Vinyl, Fiberglass or Plaster: Caring for Your Pool's Surface

Applies to: In-ground and above-ground pools with vinyl liners, in-ground fiberglass pools, and plaster, concrete or aggregate finishes. Surface makers' instructions differ; your own manual and warranty come first.

Why surface type changes the routine

Pebble Tec says that owning a pool finish comes with the responsibility of keeping water chemistry right. Latham's fiberglass warranty notes that improper or corrosive water can damage surfaces, equipment and decks.^[1][5]

Hayward's AquaRite manual explains both directions: corrosive water dissolves plaster walls, and over-saturated water causes scaling and staining.^[6]

Makers do not agree on every number. For calcium hardness, River Pools' fiberglass guide says less than 120 ppm, while Latham's fiberglass warranty lists 250–350 ppm. Use the figures from your own pool's maker.^[4][5]

Vinyl liners

• Brush gently. Latham suggests a soft-bristle brush or sponge to keep dirt and undissolved chemicals from building up on the liner.^[3]
• Watch the brush ends. Continental's liner care sheet warns that sharp brush ends can tear a liner, especially in corners and on steps, and recommends a vacuum head designed for vinyl pools.^[7]
• Keep chlorine off the liner. Continental says not to put tablets or sticks in the skimmer, and never to broadcast dry chlorine directly into the pool, because both can bleach the vinyl.^[7]
• Watch chlorine levels. The vinyl liner makers' association (CFFA) says excess chlorine is the most common cause of fading and cites a recommended 1.0–3.0 ppm. CDC's minimums still apply: at least 1 ppm in pools, or at least 2 ppm if you use cyanuric acid (stabilizer).^[2][8]
• Avoid spot bleaching. CFFA links it to undissolved product settling, floating dispensers resting in one spot, and too little brushing after shocking.^[2]
• Clean the waterline gently. Dirt and oils there can stain, so don't use abrasive cleaners, and check with your pool maker before using any chemical on the liner.^[3][7]
• No sharp objects or toys with sharp edges, which can puncture or tear the liner.^[3][7]

Some liner makers tell owners to dissolve chlorine or shock in a bucket first. CDC says to pre-dissolve only when the product label directs it, and then to add the chemical to water. Follow your product label.^[3][9]

Fiberglass pools

River Pools, a fiberglass manufacturer, says calcium is the root cause of most discoloration on fiberglass, and that excess calcium combined with high pH and chlorine can discolor the gel coat.^[4]

• River Pools says to avoid calcium hypochlorite in fiberglass pools and not to add calcium.^[4]
• It recommends a chelating stain, metal and scale control product, and says fiberglass ranges differ from industry standards built around concrete pools.^[4]
• Latham's warranty says its fiberglass pool is designed to stay full of water at all times, and excludes damage from improper draining or rising groundwater.^[5]
• Latham also says to keep runoff water away from the pool, and requires weekly water testing by a pool professional under its warranty.^[5]

Plaster and aggregate finishes: what one finish maker says

Pebble Tec's aggregate finishes are made of pebbles and cement. Its care page recommends regular chemical testing at least once a week and keeping printed test reports in case of a warranty request. That is separate from daily checks: CDC recommends checking chlorine and pH at least twice per day.^[1][10]

• Brush with a nylon brush, which Pebble Tec calls very important, working the walls and floor toward the main drain.^[1]
• Losing a few pebbles during start-up is normal, according to Pebble Tec.^[1]
• Pebble Tec notes that high chlorine can make metals or minerals drop out of the water and cause cloudiness, scale or stains.^[1]
• Pebble Tec says to wait at least 14 days before heating the water of a new finish, and to monitor chemical balance more closely after you turn on the heater.^[1]
• Salt can harm new or unprotected finishes. Pebble Tec says salt left on the surface may scale, stain or discolor it, and Pentair says some salt pellets could damage plaster. Waiting periods before adding salt differ by maker.^[1][6][11]

Pebble Tec asks owners to follow its own instructions where they differ from general advice, since its instructions are specialized to its products. Check what your own finish maker says.^[1]

Stains: identify before you treat

Latham says most vinyl stains are organic or metal. Metal stains often come from ladders or heaters, and waterline rings from undissolved chemicals or calcium. Its advice is to contact the pool maker before using chemicals on a liner.^[3]

When to call a professional