Pebble, Quartz, and Aggregate Pool Finishes: Care, Chemistry, and Longevity

Pebble, quartz, and exposed-aggregate finishes are the premium category of pool interiors. Pebble Tec and its competitors (Pebble Fina, Pebble Sheen, Stone Scapes) are marble-based aggregate with colored pebbles troweled onto the shell. Diamond Brite and Hydrazzo use a similar process with quartz or marble chips. These finishes cost 20–40% more than plain plaster and last 15–20 years instead of 7–10.

How aggregate finishes are applied

The process is similar to a plaster application but with aggregate mixed into the marble-cement base:

1. Shell prep — bond coat troweled onto the gunite.
2. Aggregate finish troweled on at approximately 1/2" thickness.
3. For pebble finishes, surface is acid-washed or pressure-washed after initial set to expose the pebble texture. For quartz/aggregate, the surface is polished smooth.
4. Pool is filled and startup chemistry begins immediately.

Why the pool owner sees them as “low maintenance”

• Texture hides minor stains— small algae spots or light calcium scale are visually masked by the variegated surface.
• Durability— aggregate is harder than plaster and resists the year-to-year spot etching that plain plaster develops.
• Color permanence— aggregate colors are locked in with stone, not pigmented plaster. They don't fade like colored plaster.

The service-tech reality

Aggregate finishes have their own care profile, not just “set and forget.”

• Calcium hardness matters more, not less. The marble cement that holds the pebbles in place dissolves in acidic, calcium-starved water. Keep CH above 250 ppm; keep pH from dipping below 7.2.
• Brushing is different. Soft nylon on pebble works; stiff nylon or metal on exposed aggregate scratches cement matrix and loosens pebbles.
• Pebble loss over time.Even properly maintained pebble finishes shed some pebbles annually — normal wear. Persistent loss over a small area points to localized chemistry issues.
• Scale shows differently.Calcium scale on pebble looks like white film in the cement matrix between pebbles; on plain plaster it's a uniform whitening. Different diagnosis, different treatment.

Startup chemistry — critical for aggregate finishes

The first 28–30 days set the trajectory for a pebble pool's 20-year life. Key moves:

1. No chlorine for the first 48–72 hours. Acid wash or pressure-wash acid residue will drive pH low; chlorine added to low pH is corrosive to the aggregate.
2. Brush twice daily for 14 days. Removes plaster dust before it permanently stains.
3. pH stay 7.2–7.6, never below 7.0. Aggressive LSI is the single biggest threat to aggregate startup.
4. CH stabilize at 300–400 ppm during the first month.
5. Avoid granular chlorine or salt cells for the first 30 days. Concentrated chemistry on the fresh surface etches locally.

Common aggregate brand families

Aggregate pools are one place the extra effort during startup pays back for two decades. A pebble finish that was started badly looks mediocre for the rest of its life. One started well looks like the day it was poured for 10–15 years.