BioGuard SoftSwim B | Biguanide Pool Sanitizer

• 1 x BioGuard SoftSwim B, 64 oz (1/2 gallon) bottle
• Full manufacturer label with start-up and maintenance dosing and safety information

One 64 oz bottle is exactly one full start-up dose for a 10,000-gallon pool. Size your order accordingly — a 20,000-gallon pool needs two bottles just to reach 50 ppm.

Step B of the SoftSwim Program

The sanitizer that does the actual disinfecting — killing and controlling harmful bacteria without chlorine or bromine anywhere in the water.

Gentle on Eyes, Hair, and Skin

No chlorine smell, no stinging eyes, no dried-out skin, and no bleached swimwear. This is the reason most people switch to SoftSwim and stay on it.

Polymeric Action Attracts Contaminants

Gathers suspended material into larger masses the filter can actually capture, contributing to the clarity SoftSwim pools are known for.

Effective Over a Wide pH Range

Doesn't lose most of its effectiveness as pH drifts upward the way chlorine does, so balance swings are far less punishing on a biguanide program.

Non-Staining and Non-Corrosive

Biguanide isn't an oxidizer, so it doesn't attack metal fittings, heater components, or pool surfaces, and it leaves no staining behind.

Stable in Sunlight

UV-shielded and resistant to evaporation, so the residual holds through hot, bright weather instead of burning off each afternoon.

No Stabilizer Required

Because biguanide doesn't need cyanuric acid protection, there's no stabilizer accumulating permanently in the pool and no mid-season stabilizer lock to manage.

Long-Lasting Residual

The 50 ppm target holds far longer than a chlorine residual does, so maintenance is measured in weekly checks and occasional top-ups rather than daily dosing.

The active ingredient is polyhexamethylene biguanide hydrochloride — PHMB — at 20%, in a solution of roughly pH 7.5. It's a polymer, which is the key to understanding everything the product does.

PHMB kills bacteria by attacking the cell membrane directly. The polymer carries a positive charge distributed along its length, and bacterial cell membranes are negatively charged, so the molecule binds to the membrane and disrupts its structure until the cell can no longer maintain itself. That's a physical mechanism, not an oxidative one, and the distinction explains nearly every difference between biguanide and chlorine.

Chlorine sanitizes by oxidation — it destroys contaminants by stripping electrons from them. That's powerful and fast, but it means chlorine is consumed by everything it touches: bacteria, sweat, sunscreen, leaves, and ultraviolet light all use it up. That's why a chlorine pool needs constant replenishment and why the residual crashes after a busy weekend.

PHMB isn't consumed the same way. It isn't spent oxidizing organic waste, it doesn't break down under UV, and it doesn't lose activity at high temperature. The residual depletes slowly, mostly through dilution from rain and splash-out and through removal at the filter. That's why the target is 50 ppm rather than 3 ppm — you're maintaining a durable standing concentration instead of constantly replacing a residual that keeps disappearing.

The same polymer chemistry produces the contaminant-attracting action. Long charged polymer chains bridge between suspended particles, pulling them into clusters large enough for the filter to remove rather than pass through.

The tradeoff is that PHMB is a strong bactericide but a weak algaecide and no oxidizer at all. That's exactly why the program needs all three steps: SoftSwim A handles algae, this product handles bacteria, and SoftSwim C handles the body oils, cosmetics, and organic waste that chlorine would otherwise burn off. Skip any one and the system doesn't hold.

It also explains the chlorine conflict directly. Chlorine is an oxidizer, and PHMB polymer chains are readily oxidized. Introduce chlorine and it destroys the sanitizer while the reaction products form a sticky residue that fouls filter media. Both chemicals are consumed and the pool is left with no sanitizer at all.

Pro Tip: Buy SoftSwim test strips at the same time as the sanitizer, because nothing else will read this pool. A standard chlorine or bromine test kit measures a halogen residual, and a SoftSwim pool has none — the strip will show essentially zero while the pool is perfectly sanitized at 50 ppm. That mismatch causes real problems: people assume the pool is unsanitized and reach for shock, which is the single worst thing they could add. Test weekly with the correct strips, and if you ever take a sample in for testing, say SoftSwim or biguanide before it goes in the machine.

Dosage Reference

• Start-up: 1/2 gallon (64 oz) per 10,000 gallons — establishes 50 ppm
• Maintenance top-up: 1 pint (16 oz) per 10,000 gallons — raises the level approximately 10 ppm
• Target concentration: approximately 50 ppm
• Minimum concentration: never below 30 ppm
• Target pH: 7.2–7.8

Start-Up — Freshly Filled and Dechlorinated Pools

1. If the pool water contains algae or is hazy, consult "The Pool Care Guide for SoftSwim," available from your authorized BioGuard dealer, before proceeding.
2. Backwash or chemically clean the pool filter.
3. Check pool pH and adjust to 7.2–7.8 if necessary.
4. Add SoftSwim B to give a content of 50 ppm — 1/2 gallon of product per 10,000 gallons of pool water.
5. After 24 hours, check pH and SoftSwim B concentration with the appropriate test kit and adjust if necessary.
6. Add SoftSwim A and SoftSwim C per their own label directions to complete the program.

