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BioGuard Banish | Non-Staining Pool Algaecide

SKU: 23500BIO
$39.99

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Description

BioGuard Banish is a patented, non-staining copper algaecide that kills all types of swimming pool algae — green, mustard, and black — with visible results in 24 hours. What sets it apart from every other copper algaecide is a single practical advantage: it can be added during a shock treatment.

That matters more than it sounds. Most copper-based algaecides have to be separated from shock by hours or a full day, because high free chlorine and copper chemistry interfere with each other. That turns algae remediation into a multi-day sequence with waiting periods, and it's where people lose track and skip steps. Banish is approved for use during shock, so the whole treatment collapses into one session — fewer steps than other copper-based algaecides, and less opportunity to get the order wrong.

The formula is 3.3% metallic copper, patented and specifically engineered to be non-staining. Staining is the reputational problem with copper algaecides, and it's the reason many pool owners avoid them despite copper being the most effective tool against mustard and black algae. Banish is built to deliver that effectiveness without the deposit risk that comes with ordinary copper sulfate products.

It's also non-foaming and does not affect pH, so it works in pools with attached spas, spillovers, waterfalls, and jetted returns without producing a lingering head of foam, and it doesn't trigger a rebalancing cycle after treatment. Swimmers can return soon after application, and the formula clears the water while it kills the algae.

Approved for use in chlorine and bromine pools and all pool types. Dosing runs from a light weekly preventative to a heavy remediation rate for visible growth.

Pro Tip: The shock compatibility is the reason to choose this one, so use it. On most copper algaecides you shock the pool, wait for chlorine to come back down, then add the algaecide — a sequence spread across a day or more where the algae gets a head start in between. With Banish you can brush, shock, and treat in a single session. That matters most with black algae, where the whole strategy depends on breaking the protective layer open with a brush and hitting the exposed colony immediately. Every hour between brushing and treating is time the colony spends rebuilding its defenses.

Brand

BioGuard®

What's in the Box
  • 1 x BioGuard Banish, 1 quart (32 fl oz) bottle
  • Full manufacturer label with dosing rates and safety information

At the weekly preventative rate, one quart treats a 20,000-gallon pool for roughly ten weeks. At the algae removal rate, a quart is a full treatment for a 20,000-gallon pool.

Key Features

Approved for Use During Shock Treatments

The defining advantage. Most copper algaecides require separation from shock; Banish doesn't, which collapses a multi-step remediation into a single session.

Patented Non-Staining Formula

Engineered to deliver copper's effectiveness against stubborn algae without the surface staining that gives ordinary copper algaecides their reputation.

Kills and Prevents Green, Mustard, and Black Algae

Effective across all three common pool algae types, including the two that routinely survive an adequate chlorine residual.

Results in 24 Hours

Fast-acting formula with visible results within a day of application, rather than a multi-day wait to know whether the treatment worked.

Non-Foaming

Won't produce the persistent foam quat-based algaecides are known for, so it suits pools with attached spas, spillovers, waterfalls, or jetted returns.

Does Not Affect pH

No rebalancing needed after application, which is one less correction in an already busy remediation routine.

Clears Water While It Kills Algae

The formula addresses clarity alongside algae control rather than leaving cloudy water behind for a separate product to handle.

Quick Return to the Water

Swimmers can return soon after treatment, subject to free chlorine being back in the normal range after any accompanying shock.

For Chlorine and Bromine Pools, All Pool Types

Approved across both sanitizer programs and every common pool surface.

How It Works

The active ingredient is copper at 3.3% metallic. Copper works against algae through a mechanism completely unrelated to how chlorine works, and that independence is what makes it valuable.

Chlorine kills by oxidation — it destroys cell structures by stripping electrons. Copper instead binds to enzymes inside the algae cell that drive photosynthesis and respiration, shutting those processes down from the inside. The algae doesn't get oxidized; it gets poisoned metabolically.

That distinction explains why copper reaches algae that chlorine can't. Mustard algae is chlorine-resistant and hides in shaded areas, filters, and on equipment. Black algae anchors roots into plaster and grout and grows a waxy protective layer that keeps oxidizers out. A pool can hold a textbook chlorine residual all season and still lose to either one. Copper works through a different door.

The patented non-staining formulation addresses copper's long-standing weakness. Copper stains when it comes out of solution and deposits onto pool surfaces — typically triggered by low pH, existing metals in the water, or overdosing. Banish is formulated to keep copper in solution and available to work rather than free to deposit, which is what earns the non-staining claim.

