Proper Hot Tub Filter Cleaning & Maintenance

Proper Hot Tub Filter Cleaning & Maintenance

You won’t see Hot Tub Filter Cleaning and Maintenance on anyone’s bucket list, but it’s one of the most important “must-do’s” for hot tub owners.

This task isn’t nearly as bad as most people would have you believe, but it can be if you don’t clean and maintain your filter in a regular basis.

You can’t have a healthy, safe and enjoyable hot tub experience without a filter, so it’s in your best interest to find out the most cost effective, least time consuming and easiest way to keep your filter clean.

Why Do Hot Tubs Need Filters?

• Filters protect your hot tub equipment from harsh or damaging particles in the water that can clog your system or damage your system’s components. Well maintained filters catch nasty particles before they do clog or damage your system.

• Filters also collect bacteria that goes unseen to the human eye. This creates a safer, cleaner and healthier environment for you, your friends and your family to soak in. Why worry about the dangers of pathogens in your hot tub water if you don’t have to.

• You’ll spend a lot less time picking debris, leaves and unwanted additions out of your hot tub if you maintain your filter on a regular basis.

• Not maintaining your hot tub filter may actually void the hot tub manufacturer’s warranty. That alone makes checking and cleaning your hot tub filter at least once or twice a month and replacing your filter every 6 months or once a year at the very least.

Quick Cleaning Vs. Deep Cleaning

Quick Filter Cleanings are easy, entail little or no chemicals and should be done regularly. The easiest method is to simply remove the filter, rinse it down well with a hose, let it dry and then put it back in the hot tub.

For a better, longer lasting clean, use an instant cartridge cleaner or a Water Wand Filter Cleaner.  You can spray most cartridge cleaners right on the filter, let it soak for a short period of time and then rinse it off with a hose.

The Water Wand Filter Cleaner, pictured on the right, is the worlds first hand-held cartridge filter cleaner. It is highly effective at cleaning all hot tub pleated filter cartridges in significantly less time and uses less water than traditional filter cleaning methods.

Deep Cleaning takes several hours, can be done overnight and should be done about every 6 months. Unlike Quick Cleaning, deep cleaning requires the use of a filter cleaning chemicals. The most common deep cleaning method is soaking your filter in a diluted solution of water and filter cleaning chemicals overnight in a bucket.

The bucket must be large enough so that your filter will be entirely submerged in the solution. For the best results, follow the manufacturer’s instructions and let your filter soak overnight. Remove the filter in the morning, rinse if off thoroughly with a garden hose and let it dry off completely before putting it back in your hot tub.

Basic Filter Maintenance Schedule:

• Quick Cleaning Once Every Two Weeks
• Deep Filter Cleaning Once Every 2-3 Months
• Filter Replacement Every 12 Months

If you have any questions or need further details about hot tub cleaning or maintenance, please call Roberts Hot Tubs toll-free at 1-800-735-5290 or email us at and one of our customer care representatives will be happy to help you.

Hot Tub Pump Troubleshooting Guide

Hot Tub Pump Troubleshooting Guide

Please Note – The information contained in this article is provided as a courtesy to our customers and online subscribers.  Any use of the information contained in this article is AT YOUR OWN RISK!



Pumps – The Heart of Your Hot Tub System

When it comes to hot tub systems, no piece of equipment works harder or is depended on more than your pump.

Pumps are responsible for water circulation throughout your tub and the entire system. Pumps draw water from the hot tub and pushes it through the heater and filter and back out through the jets.

This is just one part of a multi-step process to rid the water of impurities before it’s sent back to the hot tub. Most pumps also have a strainer or leaf trap that catches small debris that makes it through the skimmer or main drain.  Pumps capture the debris which eases the burden placed on the filter and leaves it free to catch other pollutants in the water.

The best way to keep your hot tub water clean is to keep it circulating and today’s modern pumps and equipment automates the process to such an extent that it requires very little time and attention from hot tub and spa owners.

Simply program the system to automatically turn the pump on for a set amount of time each day long enough to filter your water thoroughly. That’s all there is to it!

Self-Priming Pumps – Most pumps are self-priming centrifugal pumps. These pumps have a vacuum chamber, commonly known as a pump housing. The pump housing must be filled with water in order for any pump to create a vacuum, resulting in your pump pulling the water out of your spa.

The pump housing will remain full of water while the pump is on and will remain partially full of water when the pump is shut off.  When you turn on the pump the motor will begin to rotate on high speed, even if you have a dual speed pump.

The motor drives the pump impeller, located inside the pumps center portion at the opposite end away from the electrical switch portion of the motor.

