Inside Information on Chemical Feeders in the Swimming Pool Industry

Today’s modern swimming pools may include one or more of the above pumps. Centrifugal pumps are used for pumping large amounts of water, of particular importance in water recirculation. Piston pumps are of importance in water reclamation, such as reverse osmosis systems. Displacement style pumps or more specifically, reciprocating diaphragm, is a common way to pump chlorine, we know them as automatic chlorinators.

Now we’ve established the importance of pumps in our lives and in particular, the pool industry, allow me to focus in on pumps used for chemical delivery. Although these pumps are properly called displacement pumps (remember) both reciprocating diaphragm, and rotary peristaltic, in the industry, are often called: Chlorinators, chemical feeders, injectors, metering pumps, diaphragm pumps, chem-feeds, and the rotary peristaltic is often referred to as a tube, or squeeze tube pump.

Now that we’ve covered some of the history, I’d like to share some of what I’ve picked up over the years. Working for a well-known chlorinator manufacture for nearly forty-five years has taught me quite a lot. Some of what I have learned may be valuable to you, a pool industry professional. I would like to clear up some myths, or assumptions I’ve been asked about from time to time.

  • Chlorinators should be trouble free. Of all your pool equipment, the chlorinator probable will require the most attention. The reason is simple, you are dealing with more than a mechanical pump, such as; water chemistry, bather load, water temperature, and chlorine. When you put them all together there is more involved than a chlorinator. If any of the above items are neglected your job will soon become more complicated.
  • Chlorine is on its way out. Let’s be honest about this. This is a case where the good definitely outweighs the not so good. Don’t even try to imagine our lives without chlorine as a disinfectant. Alternative forms of disinfectants will continue to play a larger role in our industry, and that is a good thing. Make no mistake chlorine is still the disinfectant of choice in our industry, it simply works well and the cost benefit isn’t worth arguing.

Most pool professionals have their favorite type of chlorine. As a manufacturer, I do too. Let’s go over some selections. Liquid chlorine (sodium Hypo), is usually purchased at your favorite distributor, dealer or chemical company, some regions the chemical is delivered on a route basis. This industrial strength chlorine runs anywhere from 9% to 15% active chlorine. The chlorine you purchase at the supermarket is considerably weaker about 4% chlorine. Sodium hypo, or liquid chlorine is the chemical of choice for most mechanical chlorinators, some will argue that point, but for the most part its liquid chlorine. The problems with liquid chlorine are; it is heavy, cumbersome, and transporting it can be hazardous. Liquid chlorine weakens over time. Dry or powder chlorine also has its advantages, and disadvantages. It is certainly easier to store, and transport. Some kinds also have a built in stabilizer so your Ph rarely needs adjusting, but now you have to be careful of too much accumulation of stabilizer, which will certainly cause eye irritation, etc. Some of the challenges are obvious; you have to mix a slurry so it can be pumped. The amount of undissolved solids will over time foul check valves. Peristaltic pumps are indicated if you choose to pump a chlorine slurry. Peristaltic pumps easily handle chlorine slurries. With either the diaphragm or peristaltic chlorinator, avoid trichlor, this very potent form of chlorine is simply just too corrosive for mechanical feeders and is not recommended.

Some tips on maximizing the performance of your mechanical chlorinator (diaphragm, or peristaltic style)

  • Keep variables to a minimum. Such as, chlorine strength, type of chlorine used, and setting on chlorinator feed rate. Example; if you keep the chlorine strength consistent, as the bather load increases, and the days are warmer, you’ll need to increase the amount of chlorine to be feed. On a peristaltic pump, adjust the on time up (pump longer), with a diaphragm pump increase the cam setting, or pulse rate. If you tamper with chlorine strength (usually a problem with slurries), and chlorinator feed rate, you will just drive yourself crazy. Minimize your variables.
  • Avoid running chemical container dry. Although the pump may not be mechanically harmed, pumping air will cause the valves to build up a residue of dried chlorine (salt), after detailing the check valves several times it should become clear running the chlorinator dry simply creates more work.
  • Purge air out of the pump tubing. After changing out chemical containers make sure, the pump is primed and most air is purged out of the pump head. The system just works better when most of the air (gases) are purged from the lines (eye protection please).
  • Regular maintenance. At least every six months inspect, and if necessary, replace your diaphragm. Also, inspect the top and bottom valves; clean or replace. If you are using a peristaltic feeder, change tubes out regularly. Also keep your eye on the roller assembly; the rollers do require periodic lubrication. Rollers that are frozen, not rolling correctly will dramatically shorten the life of your pump tube.
  • Keep spare liquid ends (assembled pump head kits) handy, as we all know Murphy’s Law, “Problems usually occur at the most inopportune times”, it’s far easier to replace a diaphragm and pump head complete with valves (usually just 4 screws) than detailing every o-ring and ball seat. Using peristaltic pumps? Keep pump tubes and roller assemblies on hand. Time is money.
  • Inspect your foot valve strainer – At least quarterly, or a frequently as necessary.
  • Avoid trying to prime against lyme pressure – Chemical Injectors are easy to prime when the discharge (pressure) line is removed or vented. After the pump is primed re-attach the discharge line to the top pump head valve, or close the vent relief (eye protection cannot be overstated).
  • Always wear eye protection when working on chemical injectors or when changing out containers, or adding chemical.
  • Want to change chemical brands? Avoid changing chemical brands without researching the compatibility on your injector pumps. I know we are pressed for time, this is not the time to cut corners, find out if the new chemical is compatible with your pump before you switch, at least ask a colleague who has had some experience with the product.
  • A flow indicator is a fantastic diagnostic tool – Installed on the suction tubing of your chlorinator (flow indicator) is an outstanding diagnostic tool, at a glance you can see if the pump is working properly. No indication means your chlorinator isn’t pumping. If the ball indicator is bouncing violently it may indicate too much back pressure from a plugged injection fitting. The indicator is simply a window to monitor your system.
  • Chemical controllers are of growing importance to our industry. Most controllers work well with automatic chlorinators; stick with the industry leaders, those with a proven track record. Avoid elaborate so-called turnkey systems that claim to do everything. Caveat emptor.

Robin Gledhill, President
Blue-White Industries
Huntington Beach, CA, USA