The shock compatibility is the other engineering achievement here. High free chlorine levels interfere with many copper algaecides, which is why competing products specify waiting until chlorine returns to normal before dosing. Banish is approved for application during shock treatment, meaning the oxidizer and the algaecide can work on the same colony at the same time — chlorine attacking from the outside while copper disrupts the cell's metabolism.

Worth understanding about scope: Banish is an algaecide, not a sanitizer. It doesn't disinfect and doesn't replace chlorine or bromine. And while it's effective against established growth at the removal rate, the far cheaper path is the weekly preventative dose — algae that never establishes doesn't need to be killed.

Pro Tip: Non-staining does not mean stain-proof — test for metals before you treat. This is a copper product at 3.3% metallic, and the patented formulation dramatically reduces deposit risk without eliminating the underlying chemistry. Two conditions still raise it: low pH, which makes copper far more likely to come out of solution, and pre-existing metals in the water, common on well water or in pools that have used copper products before. Keep pH at 7.4–7.6, test for metals if you're on a well or have a staining history, and add a stain and scale inhibitor if any are present. And stay at the label dose — overdosing a copper algaecide is still the most reliable way to create a stain you then pay to remove.

Directions for Use

Dosage Reference

  • Weekly prevention: 1.5 fl oz per 10,000 gallons
  • Every-other-week prevention: 3 fl oz per 10,000 gallons
  • Algae removal: 16 fl oz per 10,000 gallons

Before You Start

  1. Confirm all pool equipment is working properly and clean or backwash the filter if needed.
  2. Establish and maintain proper chlorine or bromine levels.
  3. Balance the water — pH 7.4–7.6 in particular, since low pH increases copper staining risk.
  4. Test for metals if you have well water or a staining history, and add a stain and scale inhibitor if any are present.
  5. Confirm your pool's actual gallon capacity before measuring.

Routine Prevention

  1. Apply 1.5 fl oz per 10,000 gallons weekly, or 3 fl oz per 10,000 gallons every other week.
  2. Add with the pump and filter running, distributing around the pool.
  3. Stay on schedule through the entire swim season. A skipped stretch in peak heat is where most algae problems begin.

Algae Removal

  1. Brush all visible algae thoroughly, using a brush compatible with your pool finish. Pay particular attention to steps, ladders, corners, and the areas around skimmers and lights.
  2. Vacuum out loose debris.
  3. With the pump running, apply 16 fl oz per 10,000 gallons, concentrating over the areas of heaviest growth.
  4. This product may be applied during a shock treatment, so the shock and the algaecide can go in the same session — added to the pool separately, not mixed together.
  5. Circulate continuously and allow 24 hours for results.
  6. Brush all surfaces again the following day and vacuum out dead algae.
  7. Do not swim until free chlorine has returned to the normal 1–4 ppm range.
  8. Repeat if algae persists.
  9. Resume weekly preventative dosing once the pool is clear.

Preventing a Recurrence

  • Return to the weekly preventative dose immediately after clearing a bloom
  • With mustard algae, disinfect brushes, floats, toys, and ladders — it survives on equipment and reinfects
  • With black algae, keep brushing the affected areas for several weeks; surviving roots regrow under a fresh protective layer
  • Maintain a consistent sanitizer residual, since dips are when algae establishes
  • Increase circulation hours, especially in shaded corners and dead spots

Storage and Handling

  • Store in a cool, dry, well-ventilated area, out of direct sunlight and protected from freezing
  • Keep the container tightly closed and clearly labeled
  • Store separately from sanitizers, acids, and oxidizers
  • Keep out of reach of children and pets
  • Read and follow all label precautions, first aid, and disposal directions before use

Pro Tip: Prevention costs roughly a tenth of remediation, and the label numbers make the argument. Weekly prevention runs 1.5 fl oz per 10,000 gallons. Clearing visible algae takes 16 fl oz per 10,000 gallons — more than ten times the product, plus the shock, plus the brushing, plus 24 hours of waiting, plus vacuuming out dead algae afterward, plus a pool nobody can use while it happens. An entire season of weekly dosing costs less than one recovery. Set a recurring reminder alongside your weekly shock and treat them as a single routine.