While the motor is rotating, the tips of the impeller are sealed hydraulically inside of the pump diffuser, this allows self-priming to occur.

Your pump must have a diffuser in order for self-priming to take place. Some pumps have separate diffusers, while others have the diffuser molded into the pumps cover.
Self-priming pumps are very dependable and simple in design.

They require a sufficient supply of water from the hot tub with no air in the suction lines. Air can get into the lines in a variety of ways.  It could come from a loose strainer cover, a leaky valve, a pin hole in the suction line, a crack in your pipes or loose piping connections.

Your pump should be kept free of dirt and located in an area that’s protected from flooding during heavy rain fall. Very few pumps are successfully repaired once the pump motor becomes flooded.

Why Hot Tub Temperatures Max Out at 104 Degrees

Many people question why their spa will only heat to 104 ºF. Throughout history public bathing was done at higher temperatures. Even today, in Japan, many public bath houses have water up to 115 ºF.

Hot tubs & spas in the United States, Canada and most parts of the world have been regulated to obtain a maximum temperature of 104 ºF since 1980. On Dec 31, 1979, the Consumer Products Safety Commission, CSPC, released advisory #79-071.

The advisory warned that heat strokes could be caused by water temperatures of 106 °F or higher. The CSPC recommended a maximum temperature of 104°F for both public and private hot tubs and spas.

The advisory was adopted by Underwriters Laboratory (UL) and lists it in their controlling document (#UL 1563) for home spas, equipment assemblies and associated equipment. The relevant portion of this document as it pertains to max temp regulations for home tubs and spas is section 32; Temperature Regulating Controls…

32.1 – A unit shall be provided with a water temperature regulating control that has a maximum set point of 40 °C (104 °F) in the tub.

32.2 – The temperature regulating control shall be adjustable and shall have marked settings, but it shall not have any settings marked hotter than 40 °C (104 °F).

32.3 – A digital temperature regulating control that displays the selected temperature, but no higher than 40 °C (104 °F), may additionally display the actual temperature of the water.

UL has strongly advised that any hot tub or spa manufacturer that produces a control, or modifies a standard control, to exceed 104 °F is in violation of their UL listing and can have their listing pulled by UL.

The actual 1980 CSPC cover letter that accompanied advisory #79-071 is listed below:

U.S. Consumer Product Safety Commission Warns of Hot Tub Temperatures
Release # 79-071
December 31, 1979

WASHINGTON, D.C. (December 31, 1979) — Safety officials frequently warn the public about the dangers of drinking and driving. Now the U.S. Consumer Product Safety Commission is cautioning that drinking and hot tubing do not mix well either.

According to CPSC staffers, the use of hot tubs at water temperatures above the normal body temperatures can cause drowsiness which may lead to unconsciousness and subsequently result in drowning.

The risk of drowning is significantly heightened if individuals consume alcoholic beverages while, or prior to, soaking in hot water, CPSC staff warns. The Commission has been informed of 10 deaths recorded so far in 1979, three of which involved alcohol-related drowning in hot tubs heated to approximately 110 degrees Fahrenheit.

Even if no alcohol is consumed, extremely hot water during hot tub use can threaten life, CPSC reports. Soaking in a hot tub with water heated to 106 degrees Fahrenheit, for example, can raise human body temperature to the point of heat stroke (or impairment of the body’s ability to regulate its internal temperature). These conditions can be fatal even to fully healthy adults.

Hot tub sales in the U.S. have increased about 125 percent in the past two years, from approximately 40,000 tubs sold in 1977 to approximately 90,000 sold this year. Based on industry projections, CPSC estimates that sales could climb as high as 135,000 tubs next year, a 50 per cent increase over 1979 sales.

As hot tubs have gained in popularity throughout the nation, so have concerns at CPSC that consumers learn how to use these products safely. Accordingly, CPSC staff strongly urges consumers to observe the following safety rules for hot tub use.

Safety Rules For Hot Tubs

  • Hot tub water temperatures should never exceed 104 degrees Fahrenheit. A temperature of 100 degrees is considered safe for a healthy adult. Special caution is suggested for young children.
  • Excessive drinking during hot tub use can cause drowsiness which could lead to unconsciousness and subsequently result in drowning.
  • Pregnant women beware! Soaking in water above 102 degrees Fahrenheit can cause fetal damage during the first three months of pregnancy (resulting in the birth of a brain damaged or deformed child). Pregnant women should stick to the 100-degree maximum rule.
  • Before entering the hot tub, users should check the water temperature with an accurate thermometer; hot tub thermostats may err in in regulating water temperatures by as much as four degrees.
  • Persons with medical history of heart disease, circulatory problems, and diabetes or blood pressure problems should obtain their physician’s advice before using hot tubs.
  • Persons taking medications which induce drowsiness, such as tranquilizers, anti-histamines or anti-coagulants, should not use hot tubs.

