Spa Fitter
Evolution Spas Monarch Replacement Cover
The Evolution Spas Monarch takes the AIRCAP 1™ Large — a foam-free replacement hot tub cover for square spas 89"–91". The Monarch's cabinet measures 91" x 91", inside the Large's range. The cover weighs 35–40 lb for life, costs $1,195, is engineered to comply with ASTM F1346-23, and carries a 3-year limited warranty.
| Spa cabinet | 91" x 91" |
|---|---|
| AIRCAP 1™ size | Large fits 89"–91" |
| Cover weight | 35–40 lb — constant for life |
| Price | $1,195, free US shipping |
| Skirt | Ziptech™ modular, three lengths included |
| Safety | Engineered to comply with ASTM F1346-23 |
| Warranty | 3-year limited warranty |
Why the Large fits the Monarch
The AIRCAP 1™ comes in six sizes covering square spas from 77" to 94". Each size is built to overhang its band slightly — that is how a spa cover is meant to sit — so the Large, which fits cabinets 89"–91", covers the Monarch's 91" x 91" shell with the right overhang.
At 91" the Monarch is at the top of the Large's 89"–91" range — the largest cabinet this size covers. Measure before ordering: half an inch more and the cover you need is the X-Large. Within Evolution Spas, the Monarch shares that 91" x 91" cabinet with Centurion, Oxford and Stockbridge — same footprint, same cover. Evolution Spas builds the 9 models we fit on 3 footprints, and the Monarch is on the largest of them; the line spans 3 of the six AIRCAP 1 sizes.
Cabinet dimensions can change between model years. Before ordering, measure your Monarch at its widest point across the top, in both directions, including any acrylic lip that overhangs the cabinet — the SureFit™ guide walks through it in two measurements. If a figure you have found elsewhere is larger than ours, an overhanging lip is the usual reason. If your spa measures between two sizes, round up.
Every spa in our catalogue that measures 91" x 91" is on one page: hot tubs that take a 91" × 91" cover — the same AIRCAP 1™ Large, at the same price.
How the AIRCAP 1™ is built
Instead of a rigid foam core wrapped in vinyl, the AIRCAP 1™ uses welded drop-stitch construction: a sealed air chamber with no foam to absorb water, so it does not become the waterlogged two-person lift that ends most foam covers. More on how it insulates, how it holds up, and why it is foam-free — or estimate what your current foam cover weighs.
Every Evolution Spas model we fit
| Model | Cabinet | AIRCAP 1™ |
|---|---|---|
| Essence | 80" x 80" | X-Small |
| Mirage | 80" x 80" | X-Small |
| West-Port | 80" x 80" | X-Small |
| Highlands | 85" x 85" | Small |
| Reserve | 85" x 85" | Small |
| Centurion | 91" x 91" | Large same cover as the Monarch |
| Monarch (this page) | 91" x 91" | Large |
| Oxford | 91" x 91" | Large same cover as the Monarch |
| Stockbridge | 91" x 91" | Large same cover as the Monarch |
Evolution Spas Monarch cover: common questions
What size hot tub cover fits the Evolution Spas Monarch?
The Evolution Spas Monarch takes the AIRCAP 1 Large, which fits square hot tubs measuring 89"–91" across. The Monarch's cabinet measures 91" x 91", inside that band. Measure your spa side to side across the top of the cabinet to confirm before ordering.
Will the AIRCAP 1 fit an Evolution Spas Monarch?
Yes — the Monarch's 91" x 91" square cabinet falls in the AIRCAP 1 Large's 89"–91" range, and the Ziptech modular skirt system ships with three skirt lengths so the drop over the cabinet adjusts without a custom order. Cabinet sizes can change between model years, so confirm with two quick measurements.
How much does a replacement cover for the Evolution Spas Monarch cost?
The AIRCAP 1 costs $1,195 in every size, including the pump, three Ziptech skirt lengths, and tie-down straps, with free US shipping and 30-day returns. Unlike a foam cover it has no foam core to waterlog, so it stays at its original 35–40 lb weight for life.
How heavy is a replacement cover for the Evolution Spas Monarch?
The AIRCAP 1 Large weighs 35–40 lb and keeps that weight permanently — its sealed drop-stitch air core cannot absorb water. A foam cover starts at 40–75 lb and gains weight as the foam saturates.
Not a Monarch?
The Spa Fitter matches the current models of every major brand to the right AIRCAP 1™ — or measure any square spa with SureFit™.