BioGuard Spot Kill | Green & Black Algae Killer
Excluded Brands
The following brands are not eligible for LTI discount codes (including WELCOME). They go on sale only during manufacturer-authorized promotions:
- Gozney — pizza ovens and accessories
- OHCO — massage chairs
- Positive Posture — massage chairs and recliners
- Nomadix — outdoor lifestyle products (towels, blankets, accessories)
Excluded Products
The following individual products are also not eligible for discount codes:
- Any product that already has a price markdown — items on sale or clearance can't stack additional discounts on top
- FreshWater Salt System Replacement Cartridge (single)
- FreshWater Salt System Replacement Cartridge (3 Pack)
- Route Protection Insurance — third-party shipping protection, not eligible for our discounts
- Bullfrog A / R / X Series 10-00282 Filter Cartridges
- Bullfrog STIL Series 10-00281 Filter Cartridges
- FROG® @ease Sanitizer System for Bullfrog Spas
- FROG® @ease Replacement Cartridge for Bullfrog Spas (3 Pack)
- Bullfrog Simplicityâ„¢ Flat Filters for M Series (4 Pack)
- Filter Core Cage & Cap Assembly for Bullfrog Spas
- Fireplaces (gas, wood-burning, and fireplace inserts)
- Electric Fireplaces
- Gas Vent Pipe
- Pellet Vent Pipe
- Fireplace Fronts
This list can change. Manufacturers occasionally add or remove products from their MAP-protected lists. We update this page when they do, but the most accurate way to confirm whether a discount applies to a specific item is to add the item to your cart and try the code at checkout. If the code doesn't work, the item is excluded. If it does work, it's eligible.
Returns On Hazardous Materials
Some of the products we sell — primarily spa and pool chemicals — are classified as hazardous materials by the U.S. Department of Transportation (DOT). These items can't be returned to us by mail, even though we'd like to make returns easy on every product. This page explains why the rule exists, what's covered, and what your options are if you have unopened chemicals you no longer need.
The short version: We can't accept hazmat returns by mail (federal regulations prohibit it), but we can accept them in person at our Idaho Falls, Boise, or Twin Falls showrooms. If a product arrived damaged or defective, that's handled differently — call us right away and we'll work with the manufacturer on a replacement or refund.
BioGuard Spot Kill is a fast-acting granular treatment for killing algae that's already growing — including black algae, the most stubborn variety a pool owner will ever face. It's a corrective product, not a preventative, and it's meant to be applied directly onto the growth rather than dosed across the pool as routine maintenance.
The chemistry is 99% sodium dichloro-s-triazinetrione dihydrate — highly concentrated stabilized chlorine, applied at heavy algae-killing rates rather than sanitizing rates. That matters for two reasons. First, it means the product works by overwhelming algae with oxidizing chlorine, which is genuinely effective against growth that resists ordinary sanitizer levels. Second, it means Spot Kill is not an algaecide in the usual sense — it doesn't leave a preventative residual, and it does add cyanuric acid to your water.
What makes it well suited to spot treatment is solubility and surface safety. The formula is highly soluble and near pH neutral, so a concentrated application over a patch of black algae on a step or behind a ladder dissolves quickly rather than sitting as a caustic pile against the finish, and it doesn't swing your balance the way a strongly acidic or alkaline product would. It's approved for vinyl, painted, fiberglass, and colored plaster pools — the surfaces most easily damaged by aggressive chlorine.
Black algae is the reason this product exists. It anchors roots into plaster and grout and grows a waxy protective layer that ordinary chlorine simply can't penetrate. Killing it requires physically breaking that layer open with a brush and then delivering a heavy concentration of oxidizer directly to the exposed colony. That's exactly the sequence Spot Kill's directions describe, and it's why brushing isn't optional here.
Pro Tip: Brush first, and brush hard. Black algae grows a protective outer layer and sends roots into plaster and grout, and chemistry applied to an undisturbed colony largely runs off the top of it. That's the single most common reason a black algae treatment "doesn't work." Scrub the affected areas thoroughly before you apply — use a stainless brush on plaster and gunite, or a stiff nylon brush on vinyl, painted, and fiberglass surfaces where steel would damage the finish. Pay particular attention to pool steps, ladder steps, and the areas around the skimmer and lights, which is where black algae almost always establishes first.
BioGuard®
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.
