What Paint to Use on a Pool, Baptistry or Fuel Tank Instead of Floor Epoxy

Use a coating made and rated for continuous immersion: a pool paint for a pool or baptistry, and a fuel-rated tank repair or lining product (or a replacement tank) for a fuel tank. EpoxyPro sells floor coatings for concrete, and we do not carry pool paint, baptistry coatings or tank linings. People often reach for floor epoxy because it is tough on a garage floor and it seems like it should hold up anywhere. Under water or fuel it fails, and the result is usually a coating that blisters, bubbles and peels within months. A church baptistry coated with a general epoxy paint that peeled after three months is a typical example.

Why floor epoxy fails under water

A floor coating is designed for a surface that is wet sometimes and dry most of the time. Our base coat and topcoats are formulated to bond to prepared concrete, take foot and vehicle traffic, shed spills and get mopped. They are not formulated to sit submerged day after day.

When a floor coating stays under water, a few things happen:

• Water works its way into and behind the film. Over time it collects at the bond line and pushes the coating up in blisters.
• Moisture comes from behind as well. A pool shell or concrete baptistry is surrounded by soil or wet structure, so water vapor pushes outward against the coating from the back side.
• Pool chemicals attack it. Chlorine and other treatment chemicals at constant exposure break down coatings that were never tested for them.
• Fill and drain cycles add stress. A baptistry that is filled, heated and drained repeatedly expands and contracts the coating far more than a floor ever sees.

Once blistering starts, the coating cannot be patched back into a sound film. It has to come off.

Pools: use a pool paint matched to what is already there

For an in-ground pool, buy a paint sold specifically as pool paint from a pool supply company. The main types are epoxy pool paint, chlorinated rubber and water-based acrylic pool paint. They are not interchangeable over each other, so the first job is figuring out what is on the pool now.

• Identify the existing coating. A pool supplier can usually tell you with a simple solvent test on a paint chip. New paint generally has to match the old type or the old coating has to be removed.
• Follow the pool paint maker's prep and cure schedule. Pool paints have their own rules for drain time, surface dryness, cure time before filling and water chemistry at startup. Those numbers come from the pool paint, not from anything we sell.
• Plaster, pebble and fiberglass pools are often refinished with their own materials rather than painted. A pool contractor can tell you which applies.

Where our products do fit is the deck around the pool. That is a horizontal concrete surface that gets wet and dries out, which is what a floor coating is built for. See our guide on outdoor epoxy for patios and pool decks for how to coat it.

Baptistries: treat it like a small pool

A baptistry is an immersion vessel, so it needs an immersion coating. Most are concrete, fiberglass or a prefabricated shell, and the right product depends on which one you have.

• Concrete baptistries are usually coated with a pool paint. The same rule applies as with a pool: identify what is on it now and use a compatible product.
• Fiberglass baptistries are typically refinished with a gelcoat or a coating the shell manufacturer approves. Ask the manufacturer before painting anything over it.
• Failed coating must come off first. If a previous epoxy paint has bubbled and peeled, every loose and blistered area has to be removed down to a sound surface. Painting over a failing coating traps the problem underneath.

The floor of the baptistry room, the steps leading in and any surrounding concrete that only sees splashes are a different story. Those are floors, and a properly installed floor coating handles occasional water. Our guide to epoxy flooring in bathrooms and showers covers how we approach wet-area floors.

Fuel tanks: fix or replace the tank, do not paint it

A leaking fuel tank, such as a 250-gallon heating oil or diesel tank, is a containment problem. A floor coating brushed onto a tank will not seal a leak that is under the pressure of the fuel inside, and the solvents in fuel can soften coatings that are not rated for them.

• Stop the leak safely first. Get the fuel transferred out by a fuel supplier or tank service company.
• Talk to a tank professional about repair versus replacement. Tank repair kits and interior linings exist, made and rated specifically for fuel contact. In many cases, replacement is the answer for a corroded tank.
• Check local rules. Fuel leaks and tank replacements can fall under local fire code and environmental rules, and spilled fuel in soil or on concrete may need to be reported and cleaned up.

If fuel has soaked into a concrete floor under the tank, that floor will need to be cleaned and degreased before any coating will bond to it. For a tank room, shop or containment area where the floor sees fuel and chemical spills, a chemical-resistant floor system is worth considering. Our article on novolac epoxy for chemical resistance explains when that is the right choice. That is still a floor coating for spills that get cleaned up, and it does not replace a tank or a lining.

What our coatings are built for

Every system we sell is meant to go on a prepared, horizontal concrete floor: garages, basements, shops, commercial floors, patios and pool decks. On those surfaces, water sits for a while, then gets wiped or dries off. If a project involves anything holding water or fuel full time, it is outside what our products are made to do, and we would rather tell you that up front than sell you a kit that peels.

What we recommend

• Pool or baptistry interior: buy an immersion-rated pool paint or the shell manufacturer's approved refinish product from a pool supplier.
• Fuel tank: have a tank professional repair or replace it.
• The concrete around them: pool decks, baptistry room floors, tank room floors and shop floors are a good fit. Start with our epoxy floor systems, size the job with the epoxy calculator, and put together a kit in the kit builder.

If you are not sure whether a surface counts as a floor or an immersion surface, reach us at (877) 703-7699, Monday to Saturday, 8am to 6pm ET, or check the FAQ. Product data sheet available on request.

Common questions

Can I use your topcoat as a sealer inside a fountain or pond?
No. Fountains, ponds and water features hold water continuously, which is the same immersion condition as a pool. Use a product rated for immersion from a pond or pool supplier.

Will your coatings work on a pool deck that gets splashed every day?
Yes. A pool deck gets wet and then dries, which is the condition our floor coatings are designed for. Follow the prep and outdoor guidance in our pool deck guide, and add slip resistance for bare feet.

Can I coat the concrete pad under a fuel tank?
Yes, once the leak is fixed and the concrete is cleaned of fuel. For areas with regular fuel or chemical spills, a chemical-resistant system like novolac is the better choice. The coating protects the floor from spills; it does not act as the tank's containment.