Schiller Pools Blog

Opening a Fiberglass Pool for Spring the Right Way

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Key Takeaways

Remove standing water and pull off the winter cover carefully, then clean, dry, and store it in a dry location.
Refill the pool to mid-skimmer level, pull winterizing plugs from jets and skimmers, and remove Gizzmos and air pillows.
Open all valves, prime the pump, restart equipment, and bleed trapped air from the filter until water spurts out.
Run the pump continuously for 24 hours, then skim, vacuum, and brush with a soft-bristle brush before balancing chemistry.
Use liquid chlorine or non-chlorine shock instead of calcium hypochlorite to protect the gel coat and keep calcium hardness below 120 ppm.

Prep the Site and Remove Your Winter Cover

Prep the site and remove your winter cover by first clearing any standing water that’s pooled on top of it using a cover pump, or bail it out manually if you don’t have one. This is one of the first pool opening steps that protects your water from contamination. Next, pull the winter cover toward one side, preventing debris from falling into the pool. Once it’s off, clean, dry, fold, and store it in a dry location.

With the cover gone, prep the surrounding area. Trim overgrown trees and hedges to reduce future debris, then sweep away nearby leaves. Inspect the deck for damage, wear, or tear. Handling these tasks carefully sets the foundation for opening a fiberglass pool correctly, making the rest of your fiberglass pool opening smoother and more efficient.

Refill Your Fiberglass Pool and Pull the Plugs

Refill your fiberglass pool to the midpoint of the skimmer opening or halfway up the tile, then pull the plugs to reopen water flow. Pump out any groundwater that’s collected in the well pit or sump pit around the pool. This step protects your equipment. Adequate water levels prevent the pump from running dry during spring pool opening.

Next, pull out the winterizing plugs from the return jets and skimmers to reopen water flow. Remove the plastic skimmer protectors (Gizzmos) and any air pillows or pool noodles stored under the cover. Replace the winter plugs with eyeball fittings, directing flow for proper circulation. Finally, gather all winterizing equipment and store it in a dry location for next season.

Restart the Pump, Filter, and Heater

Restart the pump, filter, and heater by opening the valves on your pump, filter, and heater to restore full system flow. Then reinstall any drain plugs you removed during winterizing, and prime the pump basket with water so it doesn’t run dry.

Turn on the pump and monitor for steady water flow.
Bleed trapped air from the filter using the air relief valve until water spurts out.
Run the pump continuously for 24 hours before testing your water chemistry.

Set your timer or automation schedule for the season. Finally, verify your lighting and water features are functioning correctly before moving on to cleaning surfaces.

How Long Should You Run the Pump After Opening?

Run the pump continually for a full 24 hours after opening before you test or balance your water chemistry. This uninterrupted circulation cycle distributes water evenly through the pump, filter, and heater, clearing stagnant zones left from winterization. It also lets suspended debris and sediment reach the filter, where they’re captured effectively.

Don’t shortcut this interval. Testing water before it’s fully circulated gives inaccurate readings, since chemicals and contaminants haven’t dispersed uniformly. A complete turnover ensures your samples reflect the pool’s true condition.

During this period, confirm the pump maintains steady flow and the filter holds proper pressure. Watch for air pockets or leaks at fittings. Once the 24 hours pass, you’re ready to proceed with accurate chemistry testing.

Skim, Vacuum, and Brush Every Surface

Skim, vacuum, and brush every surface to keep your fiberglass pool clean and ready for balanced chemistry. Skim the water surface first, clearing floating leaves, insects, and debris before they sink and stain your fiberglass. Empty both the skimmer and pump baskets once you’ve finished, ensuring uninterrupted flow. After circulation begins, address sediment settled on the pool bottom, then tackle the walls and steps systematically.

Skim first, vacuum next, brush last, working in order keeps your fiberglass pristine and ready for balanced chemistry.

Vacuum the bottom to remove sediment and fine particles that accumulated over winter.
Brush walls and floor using a soft-bristle brush designed for fiberglass gel coat, never steel, which scratches the smooth surface.
Clean ladder steps, lights, and crevices where dirt or residue tends to hide.