CPSC staff currently is working with staff from the Spa and Tub Association ( a division of the National Swimming Pool Institute) and the International Spa and Tub Institute (both of Santa Ana, California) as they develop voluntary safety standards for the manufacture, installation, and use of hot tubs. These standards, which are expected to reflect many of the above safety warnings, may take effect as soon as spring, 1980.



Filter Cartridge Cleaning Process

Cleaning Instructions for Unicel Spa Filter Cartridges

Filter Cartridge Cleaning Process

1.    Remove the cartridge from the filter housing following the manufacturer’s instructions.

2.    Use a garden hose with a straight flow nozzle to wash down the filter element. Work from the bottom down, holding the nozzle at a 45-degree angle, and wash all the pleats with emphasis between pleats.

3.    Rinse until all dirt and debris is gone.

4.    For all spa cartridges and elements used in swimming pools where perspiration, suntan lotions, and other oils are present, soak the element for at least one hour (over night is most effective) in (1) a filter cleaner; or (2) one cup tri-sodium phosphate (tsp.) to five gallons of water.

5.    Rinse the cartridge again to remove oils and cleaning solution.

6.    If the filter has a coating of algae, calcium carbonate (residue from the calcium hypochlorite), iron or other minerals, soak the cartridge in a solution of one part muriatic acid to twenty parts water until all bubbling stops.

*WARNING: failure to remove all oils and cleaning solution before acid soaking will result in a permanent restriction of water flow and cause premature cartridge failure.

7.    Rinse the cartridge clean and reassemble housing.

Please Note: Unicel does not recommend the use of diatomaceous earth (DE) with cartridge filters. DE particles can become trapped in the body of the media and shorten cartridge life. If desired, a cellulose fiber (synthetic DE) can be used in moderation.

Baquacil as a Sanitizer

If you use baquacil as a sanitizer, the filter element must be cleaned with Baqua Clean before any cleaner is used.

Unlike chlorine, which oxidizes the bacteria in the water, the active ingredient in Baquacil, polyhexamethylene biqunaide or PHMB, destroys the bacterial cells. PHMB locates and binds to the bacterial surfaces, and then attacks the outer bacterial wall.

Once this wall has been compromised, the inner cell membrane, or cytoplasm membrane, is destroyed. This destruction allows the cell contents to disperse into their surroundings where they are further broken down into their elemental parts by Baqua Shock, a non-chlorine oxidizer.

In addition, Baquacil is a mild coagulant, which combines bacterial cells and other small particles in the environment into particles large enough to be trapped by the filter.

The resulting deposit is a gray sticky film on the media, which can only be removed with Baqua Clean. If trisodium phosphate (TSP) or any TSP type cleaner is used prior to stripping the film, the cleaner and the gray film will combine to form a gum-like substance.

Once this occurs, the substance cannot be removed from the media and the filter cartridge must be replaced.

WARNING: Follow all manufacturers’ instructions, warnings and precautions when using Baquacil, Baqua Shocks and/or Baqua Clean.

Hot Tub Equipment Location & Layout

Hot tub and equipment layout

The equipment included in our standard Hot Tub system will take up an area that’s approximately 4’ Long by 2’ Wide.  If you add a gas heater, then your footprint can increase to 5’ long by 3’ wide.  If there are walls or an enclosure around the equipment, then the footprint could increase to accommodate aspects of the equipment and its accessibility and venting.


The Hot tub equipment can be located just about anywhere as long as you comply with local and national Code requirements. National safety codes require the equipment is minimally 6’ away from the tub.  The equipment can’t be closer to the tub unless separated by a permanent barrier.  Local codes vary and it is your responsibility to find out and comply with whatever the local code mandates.  The vast majority prefer to locate the equipment further away than 6’.


Ultimately where and how far away to locate the equipment from you hot tub is up to you but taking the following factors into consideration will greatly enhance your overall Hot Tub experience.