Specifications
  • Brand: BioGuard
  • Product Type: Patented non-staining copper algaecide
  • Form: Liquid
  • Volume: 1 quart (32 fl oz)
  • Manufacturer Part Number: 23500BIO
  • Active Ingredient: Copper (metallic), 3.3%
  • Other Ingredients: 96.7%
  • Algae Types Controlled: Green, mustard, and black — all types
  • Speed of Action: Results in 24 hours
  • Shock Compatibility: Approved for use during shock treatments
  • Staining: Patented non-staining formula
  • Foaming: Non-foaming
  • Effect on pH: None — no readjustment necessary
  • Weekly Preventative Dose: 1.5 fl oz per 10,000 gallons
  • Biweekly Preventative Dose: 3 fl oz per 10,000 gallons
  • Algae Removal Dose: 16 fl oz per 10,000 gallons
  • Recommended pH Range: 7.4–7.6
  • Swim Return: Soon after treatment; after shock, when free chlorine reads 1–4 ppm
  • Sanitizer Compatibility: Chlorine and bromine pools
  • Suitable Surfaces: Plaster, gunite, vinyl liner, fiberglass, painted
  • Suitable For: Pools with attached spas, spillovers, water features, and jetted returns
  • Not A Substitute For: Sanitizer, shock, or brushing
  • Shipping Classification: DOT-regulated — ground shipping only
Compatibility

Pool Types and Surfaces

  • In-ground and above-ground pools
  • Plaster and gunite
  • Vinyl liner
  • Fiberglass
  • Painted surfaces
  • Sand, cartridge, and DE filtration

Sanitizer Programs

  • Chlorine pools — approved
  • Bromine pools — approved
  • Salt chlorine generator pools — compatible; a salt pool is a chlorine pool
  • Mineral system pools — verify total copper with a full water test first, since mineral systems and this product both contribute copper
  • Biguanide pools — verify before use. Biguanide programs run their own dedicated algaecide, and the shock-treatment advantage doesn't apply since a biguanide pool can't accept chlorine shock.

Choosing Between BioGuard's Algaecides

  • Banish — copper-based, patented non-staining, non-foaming, and the only one approved for use during shock. Best when you're remediating an active algae problem and want to do it in one session, or when foaming matters.
  • A dual-action algaecide combining polyquat and copper attacks through two mechanisms at once, which helps penetrate mature colonies. Best for stubborn established growth where you have time for a staged treatment.
  • A quat-only preventative contains no metals at all, costs less per season, and is the economical choice for pure weekly prevention — but it foams, and it's weaker against mustard and black algae.
  • All three are preventatives as well as treatments; the differences are chemistry, foaming behavior, and how they interact with shock.

What It Does Not Do

  • Not a sanitizer. Provides no disinfection and maintains no sanitizer residual.
  • Not a shock or oxidizer. It works alongside a shock treatment, not instead of one.
  • Not a substitute for brushing. Mature algae must be physically disturbed for treatment to reach it.
  • Not for spas or hot tubs. This is a pool product dosed per 10,000 gallons.

Important Handling Cautions

  • Never mix with other chemicals in a bucket or container. Being approved for use during a shock treatment means adding both to the pool separately, not combining them before application.
  • Test for metals before use if you have well water or a history of staining.
  • Do not exceed label dosing.

Most products purchased from our online shop within the last 30 days are eligible for return. Please review our return policy to see the list of items that cannot be returned.

Some major items that are non-returnable:

  • Gift cards
  • Electronics
  • Pumps / Motors
  • Hot Tubs
  • Closeouts
  • Fireplaces
  • Electric Fireplaces
  • Massage Chairs
  • See return policy below for full list of non-returnables.

BioGuard® Brand FAQs

What is the BioGuard 3-Step Care System?

It's the brand's core program for traditional chlorine pools, and it reduces routine care to three jobs.Step 1, sanitize— SilkGuard Complete® tabs or sticks maintain a continuous chlorine residual that kills bacteria and controls algae between applications.Step 2, shock— Smart Shock® is applied weekly to oxidize the organic waste bathers leave behind, break apart chloramines, and restore clarity.Step 3, prevent— Algae Complete® stops algae before it establishes rather than fighting it after it blooms. The system works in pools of any size and surface type that circulate 10 to 24 hours per day.

What's the difference between BioGuard and SpaGuard?

They're sister brands from the same water-care company.BioGuard is the swimming pool line. SpaGuard is the spa and hot tub line.The split isn't marketing — pool dosing is calculated for tens of thousands of gallons at ambient temperature, while spa dosing is calculated for a few hundred gallons at 100°F. Pool packaging makes accurate spa measurement nearly impossible, and a pool-sized dose in a hot tub is a serious overdose. Match the product line to the vessel.

Which BioGuard program is right for my pool?