Routine Maintenance

1. Every week, check SoftSwim B concentration and pH.
2. Maintain SoftSwim B concentration at approximately 50 ppm.
3. If the concentration has fallen by 10 ppm or more, add a top-up dose: 1 pint per 10,000 gallons raises the level about 10 ppm.
4. Never allow the level to drop below 30 ppm.
5. Keep pH in the 7.2–7.8 range.
6. Run circulation at least 12 hours per day throughout the season.
7. Maintain SoftSwim A and SoftSwim C on their own schedules.

Converting from a Chlorine Pool

SoftSwim start-up directions specify a freshly filled and dechlorinated pool. The two chemistries cannot be blended or transitioned gradually, so converting from chlorine or bromine is a defined process, not simply switching products. Talk to your authorized BioGuard dealer before you begin — the correct approach depends on your current sanitizer level, stabilizer level, and filter type.

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 well away from any chlorine or bromine products — a leaking container of either could ruin both
• Keep out of reach of children and pets
• Read and follow all label precautions, first aid, and disposal directions before use

Pro Tip: Do the math before you order, because the start-up dose is larger than most people expect. This 64 oz bottle is a half gallon, which is exactly one start-up dose for a 10,000-gallon pool. A 15,000-gallon pool needs a bottle and a half; a 20,000-gallon pool needs two full bottles to reach 50 ppm on the initial fill. Maintenance is much lighter — a pint per 10,000 gallons per 10 ppm of correction — but plan the opening order around your actual pool volume. These are hazmat items that ship ground only, so running short mid-startup means waiting on a second delivery with an unsanitized pool.

• Brand: BioGuard
• Product Type: Biguanide pool sanitizer and bactericide
• Form: Liquid
• Volume: 64 oz (1/2 gallon)
• Manufacturer Part Number: 22852BIO
• Active Ingredient: Polyhexamethylene biguanide hydrochloride (PHMB), 20%
• Product pH: Approximately 7.5
• Chlorine Content: None
• Bromine Content: None
• Stabilizer Required: None
• Start-Up Dose: 1/2 gallon per 10,000 gallons, giving 50 ppm
• Maintenance Dose: 1 pint per 10,000 gallons raises the level approximately 10 ppm
• Target Concentration: Approximately 50 ppm
• Minimum Concentration: 30 ppm
• Target pH: 7.2–7.8
• pH Tolerance: Effective over a wide pH range
• UV Stability: UV-shielded; resistant to evaporation in sunlight
• Surface Effects: Non-staining and non-corrosive
• Testing Requirement: SoftSwim-specific test strips — chlorine test kits will not read this pool
• System Role: Step B of the BioGuard SoftSwim program
• Required Companion Products: SoftSwim A algaecide and SoftSwim C clarifier
• Program Pool Limit: Less than 25,000 gallons, with a bottom drain and 12+ hours daily circulation
• Not Compatible With: Chlorine, bromine, salt chlorine generators, or mineral systems
• Shipping Classification: DOT-regulated — ground shipping only

The SoftSwim A-B-C System

• SoftSwim A — algaecide; carries the full algae-control load, since biguanide is a weak algaecide.
• SoftSwim B — bactericide; the biguanide sanitizer. This product.
• SoftSwim C — clarifier; removes body oils, cosmetics, and organic contaminants the sanitizer doesn't address.

All three are required. SoftSwim B is a sanitizer only and cannot run a pool by itself.

Pool Requirements for the SoftSwim Program

• In-ground or above-ground pools holding less than 25,000 gallons
• Pools that have a bottom drain
• Pools with excellent circulation, with the pump operating at least 12 hours per day

Critical Incompatibilities

• Chlorine, in any form. No tablets, granules, liquid chlorine, shock, or chlorine-based algaecide. SoftSwim B and chlorine are chemically incompatible and destroy each other.
• Bromine, in any form. Same conflict.
• Saltwater chlorine generators. A salt system manufactures chlorine, making it fundamentally incompatible.
• Mineral sanitizer systems. Not for use alongside mineral-based programs.
• Non-chlorine shock formulated for chlorine pools. Confirm any oxidizer is labeled for biguanide systems before adding it.
• Never mix with any other chemical in a bucket, skimmer, or feeder. Add products separately with circulation between additions.

If Accidental Chlorination Occurs

If chlorine reaches the pool by accident, stop adding anything else and consult your authorized BioGuard dealer before taking action. Do not attempt to correct it by adding more chlorine or more SoftSwim B. The right response depends on how much chlorine entered and how far the sanitizer has been degraded, and guessing usually makes the recovery more expensive.

Testing

Requires SoftSwim-specific test strips. Chlorine and bromine test kits cannot measure a biguanide residual and will read near zero in a properly sanitized SoftSwim pool.

Filtration Notes

Biguanide programs tend to accumulate a residue in filter media over time, so plan on cleaning the filter more often than a chlorine pool would need. Use a filter cleaner appropriate to your media, and never allow filter cleaner to return to the pool.