Underwater Magic

Collection: Underwater Magic

12 products

Underwater Magic Swimming Pool Glue, Adhesive & Sealant

Seal pool tile joints, cracks, and fittings without draining the pool with Underwater Magic — the professional-grade underwater-cure sealant trusted by commercial pool technicians. PST Pool Supplies stocks Underwater Magic in individual 290ml/9.8oz tubes and 12-count cases in five colors — starting from $56.90.

Underwater Magic originated from a formula developed with a German chemist for commercial maritime divers sealing ship leaks underwater — then reformulated since 2009 for chlorinated and saltwater pool environments. Unlike silicone-based pool sealants that require drained, dry surfaces to bond, Underwater Magic is a single-component sealant that cures fully underwater, eliminating the need to drain the pool for sealing work. It maintains permanent elasticity after curing — flexing with normal pool structure movement rather than cracking like rigid epoxy compounds. The formula is engineered specifically for pool chemistry: resistant to chlorine, saltwater, UV exposure, and weathering across a broad temperature range (-40°C to +90°C, with short-term tolerance to +200°C). It contains no silicone, oxime, acetic acid, isocyanate, or solvents, and meets food-proximity safety standards. Available in five colors — White ($59.20), Black ($57.80), Blue ($57.80), Tan ($57.80), and Gray ($56.90) — to match existing pool tile grout, coping, and fitting surrounds for invisible repairs.

Underwater Magic can seal gaps and cracks up to 40mm wide, making it suitable for tile joint resealing, coping joint repair, return fitting and light niche perimeter sealing, skimmer throat sealing, and step edge repairs. It maintains pool clarity during application and does not cloud the water. Repairs can be made while the pool remains open and operational — no downtime required. Important compatibility note: Underwater Magic is not compatible with vinyl pool liners. It is intended for plaster, concrete, tile, and fiberglass pool surfaces and fittings. Case quantities (12ct, $537.80–$553.80) provide the best value for service companies and facilities performing multiple repair projects.

Shop Underwater Magic at PST Pool Supplies and make professional underwater pool repairs without the cost and disruption of draining your pool.

Frequently Asked Questions

Can Underwater Magic really seal a pool fitting without draining the pool?
Yes — Underwater Magic is specifically formulated to cure and bond in direct contact with water, making it genuinely usable for below-waterline repairs without draining. The product is a moisture-cure adhesive: water triggers the curing reaction rather than inhibiting it (which is why standard silicone or epoxy fails underwater). Real-world underwater repair applications include: skimmer faceplate gaskets — the gasket between the skimmer body and the pool shell at the waterline is a common leak point; applying Underwater Magic to reseal the gasket perimeter can stop the leak without draining. Return fitting gaskets — the flat gasket behind a return fitting eyeball in the pool wall can be resealed if accessible. Hairline cracks in plaster — small cracks in gunite plaster that are accessible from inside the pool can be filled while the pool is at normal water level. Loose tiles at or below the waterline — Underwater Magic bonds tile to the substrate underwater. The key limitation: surface preparation still matters — clean the repair area free of algae, biofilm, and loose material for best adhesion. The sealant cannot bridge large structural cracks or replace damaged fittings; it seals gaps and bonds surfaces but is not structural repair for significant damage.
Which Underwater Magic color should I use?
Select the color that most closely matches your pool surface at the repair location: White — for white plaster pools, white grout lines, white PVC fittings, and white fiberglass surfaces. The most commonly used color for most residential gunite and plaster pools. Gray — for gray plaster or quartz aggregate surfaces, gray grout, concrete pool decks, and gray-toned fiberglass. Tan/Beige — for tan-toned pebble finish plaster (Pebble Tec, Pebblebright), beige tile grout, and pools with warm-toned finishes. Black — for dark aggregate plaster surfaces, black grout, or when a dark-color pool finish is present. Also used for black PVC fittings and dark decorative tile. Blue — for blue tile, blue-tinted grout, or pool surfaces with a blue coloration. For fitting and plumbing repairs (PVC skimmer bodies, return fittings), the fitting color (typically white or gray) should guide selection — the sealant visible at the fitting/shell interface will be seen by swimmers. For below-waterline plaster repairs, the exact color match matters less once submerged — water depth and pool lighting change the visible color significantly regardless of which you choose.
How do I apply Underwater Magic for a skimmer gasket repair?
Skimmer faceplate gasket repair with Underwater Magic requires the pool to be at or near normal water level: (1) Identify the leak location — a failing skimmer faceplate gasket typically causes water loss that stops when the water level drops below the skimmer opening. Confirm by plugging the skimmer suction line and watching whether water loss stops. (2) Clean the repair area — use a stiff brush to remove algae, calcium scale, and biofilm from the skimmer faceplate perimeter and the pool shell surface around it while submerged. A clean surface is essential for adhesion. (3) Load the tube into a caulking gun — Underwater Magic 290ml tubes require a standard 290ml (European-format, 10oz-equivalent) caulking gun. Cut the tip to a bead size appropriate for the gap being filled. (4) Apply while submerged — insert the tip into the gap between the skimmer faceplate and the pool shell wall and apply a continuous bead around the perimeter. The water activates curing immediately. (5) Press and hold — use your fingers to press the bead firmly into the joint for 60–90 seconds to ensure contact adhesion. (6) Allow 24 hours before resuming normal pump operation. For above-waterline application (coping, tile repair above water), the application process is identical but the cure time may differ slightly with air exposure.
What pool repairs is Underwater Magic not suitable for?
Underwater Magic has specific limitations that make it inappropriate for certain repair applications: (1) Vinyl pool liners — explicitly not compatible. The adhesive chemistry does not bond to vinyl liner material. For vinyl liner repairs, use a vinyl repair kit (patch with vinyl-compatible adhesive) instead. (2) Large structural cracks — Underwater Magic can fill gaps up to 40mm, but it is not a structural repair material. A crack that is widening due to ongoing soil movement, hydrostatic pressure, or structural failure requires professional gunite patching or structural epoxy injection, not sealant. (3) Active water leaks with flow — if water is actively flowing through a crack or joint (flowing fast enough to be visible), Underwater Magic cannot cure in place; the water movement prevents the bead from setting. The flow must be stopped (hydraulic cement in the void, or drain the area) before applying sealant. (4) Pressure fittings with failed threads — Underwater Magic seals gaps around fittings but cannot replace the structural integrity of a fitting with stripped threads or a cracked body. Replace the fitting before sealing. (5) Surfaces with active efflorescence — concrete that is actively bleeding mineral deposits through hydrostatic pressure will reject the adhesive bond at the surface; the underlying cause must be addressed.