Chemical feeders allow homeowners and service technicians to take more of a hands-off approach to sanitizing water by loading the feeder up periodically, rather than daily.

However, if they aren’t installed correctly, they can actually do harm to the system.

Here, veteran builders and technicians offer tips for avoiding some of the most common mistakes they see in the field.

1. Properly position the injection fittings

With dry-chemical feeders, the goal is to pull water from a place in the system where the highest flow occurs. This helps the chemical dissolve properly before treated water is sent back to the pool or spa. Recognizing this goal, many professionals divert the water immediately after it goes through the pump. But this isn’t as advantageous as it seems, since the unfiltered water can send dirt and debris into the feeder. It’s a better idea to place the first injection fitting immediately following the filter. This spot affords the rapid flow needed to dissolve the chemical, but the water will be clean and free of materials that can plug up the feeder.

2. Inject the chemical in the right place

Where placement of the first fitting is important to the feeder’s effectiveness, properly positioning the second can help protect the equipment. While this belongs in a Chemical Feeders 101 class, it is still cited by service technicians as the area where most mistakes are made.

The second fitting is where the diluted chemical enters the pool’s bloodstream, so to speak. If that chemical solution goes to the wrong place, it can do damage. For this reason, veterans place it at the very end of the equipment line, so that the chemically treated water enters the plumbing just before it returns to the pool or spa. This prevents corrosion in heaters or other devices.

3. Don't forget the (right) check valve

Protecting the circulation-system components from corrosive chemicals involves more than the proper placement of the feeder. The installer also should place a check valve between the heater and the point where the treated water is introduced to insure that none of the diluted chemical solution can migrate backward and cause damage to the heat exchanger. Ideally, internal check valves within the feeder will block chlorinated water from entering once the pump shuts off, but some veteran technicians install an outer check valve as a back-up.

If opting for an outer check valve, professionals should select one that is chemical-resistant and place it properly. As an additional safeguard, some veterans make use of gravity and install a plumbing fixture resembling a Hartford loop between the heater and the chemically treated water. With this concept, the pipe goes through the check valve, forms an upside-down U, then runs to the chemical feeder. With this configuration in place, gravity will hold the door closed on the check valve, and the just-treated water will stay on its side of the loop, since it likely can’t travel uphill to the top of the upside-down U and over.

4. Sample from the right spot

On the more sophisticated chemical feeders that have controllers incorporated into them, sample water must be diverted to sensors, which will read the level of sanitizer, pH and other key parameters. As with the diversions meant for a basic erosion feeder, the fittings should be placed such that there’s enough of a pressure differential between water leaving the system and that going back. This helps push the water along.

Because of this similarity, many installers will place the controller fittings the same way as they would for an erosion feeder, with many using the filter, since it has higher pressure on the influent side than the effluent. But this isn’t an appropriate place to obtain a sample: The unfiltered water will send dirt and oils through the probe chamber, causing it to clog.

Instead, use the heater to provide the pressure differential — divert the water before the heater and send water back after. In the absence of a heater, pull water later in the system, with enough distance between the fittings to create the needed pressure differential.

5. Calibrate and clean sensors

In California especially, automated chemical feeders are becoming more prevalent in commercial pools and spas. Recently, state health codes were changed to require the sophisticated systems on non-residential installations.

As technicians acquaint themselves with automated feeders, they also should make it a routine to calibrate and clean the sensors used to monitor the water’s condition. Some instructions say to do this once a week. This will help insure accurate readings.

6. Seal the chlorine on liquid feeders

For the safety of those in the area, the buckets on peristaltic-pump type feeders should always have lids on them to prevent unwanted items from being dropped inside or chemical from getting out. This is especially true in earthquake-prone areas, where the lids should be strapped down as an added precaution.

7. Don’t oversize peristaltic pump feeders

Sometimes it can be tempting to purchase the largest peristaltic-pump feeder available. However, if the feeder is too big for the pool or spa and injects too much chemical, many professionals are forced to dilute the chlorine in the bucket so that a weaker solution is used.

But when the water and chlorine mix, salt will drop out of the solution and fall to the bottom of the bucket. As the tubing takes in the solids, it could become clogged where it meets the injection fitting.

Professionals should avoid this problem by properly sizing the feeder. When technicians inherit an oversized peristaltic pump, it’s best to place the suction tube so the end is suspected 2 to 3 inches from the bottom of the bucket. This way, none of the salt gets pulled up. It should be noted that this will require cleaning the buckets out every couple of months.

8. Remove the chemical when shutting down or winterizing

When a pool or spa is winterized or shut down for an extended period of time, some technicians and homeowners leave the remaining chlorine tablets in an erosion feeder. But doing so can cause long-term problems.

Once the tablets have been wet, a catalyst effect is activated, and the chlorine will off-gas in the system until it is exhausted. This has been known to cause serious, and expensive, damage to any metal that’s nearby, including heat exchangers, stainless steel clamps, connections and mechanical seals on pumps.

Special thanks to the following individuals for their valuable assistance: Tony Caciolo, Monogram Custo Pools, Coopersburg

Pa. Bob Foutz, Purity Pool Service, Huntington Beach, Calif.

Ben Honadel, Pools by Ben, Santa Clarita, Calif.

Michael Orr, executive director of FPSIE, Sacramento

Ed Penfield, Aqua Island Technologies, Bellingham, Wash.

Guy Wood, Westside Pools in Fort Worth, Texas.