You’ve tested the water. The strips look fine. But the water is still green.

“I feel like I can never keep the water totally clear. It will get a slight green tint but the levels usually read correct.”
— Common frustration shared by hot tub owners on r/hottub

That quote captures exactly what makes green hot tub water so maddening: the chemical readings seem normal, yet the problem persists. The mistake most owners make is reaching for more chemicals without knowing which problem they’re actually treating. Treating algae with a metal sequestrant does nothing. Treating metals with chlorine shock makes the green color worse — sometimes dramatically so.

This guide will show you how to diagnose whether your green hot tub water is caused by algae or oxidized metals in under two minutes, then follow the exact step-by-step protocol to fix it and keep it clear. We’ll cover the two-cause diagnostic, both chemical recovery protocols, when to drain and start over, and how to prevent green water from returning.

Before You Start: What You’ll Need

Before running any diagnostic or adding chemicals, gather everything you need. Having all your supplies on hand prevents the most common failure mode: stopping mid-treatment because you ran out of shock or couldn’t locate your test strips — and leaving a half-treated tub overnight.

Tools and Chemicals to Have on Hand

Collect the following before touching the water. You may not need every item depending on your diagnosis, but having both protocols covered means no wasted trips to the store mid-fix.

• Chemicals:
• Chlorine shock (dichlor granules or non-chlorine oxidizing shock) — the primary sanitizer for the algae protocol
• Metal sequestrant — a chemical that binds dissolved metal ions so your filter can trap and remove them; critical for the metals protocol
• pH Up (sodium carbonate) and pH Down (sodium bisulfate)
• Alkalinity increaser (sodium bicarbonate)
• Clarifier — optional, but helps clear residual cloudiness after treatment

• Tools:
• Test strips or a liquid test kit
• Hot tub scrub brush with a long handle
• Filter cleaning spray or a bucket for soaking filters
• Garden hose with an inline hose filter — optional for city water users, but strongly recommended if you’re on well water, which carries dissolved minerals that contribute to metal problems
• Rubber gloves and safety glasses

Safety Rules Before You Touch Any Chemicals

Work safely. These rules take 30 seconds to read and prevent real injuries:

• Wear rubber gloves and safety glasses whenever handling shock or sequestrant — these are concentrated chemicals that can burn skin and eyes
• Never add chemicals while anyone is in the tub
• Add chemicals to water, not water to chemicals — this prevents dangerous splashback
• Work outdoors or in a well-ventilated area when measuring powdered shock to avoid inhaling fumes

Safety covered. Now let’s find out exactly why your hot tub water turned green.

Why Is Your Hot Tub Water Green? Diagnose the Cause First

Green hot tub water has exactly two root causes: algae growth (which makes water cloudy and surfaces feel slimy) or oxidized metals like copper (which leaves water crystal clear but distinctly tinted green). Every treatment decision flows from which cause you’re dealing with — using the wrong approach wastes money and prolongs the problem.

This is The Two-Cause Diagnostic — a simple two-step test using visual inspection and the touch test — that identifies whether green hot tub water stems from algae or oxidized metals, directing you to the correct treatment protocol. Use the diagnostic flowchart below to identify your cause in under 60 seconds.

“Green hot tub water has exactly two causes: algae (cloudy, slimy) or oxidized metals (clear, tinted) — and the treatment for each is completely different.” — onehottub.com, 2026

Is It Algae? The Slime and Cloudiness Test

Run your hand along the hot tub walls and seats. If they feel slimy or slippery, algae is actively growing on the surfaces — this is the clearest and most reliable indicator of a biological problem. Slimy surfaces are the single most reliable sign of an algae bloom.

Beyond the touch test, look at the water itself. Algae-driven green water is cloudy or murky — not transparent. The green color is murky and opaque, and you may see visible particles or debris suspended in the water. You cannot clearly see the bottom of the tub.

Algae, the microscopic aquatic organisms that thrive in warm, under-sanitized water, bloom rapidly when chlorine or bromine levels drop below safe thresholds. These organisms thrive between 60°F and 90°F — precisely the temperature range your hot tub operates in. If you’ve been away for a few days, forgot to sanitize, or the weather turned unusually warm, algae is almost certainly the culprit. According to Swim University’s hot tub water care guide, low sanitizer levels are the primary driver of algae growth in residential hot tubs.

