1. Build quality
Frame material (Stainless steel in the StreamLife swim spas and Olympus; WPS in most PeakLife and CityLife; Impregnated wood in ClassicLine), reinforcement method (Poli-MAX™ or Fiberglass), and acrylic grade. The Wellis 2025 range is dominated by WPS + Poli-MAX for hot tubs, Stainless + Fiberglass for swim spas. Both are well-proven constructions.