Working in this order prevents recontamination and keeps your surfaces pristine. Precise, thorough cleaning now sets the stage for accurate water testing and balanced chemistry afterward.

Which Brush Is Safe for Fiberglass?

When brushing your fiberglass pool, choose a soft-bristle brush that cleans the surface without scratching it. Never use a steel brush, since its stiff metal bristles will gouge and permanently damage the gel coat. Protecting that smooth gel coat keeps your pool’s surface intact and easier to maintain.

Choose Soft-Bristle Brushes

Choose a soft-bristle brush when cleaning a fiberglass pool, since the gel coat surface scratches easily under abrasive tools. Steel brushes gouge the smooth finish, creating rough spots where algae and stains take hold. Match your brush to the surface and technique to protect the gel coat throughout the season.

Select a brush with nylon or poly bristles rated safe for fiberglass gel coat.
Brush walls and the floor using overhead, downward strokes to direct debris toward the main drain.
Reach ladder steps, crevices, and corners where sediment settles and circulation stays weak.

Work systematically across the entire surface after circulation begins, then vacuum the loosened sediment. Clean gently, and you’ll keep the finish smooth and stain-free.

Never Use Steel

Never use steel bristles near a fiberglass pool, because they cut into the gel coat on contact. The smooth surface that makes fiberglass easy to maintain also makes it vulnerable to abrasion. Once you scratch that coating, you expose the shell to staining, algae attachment, and progressive wear that only worsens over time.

Reach for a soft-bristle brush suitable for fiberglass gel coat instead. It removes sediment and film without gouging the surface, so you keep the finish intact while you clean.

Brush the walls and floor in overlapping strokes and apply steady, moderate pressure. Don’t grind or scrub aggressively, even on stubborn spots. Let the bristles do the work, and you’ll protect the gel coat for years.

Protect the Gel Coat

Protect the gel coat by choosing a soft-bristle brush that keeps the finish intact all season. Since fiberglass relies on its gel coat for durability, the brush you choose determines whether that finish survives. A soft-bristle brush cleans walls and floors without scratching the smooth surface. The wrong tool leaves permanent marks that compromise both appearance and structural integrity.

Follow these guidelines when brushing your fiberglass pool:

Use a soft-bristle brush designed specifically for fiberglass gel coat surfaces to lift dirt without abrasion.
Brush walls and floor thoroughly after circulation begins, reaching corners where sediment settles.
Clean ladder steps, lights, and crevices where residue hides and standard passes miss.

Apply steady, moderate pressure and let the bristles do the work. You’ll preserve the gel coat’s finish while keeping every surface clean throughout the season.

Test and Balance Your Fiberglass Pool Water

Test and balance your fiberglass pool water after circulating it for a full 24 hours. Start by adjusting total alkalinity to 80, 120 ppm, since it stabilizes every other reading. Next, test pH and aim for a range between 7.2 and 7.4, which suits fiberglass surfaces. Maintain chlorine between 1 and 3 ppm for effective sanitation. Keep calcium hardness below 120 ppm to prevent scaling on the gel coat. When you need to shock or sanitize, use liquid chlorine or non-chlorine shock instead of calcium hypochlorite, which can stain fiberglass. Work through each parameter in order, retesting after each adjustment. Balanced water protects your pool’s surface, keeps swimmers safe, and sets the stage for the final preventative steps.

What Chemicals Should You Skip on Fiberglass?

When you’re sanitizing a fiberglass pool, skip calcium hypochlorite, since it can stain the gel coat surface. Avoid calcium-based products altogether, as they raise calcium hardness and cause scaling. Reach for liquid chlorine or non-chlorine shock instead to protect the finish.

Avoid Calcium Hypochlorite

Avoid calcium hypochlorite on fiberglass surfaces because it tends to stain the gel coat and drive up calcium hardness. Although calcium hypochlorite is an effective sanitizer for many pool types, on fiberglass you want calcium hardness below 120 ppm to prevent scaling, and calcium hypochlorite works directly against that goal.

