BioGuard Lo 'N Slo 8 lb. | pH & Alkalinity Reducer

SKU: 23477BIO
$18.99

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Description

BioGuard Lo 'N Slo is a granular pH and total alkalinity reducer built around a simple proposition: you should not have to keep a jug of muriatic acid in your garage to run a swimming pool.

Muriatic acid works. It also fumes when the cap comes off, corrodes nearby metal from across the shelf, splashes when poured, and burns skin on contact. Lo 'N Slo delivers the same correction as a dry granule that pours out of a container without a plume of vapor, doesn't attack the tools stored next to it, and doesn't turn a dropped bottle into an emergency. For most pool owners that trade is worth making on its own — before considering that the results are easier to control.

The job it does is one of the most frequently needed in pool care. pH drifts upward on its own in nearly every pool. Aeration from water features, fountains, and returns drives carbon dioxide out of the water and pushes pH up. Fresh fill water is often alkaline to begin with. Salt chlorine generators raise pH continuously as a byproduct of how they produce chlorine. Left alone, high pH means cloudy water, scale forming on surfaces and heater elements, and chlorine that tests fine but sanitizes poorly — because the higher the pH climbs, the smaller the share of your free chlorine that exists in its effective form.

Lo 'N Slo brings pH back down, and reduces total alkalinity along with it. It dissolves quickly, works in every pool type and on every surface, and swimmers can return 15 minutes after application. Dosing is organized by how high your pH actually reads, so the correction is sized to the problem rather than applied as a single generic scoop.

Pro Tip: Never add this product to a skimmer, feeder, or floater that holds chlorine tablets, and never mix it with any chlorine product. Acid and chlorine in contact release chlorine gas, which is genuinely dangerous in an enclosed skimmer housing or a storage shelf. Broadcast Lo 'N Slo over the deep end of an open pool with the pump running, keep it stored well away from your chlorine, and never combine two pool chemicals in the same bucket or scoop for any reason.

Brand

BioGuard®

What's in the Box
  • 1 x BioGuard Lo 'N Slo, 8 lb container
  • Full manufacturer label with pH-based dosing chart, first aid, and storage directions
Key Features

Lowers pH

Brings elevated pH back into the 7.4–7.6 target range, restoring sanitizer effectiveness, swimmer comfort, and protection against scale.

Reduces Total Alkalinity

Corrects high total alkalinity, which is the underlying cause of most stubborn pH problems. A pool with runaway alkalinity resists every pH adjustment you make and then drifts right back up.

Safer to Store, Transport, and Handle Than Liquid Acid

No corrosive fumes venting into your storage area, no splash risk while pouring, and no liquid to spill across a garage floor. Granular dry acid is the meaningfully safer product to keep on hand, particularly in a household with children or pets.

Quick Dissolving

Disperses rapidly with the pump running, so the correction takes effect promptly and you can retest within a reasonable window rather than waiting on an overnight cycle.

Dosing Matched to Your Reading

Three application rates keyed to actual pH ranges, so a pool at 7.8 gets a different correction than a pool at 8.5. That structure is what keeps you from overshooting into low-pH territory, which is a harder problem to walk back than the one you started with.

15-Minute Swim Return

Once the product has circulated, swimming may resume 15 minutes after application. Balancing doesn't have to cost you the afternoon.

For All Pool Types

Suitable for plaster, gunite, vinyl liner, fiberglass, and painted surfaces, in-ground and above-ground, and compatible with every common sanitizer program.

How It Works

The active ingredient is sodium bisulfate at 93.2% — commonly called dry acid or sodium acid sulfate. In dry granular form it's stable and safe to handle. The moment it dissolves, it dissociates and releases hydrogen ions into the water, which is what lowers pH. Chemically the effect is equivalent to adding acid; the difference is entirely in the handling.

Understanding what happens next explains most of the confusion pool owners have about balancing. Total alkalinity is the water's resistance to pH change. It's a measure of dissolved carbonates and bicarbonates that act as a buffer, absorbing acid and neutralizing it before pH can move. When you add Lo 'N Slo, the acid is consumed by that buffer first. Only after it has worked through some of the alkalinity does pH begin to shift.

This is why you cannot lower pH without also lowering total alkalinity. They aren't independent controls — the acid attacks the buffer on its way to changing pH. Anyone who has watched their alkalinity slide while chasing a pH reading has seen exactly this happening.

It also explains why high alkalinity is the real problem behind most persistent high-pH pools. When total alkalinity sits well above range, the buffer is so strong that pH resists correction, and then climbs straight back up afterward. Adding more acid to fight the symptom is a losing approach. Bring total alkalinity into the 125–150 ppm range first, and pH becomes far easier to hold.

There's a practical reason to care about getting this right beyond tidy numbers. Free chlorine exists in water as two species — hypochlorous acid, which does the sanitizing, and hypochlorite ion, which is dramatically weaker. The ratio between them is governed almost entirely by pH. At 7.5, a solid majority of your free chlorine is in the effective form. By 8.2, most of it isn't. Your test kit reports the same total either way, which is why a pool with high pH can read a perfect chlorine level and still go cloudy or grow algae.

One property worth noting: sodium bisulfate contributes sulfates to the water as it dissolves. In a typical residential pool with normal seasonal water replacement this is a non-issue, but sulfates accumulate the same way stabilizer does and only leave through dilution.