Equipment usually decides it. Pools running a standard chlorinator, feeder, or skimmer application belong on the3-Step Care System. Pools with a salt chlorine generator should be on thesalt pool programs— Mineral Springs® or SaltScapes® — which are formulated around the specific scale, balance, and cell-care demands of a generator. Owners who want no chlorine or bromine in the water at all use BioGuard'snon-chlorine biguanide program, which is a fully separate chemistry with its own sanitizer, oxidizer, and algaecide.

Can I mix BioGuard products with chemicals from other brands?

Basic balancers are chemically generic and generally interchangeable — alkalinity increaser is sodium bicarbonate no matter whose label is on the bucket. The real risk sits withsanitizer programs and specialty additives. Never introduce chlorine or bromine into a biguanide pool; the two chemistries destroy each other and produce cloudy water, gummy filter fouling, and a collapsed sanitizer residual. Also avoid stacking algaecides and clarifiers from different brands, since overlapping actives can cause foaming or staining. And regardless of brand, never combine two products in the same bucket, scoop, or feeder — always add them separately with circulation running between.

What is SilkGuard Technology?

SilkGuard® is a conditioning technology built into BioGuard's chlorinating tabs and sticks. It softens the feel of the water against skin and helps protect pool surfaces and equipment from scale formation, so the sanitizer is doing two jobs at once. SilkGuard Complete® products also carrySunShield® Technology, which shields free chlorine from ultraviolet breakdown. UV loss is the largest single drain on chlorine in an outdoor pool during summer, so protecting the residual directly reduces how much sanitizer you consume over a season.

Do BioGuard products work with salt chlorine generators?

Yes. A salt pool is still a chlorine pool — the generator simply produces the chlorine on site instead of you adding it from a bucket. Salt pools still need balancing, weekly oxidation, algae prevention, and scale protection, and they have one extra demand a standard pool doesn't: the generator cell itself accumulates scale and needs periodic cleaning. BioGuard's salt-specific programs are built around exactly those requirements.Do not skip testing on a salt pool— the automation controls chlorine production, not water balance.

About BioGuard®

BioGuard is a professional swimming pool care line built on a simple premise: pool chemicals work better as a program than as a shelf of unrelated purchases. Most water problems homeowners fight through the summer aren't caused by a bad product. They're caused by good products working against each other, applied out of sequence, in water whose balance was never corrected in the first place. BioGuard's entire approach is organized around fixing that — matched products, a defined order of operations, and a diagnostic process behind the recommendation.

The brand sits under the KIK Consumer Products umbrella alongside its spa counterpart, SpaGuard, and it covers the full range of pool water care: sanitizers, shocks, algaecides, balancers, water enhancers, surface cleaners and problem solvers, salt pool products, and off-season closing chemistry.

Three Programs, One Philosophy

  • Traditional Chlorine — the 3-Step Care System — Sanitize, shock, prevent. SilkGuard Complete® tabs and sticks handle daily sanitation, Smart Shock® handles weekly oxidation and clarity, and Algae Complete® handles algae prevention. Suitable for pools of any size and surface type running 10 to 24 hours of circulation per day.
  • Salt Pools — Purpose-built chemistry for pools with a chlorine generator, including the Mineral Springs® and SaltScapes® programs. Salt pools still generate chlorine, and they still need balancing, scale protection, and cell care — these products are formulated for that specific equipment set.
  • Non-Chlorine Pools — A complete biguanide-based program for owners who want no chlorine and no bromine in the water at all, with its own dedicated sanitizer, oxidizer, and algaecide.

Formulation Technologies

Two proprietary technologies show up across the chlorine line and explain a lot of the brand's reputation. SilkGuard® Technology conditions the water so it feels noticeably softer against skin while also helping protect pool surfaces and equipment from scale. SunShield® Technology protects free chlorine from ultraviolet breakdown, which is the single largest source of chlorine loss in an outdoor pool during summer — sanitizer that survives the afternoon is sanitizer you don't have to replace.

Diagnosis, Not Guesswork

BioGuard is sold through trained specialty dealers rather than mass-market channels, and the brand backs that network with the ALEX® water analysis system. ALEX reads a full water sample — sanitizer, pH, total alkalinity, calcium hardness, cyanuric acid, metals, and more — and returns a sequenced correction plan rather than a generic product suggestion. That distinction matters more than it sounds. Cloudy water has at least six common causes, and the fix for a filtration problem is nothing like the fix for a high-pH problem or a phosphate problem. Testing tells you which one you actually have.