Chlorinator and Chemical Feeder Service
Purpose
An erosion chlorinator is a pressurized vessel holding a concentrated oxidizer in the middle of a plumbing loop, and it is serviced by whoever is on the route that day. This procedure guarantees the feeder is opened in a sequence that does not put a face into accumulated gas, is never loaded with a product it did not already hold, sits downstream of the heater behind a working check valve, and is set by measurement rather than by a dial position somebody guessed at. The two events it exists to stop are a lid opened on a feeder that has sat with no flow, and a shop that tops up a trichlor feeder with calcium hypochlorite because that is what was on the truck.
Scope
Covers routine service and repair of pad-mounted chemical feeders on residential and light commercial pools: inline and offline erosion chlorinators, and peristaltic or diaphragm liquid feeders for hypochlorite or acid.
It does not cover salt chlorine generators, which the salt cell SOP owns; manual shock dosing or superchlorination, which the shock dosing SOP owns; bulk acid handling and dilution, which the muriatic acid SOP owns; or how chemicals ride on the truck, which the chemical storage and transport SOP owns. Target chemistry ranges belong to the water chemistry SOP and to your health jurisdiction's code.
Roles and responsibilities
| Role | Owns | Hands off |
|---|---|---|
| Route technician | Product identification, opening sequence, loading, feed-rate setting, all readings | Records the product name from the label and the valve position, so the next tech is not guessing |
| Shop lead | One product per account, feeder replacement decisions, the re-pipe call | Approves any product change in writing and confirms the feeder body was replaced, not cleaned |
| Customer | What they buy and add between visits | Told in writing that only the named product goes in this feeder, and why |
The feeder is a reactor, and its label is the law
Three things about this equipment are not negotiable, and each of them has hurt somebody.
Product identity. Chlorinating tablets and granules are EPA-registered pesticides, and the directions on the container are legally binding: using a product in a manner inconsistent with its labeling is a violation under FIFRA, not a shop preference. Trichlor and calcium hypochlorite react violently with each other and with organics, oil and ammonia. A feeder holds residue, so a feeder is dedicated to one product for its life, and if two have been used in it the body is replaced, not rinsed.
Accumulated gas. A feeder that has sat without flow builds up chlorine gas and pressure in the body. The lid is opened only after the pump has moved water through it, with the feeder's own control valve closed and pressure relieved, slowly, from upwind, with the face out of the plume. Odor is never an all-clear: chlorine deadens the sense of smell at concentrations that still injure, so the release criterion is time upwind in moving air, never a nose. And if the reading or the burn in your throat changes while you are working, you leave the pad rather than finish the task.
Position in the loop. The feeder goes downstream of the heater, with a check valve between them. Concentrated, acidic feeder solution sitting back in a copper heat exchanger destroys it, and the customer's next complaint is the heater, not the feeder. If the plumbing is the other way round, or the check valve does not hold, nothing goes in the feeder until it is corrected.
Trichlor also carries a slower consequence worth stating once: it is acidic and it adds cyanuric acid to the water with every tablet. Cyanuric acid does not evaporate or burn off, so feed rate is capped by cyanuric acid, and past that cap the answer is dilution, never more tablets.
Procedure
Establish what product this feeder holds before your hand goes near the lid. Read it off the container the customer buys, the account record, and the feeder's own label. Accept when one product is identified by name and its label is in front of you. Wrong is deciding from tablet appearance; trichlor and cal hypo tablets can look alike to a tired tech. Stop rule: if two products have been used, or nobody can say, do not open it - flush the body by running the system, keep everyone back from the pad, and replace the feeder body rather than cleaning it.
Run the system, then relieve the feeder and open the lid slowly from upwind. Run the pump at normal flow for at least five minutes, close the feeder's control valve, relieve its pressure at the vent or valve the manufacturer provides, and break the lid seal at arm's length with your face out of the opening and the wind at your back. Accept when the lid lifts with no hiss, no push-back and no visible plume. Wrong is a lid that resists or hisses: back off, re-open the control valve, run the pump longer, and try again. Never lean over the opening, never look into the body, and if your throat or eyes sting at any point, walk upwind and stay there before deciding anything.
Inspect the body, lid gasket, control valve and outlet check valve with the system off. Accept when the body shows no crazing or swelling, the gasket is supple and seats in a clean groove, the control valve moves through its range, and the check valve holds against back pressure. Wrong is a crazed body, which is a replacement and not a repair, or a check valve that passes backwards. Stop rule: a check valve that does not hold means no tablets go in until it is replaced. Wear chemical splash goggles and chemical-resistant gloves for this: residue in the body is the same oxidizer as the tablets and it burns skin wet.
Confirm the feeder sits downstream of the heater with a working check valve between them. Trace the plumbing from the pump through the filter and heater to the feeder and on to the returns. Accept when the feeder outlet is downstream of the heater outlet and a holding check valve sits between. Wrong is a feeder plumbed ahead of the heater, or with no check valve. Stop rule: do not load the feeder, quote the re-pipe, and inspect the heat exchanger for green staining or weeping, because a feeder in the wrong place has probably already been eating it. Hazard: none at this step beyond a wet pad, it is tracing pipe with the system shut down.