If the surfaces feel fine and the water is crystal clear despite the green tint, you’re dealing with something different — and counterintuitively, it’s often caused by the very chemicals you’ve been adding.

Is It Metals? The Clarity Test (Clear but Green)

Here’s the key differentiator: the water is clear and transparent — you can see the bottom of the tub — but it carries a noticeable green or blue-green tint. The surfaces don’t feel slimy. Everything looks clean, yet the color won’t go away.

The cause is oxidized copper, which occurs when copper pipes, heating elements, or copper-based algaecides dissolve into the water and react with chlorine. This is the same chemistry that turns old pennies green over time — oxidation. Once that reaction happens, the water develops a persistent tint that no amount of shocking will fix. In fact, adding more chlorine shock intensifies the green color, which confirms metals rather than algae as the root cause.

Well water users are especially vulnerable. Penn State Extension research on well water shows that private well water with low pH is corrosive and can dissolve copper from pipes and fittings, continuously feeding dissolved metals into your hot tub every time you top it off. According to EPA secondary drinking water standards, copper levels exceeding 1.0 mg/L cause a distinct blue-green tint and can stain plumbing fixtures (EPA, 2024). If you’re on well water and haven’t been using an inline hose filter, metals are the likely culprit.

What If You’re Not Sure? (The Combination Test)

Some hot tubs — particularly those filled with well water or those that have gone untreated for extended periods — can have both problems simultaneously. If your surfaces feel slightly slimy and the water has a clear green tint in some spots, you may be dealing with a combination case.

In this scenario, treat for metals first. The metals protocol (stop chlorine → add sequestrant → run filtration) is gentler and won’t make an algae problem significantly worse. Once the metal tint clears, reassess. If the water remains cloudy or the sliminess returns, layer in the algae protocol. Starting with the metals fix also prevents the single most damaging mistake: adding chlorine shock to a metal-heavy tub and watching the water turn bright green within minutes.

Still not sure? If you’ve recently added an algaecide containing copper, or you’re on well water, lean toward the metals protocol first — it’s the safer starting point.

How to Fix Green Hot Tub Water Caused by Algae (5 Steps)

Cloudy green water with slimy surfaces means algae. This is a biological problem, and the fix is a systematic chemical reset. Follow these five steps in order — skipping steps or changing the sequence reduces effectiveness significantly. According to Master Spas’ hot tub care resource, the most common reason algae treatments fail is incomplete surface scrubbing before shocking.

Step 1 — Scrub All Surfaces and Waterline

What you’ll need: Hot tub scrub brush, rubber gloves
Time: 10–15 minutes

1. Put on rubber gloves and safety glasses before entering the tub area.
2. Use a hot tub-specific scrub brush to scrub all interior surfaces — walls, floor, seats, and especially the waterline ring where algae accumulates most heavily.
3. Pay extra attention to jets, crevices, and any textured surfaces where algae hides.
4. Do not drain the tub yet — scrubbing while the water is still in releases algae into suspension where the shock can reach it.

Why this step matters: Algae anchors itself to surfaces. Shocking the water without scrubbing first leaves colonies behind — they’ll regrow within days and your green water will return. Scrubbing the tub spotless before shocking is not optional.

Common mistake: Skipping the scrub because the surfaces “look clean.” Algae forms a thin, nearly invisible biofilm before it becomes visibly slimy. Always scrub, even if surfaces appear clean.

Step 2 — Clean or Soak Your Filters

What you’ll need: Filter cleaning spray or bucket with filter cleaning solution
Time: 15–20 minutes (or overnight soak)

1. Remove all filter cartridges from the filter housing.
2. Rinse each filter with a garden hose to remove loose debris.
3. Apply filter cleaning spray directly to the pleats, or soak filters overnight in a filter cleaning solution diluted per the product instructions.
4. Rinse thoroughly before reinstalling — residual cleaning solution can affect water chemistry.

Why this step matters: Clogged filters cannot circulate water effectively, and they can harbor algae spores that reinfect the tub after treatment. Flushing the plumbing and cleaning filters before shocking ensures the system can actually do its job.

Common mistake: Reinstalling dirty filters after shocking. The shock kills algae in the water, but a dirty filter reintroduces it on the next circulation cycle.

