Waterco / Waterway 75ft² / 100ft² Filter Cartridge - AKA Rainbow RTL75

Premium Quality. Trusted Brands. No Gimmicks.

Heater & Spa Parts supplies premium-grade pool and spa cartridge filters. Unless otherwise stated on the individual product listing, our replacement cartridges are supplied by leading filter manufacturers including Magnum® and Darlly®, using high-quality filtration media such as Reemay®, Darlly® media, Pleatco® media or equivalent premium-grade material.

Magnum and Darlly are established specialist cartridge-filter manufacturers supplying replacement and OEM filtration products throughout the pool and spa industry. Major equipment and spa brands generally do not manufacture their own cartridge elements. Instead, cartridges are commonly produced by specialist filtration manufacturers to suit the required housing, dimensions and filtration specifications.

Their products are used across equipment from brands including AstralPool, Balboa, Davey, Emaux, Halo Spas, Hurlcon, Madimack, Oasis Spas, Sapphire Spas, SpaNet, Spa World, Vortex®, Waterco, Zodiac and many others.

Because we purchase filters in significant volumes, we can offer recognised premium filter brands at competitive pricing without relying on cheap, unidentified generic cartridges commonly found through marketplace sellers.

Why filter quality matters

A cartridge filter needs to maintain water flow while trapping fine debris without the media prematurely collapsing, separating or shedding fibres.

• Quality filtration media with consistent pleat construction
• Strong end caps and centre cores
• Better resistance to repeated cleaning cycles
• Reduced risk of premature fibre shedding or media failure
• Reliable filtration without unnecessarily restricting water flow

Cheap cartridges can look almost identical when new, but differences in media quality, pleat construction, bonding and internal support can significantly affect service life and filtration performance.

NSF® and recognised filtration materials

Many premium filtration materials and cartridge ranges from manufacturers such as Darlly®, Magnum®, Pleatco® and Reemay® are manufactured using materials tested or certified to recognised filtration and water-industry standards. Where a specific NSF® certification applies to a product, media or material, this should be considered in conjunction with the manufacturer's specifications for that particular cartridge.

How to clean a cartridge filter

Clean the cartridge when:

• Spas: water flow or jet pressure noticeably reduces.
• Pools: filter pressure rises approximately 35 to 45 kPa above the normal clean-filter pressure, unless the equipment manufacturer specifies otherwise.

Cleaning procedure:

1. Switch the filtration system off and remove the cartridge according to the equipment manufacturer's instructions.
2. Rinse loose debris from between the pleats using a garden hose.
3. Periodically soak the cartridge in a purpose-made cartridge filter cleaning solution to remove oils, lotions and accumulated contamination.
4. Rinse thoroughly after soaking.
5. Reinstall the cartridge carefully and ensure all seals, lids and locking components are correctly seated.

When should a cartridge filter be replaced?

There is no single replacement interval that applies to every pool or spa. Cartridge life depends on water chemistry, operating hours, contamination, cleaning frequency and how heavily the system is used.

As a general guide, many cartridges are replaced approximately every 12 to 24 months, but replacement should be based primarily on condition and performance.

Replace the cartridge if you notice:

• Torn, frayed or separating filter media
• Cracked or damaged end caps
• Collapsed or badly distorted pleats
• Persistent poor flow even after proper cleaning
• Contamination or staining that cannot be removed
• The cartridge no longer returns to normal operating pressure after cleaning

Warranty

Unless otherwise stated, our standard cartridge filters are covered by a 12-month replacement warranty against manufacturing defects in materials or workmanship. Disposable cartridges and filters used in inflatable spas may have different warranty conditions. Damage caused by incorrect installation, misuse, excessive pressure, chemical damage, poor water chemistry or improper cleaning is not considered a manufacturing defect.

Why buy your filter from Heater & Spa Parts?

• Recognised filter manufacturers including Magnum® and Darlly®
• Premium Reemay®, Darlly®, Pleatco® or equivalent filtration media where specified
• Thousands of replacement applications across pool and spa equipment
• Competitive pricing through high-volume purchasing
• Dedicated online Filter Finder to help identify the correct cartridge
• Real pool and spa parts knowledge if you need help identifying an unusual filter

Buy the correct filter once. Match the dimensions, end configuration and cartridge number carefully before ordering, and use our Filter Finder if you are unsure.

How to Measure a Pool or Spa Cartridge Filter

If you do not know the exact filter model or part number, measuring the existing cartridge is usually the easiest way to identify the correct replacement. You will need a few basic measurements, preferably in millimetres (mm).

Measure as accurately as possible, but allow for a small amount of variation between an old cartridge and a new replacement. As a general guide, dimensions within approximately 5% may still indicate the same filter, particularly where an old cartridge or filter body has expanded, compressed or distorted with use.

1. Total length

Measure the main body length of the cartridge. Generally, do not include a handle, locating spigot or threaded connection unless the filter listing specifically requires that measurement.

2. Outside diameter

Measure straight across the widest part of the cartridge. This is the outside diameter of the filter.

3. Hole or spigot diameter

Spigot: If the cartridge has a male locating spigot or male threaded connection, measure the outside diameter of the spigot or thread.

Hole: If the cartridge has an open hole rather than a spigot, measure the inside diameter of the hole.

4. End connection type

The end connection is just as important as the overall dimensions. Common cartridge filter connections include:

• Open hole
• Fine thread
• Coarse thread
• Male spigot
• Camlock or bayonet-style fitting