Instinct Spas Replacement Hot Tub Covers

Instinct is the direct-to-consumer brand of Master Spas of Fort Wayne, Indiana — the owner’s manual for all three models is published by Master Spas, and Master Spas is already in this fitter. The line is deliberately short: three hot tubs, both of its cabinet sizes square, so there are only two answers to give.

Here is how the 3 Instinct models in our fitter map to AIRCAP 1™ sizes:

• The Natural Instinct takes the AIRCAP 1™ XX-Small, which fits square spas 77–79".
• The Vital Instinct and Pure Instinct each take the AIRCAP 1™ Small, which fits square spas 83–85".

The Vital and the Pure are the same size. Both measure 84" x 84" and both take the Small — what separates them is the seating molded into the shell. The Vital is built around a full-size lounge seat; the Pure uses an open seating arrangement. So if you own one of the two 84" Instincts and are not sure which, it does not matter: the cover is the same either way. If you want to settle it anyway, look for the lounger — if one seat lets you lie out flat, it is a Vital; four corner seats around an eight-sided footwell make it a Pure.

Instinct and Master Spas Healthy Living. The Instinct owner’s manuals give the three models their own listing numbers — 9964 for the Natural, 9965 for the Vital and 9966 for the Pure — and the 2025 and 2026 editions print the same sizes. Master Spas’ Healthy Living owner’s manuals print the same footprints under other names and listing numbers: the HL 630L (2015–2021 manuals) and HL 620L (2015–2018) at 78" x 78", the size of the Natural; the HL 7 at 84" x 84" (2015–2021), the size of the Vital; and the HL 7.5 at 84" x 84" (2013–2021), the size of the Pure. In overhead photos each Instinct also shares the seat layout of its Healthy Living counterpart, but the manuals print a different dry weight for every pair, so we call them the same size, not the same tub. Your cover size does not depend on it: all four Healthy Living models are on our Master Spas page at the sizes we give the Instincts — XX-Small for the HL 620L and HL 630L, Small for the HL 7 and HL 7.5.

Master Spas’ Balance models are a second cross-check. Master Spas publishes its own Balance 7 at 84" x 84" and its Balance 6 at 78" x 78", and both are already listed in this fitter — the Balance 7 at Small, the Balance 6 at XX-Small, the same sizes we give the Instincts that share their footprints. The factory replacement cover for an 84" Master Spas cabinet is itself 84" square, which is the clearest confirmation available that the published figure is the outside of the spa and not the acrylic inside it.

Both Instinct sizes also land mid-band rather than on a boundary. At 84" the Vital and Pure sit in the middle of the Small range, and at 78" the Natural sits in the middle of the XX-Small range, so the usual inch of year-to-year variation in a cabinet will not push either one into a different size.

Natural Instinct owners: check your cabinet height. Instinct prints this model as 32" tall on its product page and 34" tall in the owner’s manual. That does not change your cover size — that is decided by the 78" footprint, which both sources agree on — but it does decide which skirt depth you want. Every AIRCAP 1™ ships with the Ziptech™ modular skirt system, so you zip on the depth that matches your cabinet instead of ordering a custom cover; measure the cabinet height as well as the width and you will zip on the right one first time.

Footprints are as published on instinctspas.com and confirmed against the 2025 and 2026 Instinct owner’s manuals, which print the same 84" x 84" and 78" x 78" figures. Cabinet sizes can change between model years, so measure your spa side to side across the top of the cabinet before ordering; the SureFit™ measuring guide walks through it in two measurements. If your measurement falls between two sizes, round up. The AIRCAP 1™ is built for square cabinets from 77 to 94 inches.