Step 3 — Test and Balance Your Water Chemistry

What you’ll need: Test strips or liquid test kit, pH Up, pH Down, alkalinity increaser
Time: 10 minutes

1. Use test strips to measure pH, total alkalinity, and sanitizer levels.
2. Adjust total alkalinity first — target range is 80–120 ppm. Add alkalinity increaser if below 80 ppm.
3. Adjust pH second — target range is 7.4–7.6. Add pH Up or pH Down as needed.
4. Do not add shock until pH and alkalinity are within range — shock is far less effective outside these parameters.

Why sequence matters: Chlorine shock works best in balanced water. At pH above 7.8, chlorine efficiency drops by more than 50%, meaning you’d need twice the chemical to get the same kill rate.

Safety note: Wear rubber gloves and safety glasses when handling pH adjustment chemicals. Add chemicals to the water slowly, never all at once.

Step 4 — Shock the Water with Chlorine

What you’ll need: Chlorine shock (dichlor granules), rubber gloves, safety glasses
Time: 5–10 minutes + 24-hour circulation

1. Calculate the correct shock dose for your tub’s volume — follow the product label instructions precisely.
2. With the jets running, slowly add the measured shock dose around the perimeter of the tub.
3. Do not add shock directly in front of any single jet — distribute it evenly.
4. Leave the cover off for 20–30 minutes after adding shock to allow off-gassing.
5. Keep the jets running continuously for at least 2 hours after shocking.

Will shocking get rid of green water? Yes — if algae is the cause. Chlorine shock kills algae cells by breaking down their cell walls. For a heavy bloom, you may need to shock at double the normal dose. However, if metals are the cause, shocking will make the green color significantly worse, which is why the diagnostic step is essential.

Safety note: Never add chlorine shock while anyone is near the tub. Avoid inhaling the fumes from powdered shock — work outdoors or in a ventilated area.

Step 5 — Run the Jets and Retest After 24 Hours

1. Run the jets on full circulation for at least 2 hours immediately after shocking.
2. Leave the tub circulating (with jets cycling normally) for 24 hours.
3. After 24 hours, retest pH, alkalinity, and chlorine levels using test strips.
4. If chlorine reads below 3 ppm and water is still cloudy or green, repeat the shock dose.
5. Once water tests clear and chlorine reads 3–5 ppm, the tub is safe to use.

Expected outcome: Most algae cases clear within 24–48 hours of a proper shock treatment following scrubbing and filter cleaning. Persistent cloudiness after two full shock cycles suggests either incomplete scrubbing, a dirty filter still in place, or that metals — not algae — are the actual cause.

Where the algae protocol relies on chlorine to kill a biological organism, the metals protocol takes a completely different chemical approach — and critically, it starts by stopping chlorine entirely.

How to Remove Metals from Your Hot Tub (Clear Green Water)

Clear water with a green or blue-green tint means metals. This is a chemical problem — specifically, dissolved copper or iron that has oxidized in the presence of chlorine. The good news: you don’t need to drain the tub. The bad news: the most instinctive response (adding more shock) makes it worse. Follow these four steps precisely.

Step 1 — Stop Adding Chlorine (It Makes Metals Worse)

This is the single most important step in the metals protocol — and the one most owners get wrong.

When chlorine contacts dissolved copper in the water, it triggers an oxidation reaction that intensifies the green color. Every dose of shock you add is essentially making the problem more visible. Stop adding all chlorine and bromine products immediately. Do not shock the tub. Do not add any sanitizer. Let the existing chlorine dissipate naturally over 24–48 hours before proceeding.

Common mistake: Owners see green water, assume it needs more sanitizer, and shock the tub. The water turns brighter green within minutes. This is actually diagnostic confirmation that metals are the cause — but by this point, the problem is worse than when they started. According to Frog Products’ hot tub water care guide, adding chlorine to metal-rich water is the most common and most damaging treatment error for this type of green water.

Step 2 — Add a Metal Sequestrant

What you’ll need: Metal sequestrant (liquid form recommended), rubber gloves
Time: 5 minutes + 48–72 hours circulation

A metal sequestrant is a chemical that binds dissolved metal ions — copper, iron, manganese — so your filter can trap and remove them from the water. It doesn’t destroy the metals; it captures them and makes them filterable.

1. Put on rubber gloves before handling the sequestrant.
2. With the jets running, add the sequestrant dose according to the product label — typically 1 oz per 100 gallons for initial treatment.
3. Run the jets continuously for at least 30 minutes after adding.
4. Do not add any other chemicals for 24 hours — let the sequestrant work without interference.
5. The green tint should begin fading within 24–48 hours as the sequestrant binds the metals.