  • If tub and equipment are further than 6’ away from each other, the 1.5” PVC plumbing should be upsized to 2” PVC. If the distance is greater than 50’, the pump and PVC plumbing may need to be upsized again, to ensure pump performance and jet pressure are appropriate.
  • If the gas heater is more than 5’ below the water line, you may need to have a flow switch installed to keep the heater from operating when the pumps turns off.
  • If your pump is located above the water line of the hot tub, it can lose its prime causing water recirculation to stop and result in damage to the pump. Please let us know so we can ensure we can provide you the corrected special fittings to ensure losing prime will not happen.
  • If the equipment is more than 20’ away from the tub, insulating the PVC plumbing will help reduce heat loss through the pipe.
  • Gas heaters require certain combustible clearances above and around them to ensure proper safe operation and access for maintenance. If indoors, the heater may also need additional Kits for exhaust and air intake.  Please let us know if this applies to your application so we can help ensure you have the correct information and Kits for your project.
  • The filter requires minimum vertical clearance above it to allow for removal of the filter element for maintenance. Please let us know in advance if this is a problem so we can provide you with options for smaller or shorter filters requiring less vertical clearances.


Images of equipment and layout

Below are some pictures of different equipment and layout using electric or gas heating systems with related dimensions to help you lay out the equipment for your application.  How your equipment lays out is ultimately up to you, but please don’t forget that all equipment needs occasional maintenance or repairs which will take less time and expense if access to do so is easier.


Layout #1 – ACC controller with 5.5kW electric heater, Topside control, Pentair pump & 75 sqft filter, ionizer and Ball (Blue handle) or Slice (T handle) valves.  Dimensions:  4’L x 2’W x 3’H


Layout #2 – ACC controller with Gas Heater, Topside control, pump, filter, ionizer and Ball (Blue handle) or Slice (T handle) valves.

Dimensions:  4’L x 4’W x 3’H

Layout #2.1

Dimensions:  8’L x 2’W x 3’H


Layout #3ECO Tub System below – ACC controller with 5.5kW electric heater, Topside control, Rhtubs pump, 50 sqft filter, ionizer and Ball (Blue handle) or Slice (T handle) valves.


Dimensions:  42”L x 18”W x 24”H

Hot Tub Ionizers

Hot Tub Ionizers

Nobody enjoys soaking in a dirty or unhealthy hot tub and owners go to great lengths to ensure an enjoyable and relaxing soaking experience in water that’s as clean, safe and healthy as possible.

How do we get our tub and spa water as clean and safe as possible? Simple, by adding chemical sanitizers, pH balancers, oxidizers, clarifiers, calcium boosters, metal removers, water softeners, enzymes and algaecides etc…

If you’re tired of trying to relax in a tub full of chemicals and want to drastically reduce your use of costly chemicals by 80% – 90%, then the Hot Tub Ionizer is the system for you.

In all cases, Ionization is safer and more forgiving than typical chemical treatments.  Ionizers provide softer, gentler water and a more comfortable environment.

It’s much less expensive than chemical treatments and it will increase the life expectancy of everything around the hot tub. That includes bathing suits, pumps, filters, heaters and the rest of your spa equipment.

The Hot Tub Ionizer will save you time and money every year as well as provide you with the following benefits:


• Low Initial Cost
• Superior Water Quality
• Reduces Chemical Use by 80-90 %.
• Lifetime Warranty
• Adds Years of Life to Spa Covers & Equipment
• Reduced Maintenance
• No More Algae Problems
• No More Red Itchy Eyes
• No More Dried Out Skin
• Simple to Install & Operate
• Weatherproofed for Outdoor Installation

How Do Ionizers Work?

Ionizers use a natural water purification process called electrolysis. It starts with an ultra-low voltage charge running through a sacrificial mineral electrode installed in the return line.

This direct current causes the release of copper and zinc ions into the flow of water which aids in the destruction of algae, bacteria, viruses and mold.

To maintain clean, clear, safe and healthy water all you need to do is add a small amount of chlorine or non chlorine shock to your hot tub after each use to kill any organic material in your hot tub.

Why try to relax in a tub full of harsh expensive chemicals when a soothing hot spring-like hot tub experience is just an Ionizer away!

What’s So Different About Our Hot Tub Ionizer?

Our electrodes are custom made from a copper and zinc alloy specifically designed for water treatment. They are four times larger than most spa ionizers, so our electrodes last longer and the replacement electrodes are a better value.

What About Passive Cartridge Ionizers like Nature 2?

You should not use cartridge ionizers. Not only are they very expensive and need to be replaced every few months, you also have little or no control as to the amount of ionization being produced.

Cartridge Ionizers are sold without test kits so you never know what the ion level is or if it’s safe to reduce the sanitizer level. Hands down, the best and most cost effective method of ionizing a hot tub is with an electronic ionizer.