Load only the identified product, to the label's directions and within the feeder's rated capacity. Accept when the tablets are the named product, the quantity is inside the feeder's stated capacity, and the lid gasket is seated clean and dry. Wrong is topping up with whatever is on the truck. Broken tablets throw dust, which is an inhalation hazard on the same chemistry as the gas, so load from upwind with goggles and gloves, do not brush dust off with a bare hand, and treat the ingestion route as real: nothing to eat, drink or smoke on the pad, and hands washed before anything else.
On a liquid feeder, service the tube, the injection fitting and the foot valve as one assembly. Check the peristaltic tube for flat spots and cracking, clear the injection fitting and its check valve, confirm the suction foot valve seats, then prime and watch a full stroke cycle. Accept when the pump delivers a visible, steady draw with no drip at any fitting. Wrong is a hardened tube or a crusted injection fitting, both of which let the head lose prime and the account drift chemically for weeks. Never service a hypochlorite line and an acid line with the same uncleaned tools or containers: the two together produce chlorine gas immediately.
Close up, open the control valve, restart the pump, and prove the feeder holds. Accept when the lid is seated to the manufacturer's method, the control valve is at the intended position, and the feeder runs five minutes at full flow with no seepage at the lid, no drip at the check valve and no back-flow toward the heater. Wrong is a lid cross-threaded and forced. This is the step that puts pressure and chemical back into a vessel you just opened: stand to the side of the feeder rather than over it while it comes up to pressure, keep the customer and any pets off the pad, and re-verify the check valve holds now that there is flow behind it.
Set the feed rate against a measurement, and check the cyanuric acid before you increase anything. Test free chlorine and cyanuric acid, move the control valve one increment at a time, and record the valve position with both readings. Accept when free chlorine sits inside the range your health jurisdiction and the water chemistry SOP set for this pool, and cyanuric acid is below the ceiling that code states. Wrong is opening the valve two increments because the pool looked dull. Stop rule: cyanuric acid at or above the code ceiling means the trichlor feed does not go up at all - the correction is partial drain and refill, quantified, and the customer is told that in writing.
The record this produces
One feeder block on the route record, carried forward every visit.
- Product: exact name off the label, and confirmation the feeder is dedicated to it.
- Opening sequence: pump run time before opening, pressure relieved, and any push-back or plume observed.
- Condition: body, lid gasket, control valve, outlet check valve, and the plumbing order relative to the heater.
- Loading: quantity added against the feeder's rated capacity.
- Setting: free chlorine and cyanuric acid readings, valve position before and after, and the direction of the change.
- Escalations: re-pipe quoted, body replaced, or a dilution recommended with its computed volume.
The valve position paired with the two readings is what turns a route into a trend. Without it, every technician starts from zero, and the account oscillates between a green pool and a bleached liner all season.
One feeder service, filled in
A 24,000 gallon residential pool on an inline erosion chlorinator. Complaint: chlorine keeps dropping, and separately, the heater "does not seem as strong as it was."
Step 1: the container in the equipment shed is trichlor, the account record says trichlor, the feeder label says trichlor. One product, dedicated. Step 2: pump run eight minutes, control valve closed, pressure relieved at the valve, lid broken at arm's length from upwind with no hiss and no plume. Step 3: body sound, gasket replaced, control valve free.
Step 4 fails. Tracing the pipe, the feeder discharges UPSTREAM of the heater and there is no check valve between them. The stop rule is taken as written: no tablets loaded. The exchanger is inspected and shows green tracking on two tubes, which is the second complaint explained - the heater has been sitting in concentrated acidic feeder solution every time the pump shut down. The re-pipe is quoted, the exchanger is quoted separately with the chemistry history attached, and the customer is told in writing that the feeder stays empty until the pipe is corrected.
Re-piped the following week: feeder moved downstream of the heater outlet with a check valve between, verified to hold against back pressure.
Steps 5 through 7 then pass: tablets loaded to the label and within the feeder's rated capacity, lid seated, control valve opened, five minute run with no seepage and the check valve holding under flow.
Step 8 is where the account's real problem shows. Free chlorine reads 0.4 ppm, below the range, and the instinct is to open the valve. Cyanuric acid reads 92 ppm, at the ceiling the pool's health jurisdiction sets. So the feed does not go up. The dilution is computed and handed over rather than estimated: to bring 92 ppm down to a 50 ppm target, the fraction of water that has to be replaced is 1 minus 50 divided by 92, which is 0.457, so about 46 percent of 24,000 gallons, roughly 11,000 gallons drained and refilled. Checking it the other way, the 13,000 gallons left behind carry 13,000 times 92 divided by 24,000, about 50 ppm once the pool is full again. The valve stays where it is until the dilution is done, and the follow-up visit re-tests both numbers before a single increment moves.
References
- FIFRA and the EPA-registered product label on the container: label directions for use are legally binding, including loading, dilution and required protection.
- The feeder manufacturer's instructions for opening sequence, rated capacity, lid method and installation position relative to the heater.
- Your state or county health code for pool cyanuric acid ceilings and free chlorine ranges.
- See related: the salt cell inspection SOP; the shock dosing SOP; the muriatic acid handling SOP; the water chemistry out-of-range response SOP for target ranges and corrections.