Description
This filter set contains everything needed to replace all six filters in MasterSpas 21-foot swim spas. These models feature two separate filtration zones -- a swim spa zone requiring one MA-R4 and three MA40 filters, and a hot tub zone requiring one MA-R4 and one MA40. Buying them together ensures your entire filtration system is replaced on the same schedule, keeping your water clean and your spa running at peak performance.
Each MA-R4 is designed to accept one EcoPur® Charge Mineral Cartridge inside its filter core, combining mechanical filtration with mineral purification across both zones. EcoPur® cartridges are sold separately.
Compatible Models — Current Generation (2025+)
H2X Swim Spas: Trainer 21D, Trainer 19D Max (2026+), Challenger 21D
Important Note for Pre-2025 Spas
Most MasterSpas swim spas manufactured before 2025 used a female port that accepted a male-threaded filter. Beginning in 2025, that relationship flipped. All filters in this set have a female thread designed for the new male port configuration. If your spa was manufactured before 2025, you may need a thread adapter for compatibility. If you know you need one, it is available for purchase separately on our site. If you are unsure, contact us before ordering and we will confirm the right fit for your specific model and year.
Replacement Schedule
Replace all filters every 12 months under normal use, or every 6 months with heavier use. If you use the EcoPur® Charge Cartridges, replace each one every 6 months.
Due to the nature of filtration products, we cannot accept returns on opened or incorrectly ordered items. Please verify your model and production year before purchasing.