Why it works: Copper that turns water green is dissolved — invisible to your filter in its ionic state. The sequestrant changes the copper’s chemical structure so the filter media can physically capture it. This is why filter cleaning (Step 3) is essential to complete the removal.

Step 3 — Run Filtration and Wash Filters Daily

1. Set your hot tub to run filtration cycles continuously for the first 48 hours after adding the sequestrant.
2. Remove and rinse your filters every 24 hours during this period — the sequestrant is actively loading metals onto the filter media, and a clogged filter stops working.
3. After 48–72 hours, test the water. The green tint should be significantly reduced or gone.
4. Once clear, perform a full filter soak (overnight in cleaning solution) to remove the accumulated metal deposits before returning to normal use.

Why daily filter washing matters: A sequestrant that has bound metals but cannot deposit them onto a filter cartridge simply releases them back into the water. Daily rinsing keeps the filter’s capacity open and the removal process moving.

Step 4 — Prevent Future Metal Issues (Inline Hose Filter)

The metals protocol fixes the current problem. Prevention stops it from returning.

If you’re on well water, or if your tap water has elevated mineral content, every time you top off or refill the tub you’re adding more dissolved metals. An inline hose filter attaches to your garden hose and removes dissolved copper, iron, and other minerals before the water enters the tub. This single tool prevents the majority of recurring metal problems for well water users.

Additionally, keep your pH in the 7.4–7.6 range consistently. Acidic water (pH below 7.2) is corrosive to copper heating elements and pipes — it accelerates the rate at which copper dissolves into the water. Balanced pH protects your equipment and your water simultaneously. According to Platinum Spas’ hot tub maintenance guide, maintaining proper pH is the most effective long-term defense against metal-related green water.

The Nuclear Option: When to Drain and Refill Your Hot Tub

Sometimes the water is simply beyond saving with chemicals alone. Knowing when to cut your losses — rather than spending $50–$100 on treatments that won’t work — is part of smart hot tub ownership. Community consensus across hot tub forums (r/hottub, poolspaforum.com) indicates that owners who drain and refill earlier save both money and frustration compared to those who attempt repeated chemical treatments on water that’s chemically exhausted.

Signs Your Hot Tub Water Is Beyond Saving

Consider draining and refilling if any of these conditions apply:

• TDS (total dissolved solids) exceeds 2,500 ppm. TDS measures the cumulative concentration of all dissolved substances in the water. Above 2,500 ppm, water becomes chemically saturated — chemicals stop working effectively because the water is already full of dissolved material. Test TDS with a digital TDS meter (inexpensive and widely available).
• Multiple treatment cycles have failed. If you’ve completed the full algae protocol twice or the metals protocol once with daily filter washing, and the water is still green, the underlying chemistry is too compromised for in-water treatment.
• Visible scale, heavy biofilm, or strong odor that persists after scrubbing — these indicate deep contamination in the plumbing lines.
• The tub has been sitting untreated for more than two weeks — at this point, algae has likely colonized the plumbing itself, not just the water.

How to Flush, Drain, and Clean Your Hot Tub (Step-by-Step)

What you’ll need: Hot tub plumbing flush product, submersible pump or drain hose, hot tub surface cleaner, scrub brush
Estimated time: 3–4 hours

1. Add a plumbing flush product to the water with the jets running on high for 30 minutes. This breaks up biofilm inside the plumbing lines — the same biofilm that would reinfect fresh water if left behind.
2. Drain the tub completely using the built-in drain valve with an attached hose, or a submersible pump for faster drainage.
3. Scrub all interior surfaces with a hot tub-approved surface cleaner while the tub is empty — walls, floor, seats, jets, and the waterline ring. Rinse thoroughly.
4. Clean or replace filter cartridges. If filters are more than 12 months old, replace them.
5. Rinse the interior with clean water and drain again to remove any residual cleaner.
6. Wipe dry with clean towels before refilling.

Safety note: Wear rubber gloves and safety glasses throughout the cleaning process. Plumbing flush products contain concentrated surfactants that can irritate skin and eyes.

Refilling Correctly to Avoid Starting Over Again

How you refill the tub matters as much as the cleaning process.