Please note that all hot tub ionizers are created equally. Beware of copper only ionizers with electrodes and a control box that may look like our Hot Tub Ionizer, but are nothing more than cheap knock-offs made from outdated electronics.

Features of our Hot Tub Ionizer include:

• Treats up to 1,200 Gallons
• Adjustable Output for Precise Metering of Ion Production.
• IP66 Rated Weatherproof Controller Protects Electronics from Moisture, Corrosion, and Harsh Environments.
• High Efficiency UL, CSA, and CE listed Auto Ranging (120 or 240 volt) Switching Power Supply which provides 5 volts DC to the controller (must be wired to the pump timer so it has power only when the pump is running.)
• Solid State Electronic Circuitry with Automatic Sequential Polarity Switching to keep Electrodes Clean and Even Wearing.
• Light Emitting Diodes Display Power, Cell Power, and Polarity.
• Has Threaded Electrode Cell with a 2″ Tee Fitting, Sealed Electrical Connections so there are No Corrosion Problems, and 1-1/2″ Reducing Bushings if Needed.
• Lifetime Warranty.


• INPUT VOLTAGE: 120 or 240 Volts AC.
• INPUT FREQUENCY: 50 to 60 Hertz
• CONTROLLER: Plastic Weather Proof
• FLOW RATE: 10 To 120 GPM
• CELL: 2″ Tee with Extention and 2″Threaded Fitting
• CELL REPLACEMENT: 2″ Threaded Male Fitting
• ELECTRODE SIZE AND TYPE: 1-1/2″ Half Round x 2-1/2″ LONG – COPPER & ZINC
• CAPACITY: UP TO 1,200 Gallons

Hot Tub Ionizer Operation

1. Turn on the Hot Tub pump.
2. Test the Hot Tub water and make sure the water is properly balanced and sanitized. Test the water with the copper test kit to see if there is copper already present. If copper is already present it may be from a copper based algaecide or from a previous pH problem.
3. Turn the controller output to MAX. The power light and the cell power light should come on. The cell power light will change color from red to green every few minutes to indicate the cleaning circuit is operating properly. Turning the control down towards MIN decreases the voltage and current to the cell. The Cell Power light will dim slightly as the control is turned down.
4. Now you can stop using heavy sanitizer levels! All you need to do is maintain a constant chlorine level as low as 0.2 pp. It has been proven that maintaining 0.2 ppm chlorine and 0.2 ppm copper is more effective sanitation than using just chlorine at 2.0 ppm.
5. Test the copper level at least once a week until you have found the proper setting for your spa. Now you should only need to test the copper level once or twice a month because the copper level does not dissipate like sanitizers.
6. Do not over ionize your spa. When the level reaches 0.3 ppm turn the control down and adjust as necessary to maintain 0.3 ppm. If the copper level reaches 0.5 ppm turn the ionizer to MIN until the level drops to 0.3 ppm. Maintain the pH at 7.2 to 7.6. Failure to maintain your pH could result in staining if the pH is allowed to drift above 8.0.

Hot Tub Ionizer Installation

1. Before installing the Ionizer the Hot Tub should be clean, pH balanced, sanitized and the filter cleaned.
2. Turn off the power to the spa equipment.
3. Install the cell after the hot tub heater if possible. The electrode cell must be at the bottom or side so that no air will be trapped in the cell. Cut a section of pipe out where the electrode cell will be installed. Glue the TEE in place using PVC glue making sure it is oriented so no air will be trapped in the cell.
4. Mount the Controller on a vertical surface at least 5 ft from the Hot Tub. Fasten with the 4 #6 x 3/4′ screws provided, so that the cord to the cell and the power cord will reach. It is best to install the controller where it is protected from the sun and weather.
5. Wire the ionizer controller into the same circuit as the low speed of the pump (some spa controllers have a circuit designated for “ozone”, which can also be used).  If connected to 120 volts the brown wire is the hot wire, the blue wire is the neutral wire, and the green wire is the ground. If connected to 240 volts the brown and blue are the hot wires and the green is the ground. The ionizer controller automatically adjusts to the incoming voltage.

Ozone vs. Ultra Violet Light Hot Tub Sanitizing

The comparison chart below breaks down the features and benefits of Ozone versus UV technology for hot tub and spa water sanitation and purification.

The upfront cost is about the same for Ozone and UV, but the minimal maintenance and reduced chemical requirements of an ozone system create significant benefits. On the other hand, UV lamps must be replaced every 3 to 12 months and must be figured into the maintenance costs for these systems.