Pro Tip: If total alkalinity is your actual problem, there's a technique that separates the two. Instead of broadcasting, turn the pump off, let the water settle, then pour the dose slowly into one spot in the deep end and leave it undisturbed for 20 to 30 minutes. Concentrating the acid in a column drives alkalinity down harder in that area than it drives pH. Then turn the circulation back on and aerate the water — run the fountain, aim the returns upward, turn on the spa jets. Aeration raises pH without touching alkalinity. Repeat the cycle and you can walk alkalinity down into range while keeping pH where you want it. It takes a few days, but it beats the endless up-and-down of correcting one number and breaking the other.

Directions for Use

Dosage Reference

Test pH first, then dose according to your reading:

  • pH 7.7 to 8.0: 0.75 lb per 10,000 gallons
  • pH 8.1 to 8.4: 1.25 lbs per 10,000 gallons
  • pH above 8.4: 1.5 lbs per 10,000 gallons

Target Ranges

  • pH: 7.4–7.6
  • Total alkalinity: 125–150 ppm

Application

  1. Test pH and total alkalinity, and confirm your pool's actual gallon capacity before measuring.
  2. Confirm the pump and filter are running and circulating normally.
  3. Measure the correct amount using the dosage reference above.
  4. Broadcast the granules slowly over the deep end of the pool, walking the edge as you go. Do not add to the skimmer.
  5. Brush any undissolved granules off pool surfaces so they don't sit against the finish.
  6. Allow the water to circulate. Swimming may resume 15 minutes after application.
  7. Retest before adding any more. Give the pool at least four to six hours of circulation so the reading reflects the full effect of what you already added.
  8. If pH is still above range, repeat with the appropriate dose for the new reading.

Order of Operations

When correcting multiple values, work in this order — each one affects the next:

  1. Total alkalinity first. It controls how stubbornly pH resists change, so correcting pH before alkalinity means doing the job twice.
  2. pH second, once alkalinity is in range and the water will hold a correction.
  3. Calcium hardness third.
  4. Sanitizer last, in properly balanced water where it can work efficiently.

Storage and Handling

  • Store in a cool, dry, well-ventilated area away from direct sunlight and moisture
  • Keep the container tightly closed — the product cakes if it absorbs humidity
  • Store well away from chlorine products, oxidizers, and organic materials
  • Keep out of reach of children and pets
  • Never return unused product to the container once it has contacted anything else
  • Avoid breathing dust; broadcast downwind of yourself on a breezy day
  • Read and follow all label precautions, first aid, and disposal directions before use

Pro Tip: Underdose on purpose and retest. Overshooting is the expensive mistake here, not undershooting. Water below about 7.2 becomes aggressive — it etches plaster, dissolves grout, corrodes heater elements and metal fittings, and irritates eyes and skin. Correcting it means adding soda ash, which raises total alkalinity right back up and starts the cycle over. If your reading sits near the boundary between two dose ranges, take the lower one, let it circulate, and retest. You can always add more acid. You cannot take it back out.

Specifications
  • Brand: BioGuard
  • Product Type: pH reducer and total alkalinity reducer
  • Form: Quick-dissolving granular
  • Net Weight: 8 lbs
  • Manufacturer Part Number: 23477BIO
  • Active Ingredient: Sodium bisulfate, 93.2%
  • Inactive Ingredients: 6.8%
  • Common Name: Dry acid, or sodium acid sulfate
  • Dose at pH 7.7–8.0: 0.75 lb per 10,000 gallons
  • Dose at pH 8.1–8.4: 1.25 lbs per 10,000 gallons
  • Dose at pH above 8.4: 1.5 lbs per 10,000 gallons
  • Target pH: 7.4–7.6
  • Target Total Alkalinity: 125–150 ppm
  • Swim Return Time: 15 minutes
  • Application Method: Broadcast over the deep end with the pump running
  • Suitable Surfaces: Plaster, gunite, vinyl liner, fiberglass, painted
  • Sanitizer Compatibility: Chlorine, bromine, salt generator, mineral, and biguanide systems
  • Filtration Compatibility: Sand, cartridge, and DE
  • Do Not Combine With: Chlorine products or any other pool chemical
  • Not For Use In: Spas or hot tubs
  • Shipping Classification: DOT-regulated — ground shipping only
Compatibility

Pool Surfaces

  • Plaster and gunite
  • Vinyl liner
  • Fiberglass
  • Painted surfaces
  • In-ground and above-ground installations

Sanitizer Programs

  • Chlorine pools — fully compatible
  • Bromine pools — fully compatible
  • Salt chlorine generator pools — fully compatible and frequently needed, since generators push pH upward continuously as a byproduct of chlorine production
  • Mineral system pools — fully compatible
  • Biguanide (non-chlorine) pools — compatible; pH and alkalinity still require management on a biguanide program

Filtration Systems

  • Sand, cartridge, and DE filters

Critical Safety Incompatibilities

  • Never mix with chlorine products of any kind. Acid in contact with chlorine releases chlorine gas. This applies to mixing in a bucket, adding to a skimmer that holds tablets, and stacking containers where a leak could bring them together in storage.
  • Never add to a skimmer, feeder, or floater. Broadcast over the open water of the deep end with the pump running.
  • Never combine with any other pool chemical. Add products separately, allowing full circulation between each addition.
  • Add product to water — never water to product.

Other Considerations

  • Sulfate accumulation. Sodium bisulfate leaves sulfates behind, and they only come down through dilution. In pools that get heavy year-round acid demand with little water replacement, some owners prefer liquid acid for that reason. For typical seasonal residential use it isn't a practical concern.
  • Spas and hot tubs. This is a pool product sized for pool volumes. Use a spa-specific pH reducer, where dosing is scaled for a few hundred gallons.

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.