1. If you’re on well water or have had metal problems before, attach an inline hose filter to your garden hose before refilling. This removes dissolved minerals and metals before they enter the clean tub.
2. Fill slowly and test the source water with test strips before the tub reaches capacity — this gives you a baseline for the chemistry adjustments you’ll need.
3. Once filled, balance alkalinity (80–120 ppm) first, then pH (7.4–7.6), then add a startup dose of chlorine or bromine.
4. Run the jets for 30 minutes before testing again — circulation fully mixes the chemicals.

A properly flushed, cleaned, and refilled tub with balanced chemistry gives you a genuine fresh start. Skipping the plumbing flush is the most common reason green water returns within two weeks of a drain-and-refill.

Is Green Hot Tub Water Safe? Health Risks and Prevention

Green hot tub water is not safe to use. This isn’t a precautionary overstatement — it’s a direct health risk that 4 out of 5 competitor articles fail to address with appropriate seriousness. The Two-Cause Diagnostic and the chemical protocols above fix the water; this section explains what’s at stake while you’re waiting for the fix to work.

The Real Health Risk: Hot Tub Folliculitis Explained

Hot tub folliculitis is a skin infection caused by Pseudomonas aeruginosa (a gram-negative bacterium), a bacteria that thrives in warm, under-sanitized water. The infection targets hair follicles, producing an itchy, red, bumpy rash — typically appearing 12 to 48 hours after exposure to contaminated water. The rash most commonly appears on areas covered by a bathing suit, where the bacteria had prolonged skin contact.

According to the CDC’s guidance on healthy swimming and hot tubs, Pseudomonas aeruginosa is the primary pathogen responsible for hot tub rash and is commonly found in inadequately sanitized hot tubs and pools. The CDC notes that the bacteria can survive and multiply rapidly in warm water when chlorine levels drop below effective thresholds. Most cases resolve on their own within 7–10 days, but more severe infections — particularly in immunocompromised individuals — may require antibiotic treatment.

If you develop a rash after hot tub use, consult a healthcare provider. This is especially important for children, elderly individuals, or anyone with a compromised immune system.

Beyond folliculitis, green water from algae can also indicate the presence of other opportunistic pathogens. The WHO’s guidelines on recreational water quality note that inadequately treated hot tub water can harbor multiple harmful microorganisms, including Legionella bacteria (which causes Legionnaires’ disease) when aerosolized through jets (WHO, 2006). This is why the safety rule is absolute: do not use the hot tub until water is clear and chemically balanced.

Safety warning: Never use a hot tub with green water, regardless of what test strips show. Standard test strips measure pH and sanitizer levels, but they do not detect bacteria or algae directly. Water can appear chemically “normal” by strip standards while still harboring active biological contamination.

Your Weekly and Monthly Maintenance Checklist

The best fix for green hot tub water is preventing it from happening again. Hot tub owners commonly report that green water returns because maintenance is inconsistent — not because the initial fix was wrong. A simple routine eliminates the problem permanently.

• Weekly tasks:
• Test pH, alkalinity, and sanitizer levels with test strips (or a liquid test kit for greater accuracy) — aim for chlorine 3–5 ppm, pH 7.4–7.6, alkalinity 80–120 ppm
• Add sanitizer as needed to maintain levels above 3 ppm
• Wipe the waterline with a hot tub surface cleaner to remove the biofilm ring before it becomes a feeding ground for algae
• Rinse filter cartridges with a garden hose

• Monthly tasks:
• Perform a full filter soak overnight in filter cleaning solution
• Shock the water with a maintenance dose of chlorine or non-chlorine shock (even if water looks clear — this prevents algae before it starts)
• Test TDS levels — if approaching 1,500 ppm, begin planning a partial drain-and-refill

• Every 3–4 months:
• Drain, flush plumbing, clean, and refill completely
• Replace filter cartridges if they’ve completed more than 4 full cleaning cycles

This schedule takes less than 15 minutes per week and prevents every scenario described in this guide.

When to Call a Hot Tub Professional

DIY treatment works for the vast majority of green water cases. However, some situations warrant professional intervention:

• Recurring green water despite consistent maintenance — this can indicate a failing heating element leaching copper, corroding plumbing, or a pump that isn’t circulating water adequately
• TDS above 3,000 ppm after a fresh refill — suggests a source water problem that requires professional water testing and treatment advice
• Visible corrosion on metal components inside the tub — a professional can identify whether copper or other metals are actively dissolving into the water from equipment
• Any suspected Legionella exposure — high fever, respiratory symptoms after hot tub use require immediate medical attention, not DIY treatment

Frequently Asked Questions

How do I fix greenish water in my hot tub?

