make sure your media tank’s threads are 2.5 by 8.

Removing The Old Control Valve

Hopefully, your water treatment system will have some sort of water bypass system in place, either a bypass valve or a 3-valve shutoff. If not, you will need to shut the water off for the entire house in order to disconnect the control valve from the pipes. Pressure inside the control valve and media tank can be released after the water is shut off or bypassed by manually initiating a regeneration or backwash. See your water treatment systems instruction manual for the proper method. Once water pressure is released from the system, you can disconnect the water pipes and unscrew the control valve from the media tank. Be careful when removing the control valve that you are replacing. The distributor tube that runs up the center of the media tank is held in place with at least one o-ring inside the control valve and there is nothing holding it down inside the media tank except for the media. If this distributor tube is pulled out from the bottom of the media tank, it can prove very difficult to get it back down in there. When lifting the control valve from the top of the media tank, rock it back and forth to help the internal o-ring release the riser tube.

Attaching The New Control Valve

Check the top of the riser tube to ensure there are no cracks or damage which could lead to leaks, then make sure the top of the tank itself is clear of media debris. Even a small particle can prevent the control valve o-ring from sealing properly, resulting in a leak. Place the new control valve over the media tank with the distributor tube centered into the receptacle in the bottom of the  valve. It should slide right in. Then screw the control valve down tight but do not use a wrench or other tool. The control valve’s o-ring will seal very well when it is hand-tightened.
If you purchased the exact same controller you are replacing, then chances are the pipes and drain line will already be set to connect. Otherwise, you may need to use a different drain line fitting and possibly redo your water pipes.

Your control valve will now need setup. If it is an electronic control valve such as the Fleck 7000 or Fleck SE, Autotrol LOGIX or Clack WS-1, you will need to program it for your particular water situation. Softener control valves will need to know how much compensated hardness is in the water for example. You can migrate the settings from your old controller as well. In either case, you will need to refer to the service manual for your control valve for programming or setup instructions.

Because tanks have such a long lifespan, you basically now have a new water treatment system with warranty. Often times this can be achieved at nearly half the cost of a whole new softener and up to 30% less than a whole new backwashing filter system.

Pharmaceuticals And Hormones In Our Water Supply

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A study by The Associated Press has made quite an impact with the general public lately. The report lists prescription drugs and hormones in our water supplies. This comes as no surprise when you consider what is probably flushed down toilets all over the country. A small amount of drugs will not make much of a difference. But in this country, prescription drugs are used by nearly everyone. Just watch the network news for 30 minutes and count how many of the numerous commercials there are for medications. You will be surprised. The human body cannot absorb all of these hormones and drugs completely, so they are passed out through urine and feces. That is how they make it into our water supply.

Water treatment plants are not currently required to test for nor remove these chemicals. Even if they were, the molecular size of some of these drugs and hormones (probably from oral contraceptives) are too small for conventional filtration. Bottled water comes to mind as a temporary solution, but the Safe Drinking Water Act (SDWA) does not require water bottlers to test for these types of pharmaceuticals (Source). Boiling your water will not help any. As a matter of fact, boiling water will concentrate the levels of contaminates in the water. Boiling water is used to kill bacteria, it will not treat these chemicals (Source).
These chemicals are also getting into our food supply because this tainted water is being used for crop irrigation. So even though the amounts of these chemicals are measured in parts-per-billion or even parts-per-trillion, they are not going away. And very minute amounts of hormones can drastically affect your body.

There are efforts underway to create methods for removing these pharmaceuticals from the water (Source). They are similar to desalination, which happens to rely heavily on reverse osmosis (RO). Desalination can be thought of basically as reverse osmosis with much pre-treatment and some post-treatment.

Now more than ever, we need to take better account of the things we are ingesting. Nobody gives a second thought to a restaurant or workplace banning second hand smoke, so why would second hand pharmaceuticals be any less serious? How do we fix this problem? I really do not know. Convincing people to stop taking pharmaceuticals will probably never happen. If I did know of a solution, I would not be sitting here at this small desk. I’d be out somewhere making it happen. Undoubtedly, the solution to the problem will not be easy to implement. But for now, there is reverse osmosis available to anyone with very little investment. I have found RO systems for as little at $149 at the local home improvement stores. We have a 4-stage system for $168 shipped free along with some more high performance models to choose from.

The main point is, it doesn’t matter where you get an RO system, it’s just best to get one. It certainly does not hurt to make your cooking, coffee, tea or soft drink taste better which is what reverse osmosis does. My favorite uses for RO water are my morning coffee and a glass of water flavored with Propel for the rest of the day. Propel does not have the artificial sweeteners in it, but there are plenty of those brands out there. They make the water taste great without the syrupy texture of sodas or “sports drinks”. And there’s nothing wrong with a plain glass of water when it’s been through the RO treatment. Even your freezer’s ice maker can be connected to it.