Instead, reach for gentler alternatives that sanitize without compromising the surface:

Use liquid chlorine to shock the pool and kill bacteria without adding calcium.
Apply non-chlorine shock when you need to boost sanitation while keeping hardness stable.
Retest calcium hardness after treatment to confirm it stays within the safe range.

Skip Calcium-Based Products

Skip calcium-based products beyond just calcium hypochlorite because fiberglass gel coat scales easily. Keep calcium hardness below 120 ppm to prevent scaling on the smooth surface. Adding calcium-heavy chemicals raises hardness levels, leaving mineral deposits that dull the gel coat and roughen the finish over time.

Instead, use liquid chlorine or non-chlorine shock to sanitize without introducing extra calcium. These options handle bacteria effectively while keeping your water chemistry balanced for fiberglass.

Test and balance your water, monitoring calcium hardness alongside pH and alkalinity. If levels climb too high, dilute with fresh water to bring them down.

Choosing calcium-free products protects your pool’s surface, maintains its appearance, and reduces the maintenance you’ll face throughout the swimming season.

Shock the Pool, Add Algaecide, and Leak-Check

Shock the pool to eliminate any lingering bacteria before you activate the salt cell. Use non-chlorine shock or liquid chlorine, never calcium hypochlorite, to protect your fiberglass surface from staining. After shocking, you can add a spring algaecide to stop early algae growth, and apply stain and scale control as part of routine maintenance.

Protect your fiberglass surface by choosing non-chlorine shock or liquid chlorine, never calcium hypochlorite, before activating your salt cell.

Shock with non-chlorine or liquid chlorine, then wait before activating the salt cell.
Add optional spring algaecide and stain/scale control products.
Inspect the water inspection port for groundwater and check all fittings for leaks.

Retest after 24 hours to confirm your pH, alkalinity, and chlorine levels are stable. Verify every fitting stays leak-free before regular use.

Conclusion: Opening Your Fiberglass Pool for the Season

Opening a fiberglass pool the right way sets up a clean, trouble-free swim season. It means removing the cover, topping up water, reconnecting and checking equipment, and balancing the chemistry before anyone gets in. Fiberglass pools are relatively straightforward to open thanks to their smooth, algae-resistant surface. Taking the time to do it properly, or having a pro handle it, protects the pool and gets you swimming sooner.

Get Expert Pool Construction & Care

Fiberglass pool ownership becomes easier when you start with quality construction and expert guidance from day one. At Schiller Pools in Jupiter, FL, our experienced team provides trusted Pool Construction with premium craftsmanship and 40+ years of Florida experience. Call +1 (561) 475-5997 today and get your free estimate.

Frequently Asked Questions

How Much Does It Cost to Open a Fiberglass Pool Professionally?

Professional pool openings are usually priced as a flat service fee that varies by region, pool size, and what the service includes, such as chemicals or equipment checks. It is generally an affordable seasonal cost. Getting a quote from a local pool company gives you the clearest figure, and some offer discounts for booking both opening and closing.

When Is the Best Time of Year to Open My Pool?

Most people open their pool in spring once daytime temperatures are consistently warming, often when they reach the 65 to 70 degree range. Opening a little earlier, before the water warms enough for algae, can actually make the job easier. Your local climate and swim plans determine the ideal timing.

Can I Open My Fiberglass Pool Myself or Hire a Pro?

Many owners open their own pool, since fiberglass is forgiving and the steps are manageable: remove the cover, restore the water level, reconnect equipment, and balance the chemistry. If you are unsure about the equipment or chemistry, a professional opening ensures everything starts the season right. It comes down to your comfort level and time.

How Often Should I Open and Close My Pool Each Year?

In climates with a cold winter, a pool is typically opened once in spring and closed once in fall, so one of each per year. In warm climates, some owners keep the pool open year-round and skip closing entirely. Your local weather and how much you swim in cooler months decide the schedule.

What Should I Do if My Fiberglass Pool Has Visible Cracks?

First, know that many surface marks on fiberglass are minor gel-coat spider cracks rather than structural damage. Still, any visible crack is worth having a professional inspect, since they can tell surface flaws from deeper problems and recommend the right repair. Addressing it early, before opening, prevents small issues from growing over the season.