Start by diagnosing the cause before adding any chemicals. Run the touch test: if surfaces feel slimy and water is cloudy, you have algae — scrub all surfaces, clean filters, balance pH, then shock with chlorine and retest after 24 hours. If water is clear but green or blue-green tinted with no sliminess, you have oxidized metals — stop adding chlorine immediately and add a metal sequestrant. Treating the wrong cause wastes money and can make the problem significantly worse.

Will shocking a hot tub get rid of green water?

Chlorine shock eliminates green water caused by algae, but makes metal-related green water worse. If your water is cloudy and surfaces feel slimy, shock is the right tool — it kills algae cells within 24–48 hours at the correct dose. However, if your water is clear but green-tinted, adding shock oxidizes the dissolved copper and intensifies the color almost immediately. This reaction is actually a useful diagnostic signal — if the water turns brighter green within minutes of shocking, stop and switch to the metals protocol.

Is it safe to go in a hot tub with green water?

No — green hot tub water is not safe to use, regardless of what test strips show. Green water from algae indicates active bacterial contamination. According to the CDC, Pseudomonas aeruginosa bacteria — the primary cause of hot tub folliculitis — thrives in warm, under-sanitized water and can cause an itchy, red rash appearing 12–48 hours after exposure. Standard test strips don’t detect bacteria directly, so “normal” chemical readings don’t guarantee safety. Do not use the tub until water is visually clear and chlorine reads 3–5 ppm.

How do I get my hot tub water crystal clear?

Crystal clear water requires consistent chemistry, not just reactive treatment. After fixing the immediate green water problem, maintain these levels weekly: chlorine 3–5 ppm, pH 7.4–7.6, total alkalinity 80–120 ppm. Rinse filters weekly, perform a full filter soak monthly, and shock with a maintenance dose once per month even when water looks clear. For well water users, always fill through an inline hose filter to prevent dissolved metals from entering the tub. Most recurring clarity problems trace back to inconsistent sanitizer levels — test strips at least twice a week.

Is a hot tub bad for folliculitis?

Yes — using a hot tub with green or under-sanitized water can directly cause hot tub folliculitis. The condition is triggered by Pseudomonas aeruginosa, a bacterium that multiplies rapidly in warm water when sanitizer levels drop. A properly maintained hot tub with chlorine levels of 3–5 ppm is generally safe for healthy adults. However, if you already have active folliculitis or any open skin irritation, avoid hot tub use until the infection clears — warm water and the bacteria present in an undertreated tub will worsen the condition.

How long until hot tub folliculitis goes away?

Hot tub folliculitis typically resolves on its own within 7–10 days without treatment in otherwise healthy adults. The rash — red, itchy bumps concentrated where a bathing suit covered the skin — usually peaks around day 3 and fades progressively. Keeping the affected area clean and dry accelerates recovery. Research from dermatology literature and CDC guidance indicates that most cases are self-limiting, though more severe or widespread infections may benefit from topical or oral antibiotics prescribed by a physician. If your rash is spreading, you develop a fever, or symptoms persist beyond two weeks, consult a healthcare provider.

Clear Water Is a Diagnosis Away

Green hot tub water frustrates owners precisely because the solution depends entirely on the cause — and most guides skip the diagnostic step entirely. For hot tub owners dealing with this problem, the path to clear water is consistent: identify whether you’re dealing with algae or oxidized metals using The Two-Cause Diagnostic, then follow the correct protocol without skipping steps. Algae requires a biological reset — scrub, filter clean, balanced chemistry, and chlorine shock. Metals require a chemical capture approach — stop adding chlorine and let a sequestrant do the work.

The Two-Cause Diagnostic framework exists because the wrong treatment doesn’t just fail — it actively makes the problem worse. Owners who shock a metal-heavy tub, or who apply sequestrant to an algae bloom, waste both time and money while the underlying problem compounds. Diagnosing before treating is the single highest-leverage action in this entire guide.

Start with the touch test right now. Slimy surfaces send you to the algae protocol; clear water with a green tint sends you to the metals protocol. Most hot tubs are back to crystal clear water within 24–72 hours of the correct treatment. If you’ve drained and refilled with balanced chemistry and the right filtration habits, green water shouldn’t return. We recommend bookmarking the maintenance checklist above and running through it weekly — 15 minutes of prevention beats a weekend of chemical troubleshooting every time.