How To Get The Alkalinity Up In A Pool: The Definitive Balancing Guide

To raise the total alkalinity in your swimming pool, add sodium bicarbonate (pure baking soda) at a rate of 1.5 pounds per 10,000 gallons of water to achieve a 10 ppm increase. Keep your pool pump running on its highest filtration speed during and after the application to distribute the chemical, aiming for an ideal total alkalinity range of 80 to 120 parts per million (ppm).

Pre-Treatment Diagnostic & Chemical Checklist

Maintaining correct pool chemistry requires high-precision planning before any chemicals are added to the water. Total alkalinity (TA) measures the concentration of alkaline substances (primarily carbonates, bicarbonates, and hydroxides) dissolved in your water. It serves as a crucial chemical buffer, resisting rapid changes in pH.

When your total alkalinity falls below 80 ppm, the water becomes highly corrosive, leading to stained pool walls, etched plaster, corroded metal fixtures, and rapid, unpredictable swings in pH (commonly referred to as "pH bounce"). Conversely, if alkalinity exceeds 120 ppm, it can cause chronic cloudy water, calcium scale formation, and stubborn, high pH levels that resist downward adjustment.

Before attempting to modify your water chemistry, compile the necessary tools, safety gear, and testing reagents to ensure accurate dosing and safe handling.

Essential Gear, Materials, and Budget Benchmarks

• Chemical Agent: Pure Sodium Bicarbonate ($NaHCO_3$), commonly sold under commercial names like "Alkalinity Up," "Alkalinity Increaser," or as pure food-grade baking soda. Do not use sodium carbonate (soda ash) unless you intend to aggressively raise both pH and alkalinity simultaneously.
• Testing Equipment: A high-quality liquid reagent test kit (FAS-DPD kit) utilizing Taylor R-0007, R-0008, and R-0009 reagents. Avoid paper test strips, as they lack the precision required for exact PPM dosing calculations.
• Safety Equipment: Chemical-resistant safety goggles, heavy-duty nitrile gloves, and closed-toe shoes.
• Mixing Tool: A clean, chemical-safe 5-gallon plastic bucket and a plastic stirring rod.
• Measurement Tools: A digital scale calibrated in pounds and ounces, or a dedicated dry chemical measuring cup.
• Estimated Budget: $20 to $60, depending on pool volume and the volume of sodium bicarbonate required.
• Time Commitment: 30 minutes of active labor; 6 to 24 hours of circulation and stabilization time.

Step-by-Step Pool Alkalinity Adjustment Workflow

Follow this precise clinical workflow to calculate, dose, and apply sodium bicarbonate to your pool without causing chemical scale precipitation or cloudiness.

Step 1: Calculate Your Pool's True Water Volume

To avoid over-dosing, you must know your pool's exact gallonage. If you do not have the original construction documents, use these standard geometric formulas:

• Rectangular Pools: Length (ft) x Width (ft) x Average Depth (ft) x 7.5 = Total Gallons
• Circular Pools: Diameter (ft) x Diameter (ft) x Average Depth (ft) x 5.9 = Total Gallons
• Oval Pools: Long Axis (ft) x Short Axis (ft) x Average Depth (ft) x 6.7 = Total Gallons
• Freeform Pools: Divide the pool into geometric zones (rectangles/circles), calculate each zone's volume, and sum them.

Step 2: Establish Your Baseline Water Metrics

Test your pool water away from the return jets. Submerge your testing comparator tube elbow-deep (approximately 18 inches below the surface) to get a representative sample.

1. Run the total alkalinity test: Add 5 drops of chlorine neutralizer (R-0007), 5 drops of indicator reagent (R-0008), then swirl. The water will turn green.
2. Drop-count with acid reagent (R-0009), swirling after each drop, until the color transitions from green to a stable light pink/red.
3. Multiply the drop count by 10 to determine your baseline TA in parts per million (ppm).
4. Measure your current pH. The ideal range is 7.2 to 7.6.

Pro-Tip: If your sanitizing chemical is Trichlor tabs (which are highly acidic with a pH of ~2.8), aim for a higher baseline target of 100 to 120 ppm of alkalinity to counteract the acid. If you use liquid chlorine or calcium hypochlorite (which are basic), an alkalinity target of 80 to 90 ppm is preferred.

Step 3: Determine Your Total Chemical Demand

Calculate your exact chemical requirement using the standard industrial dosing metric: 1.5 pounds of sodium bicarbonate will raise the total alkalinity of 10,000 gallons of water by 10 ppm.

For example, if your 20,000-gallon pool currently tests at 60 ppm and your target is 90 ppm (a 30 ppm increase):

1. Determine the multiplier for your volume: 20,000 gallons / 10,000 gallons = 2.0.
2. Determine the multiplier for your target increase: 30 ppm / 10 ppm = 3.0.
3. Multiply these factors together with the baseline dosage: 1.5 lbs x 2.0 x 3.0 = 9.0 pounds of sodium bicarbonate.

Warning: Never add more than 10 pounds of sodium bicarbonate per 10,000 gallons of pool water in a single 24-hour window. Excessively rapid changes to the water matrix can trigger a high-pH environment locally, causing calcium to precipitate out of solution, leading to a cloudy pool and filter scaling.

Step 4: Slurry or Broadcast the Chemical Application

To ensure even dissolution and avoid chemical settling on plaster or vinyl surfaces:

1. Turn on the pool's primary filtration pump to its maximum speed setting. Ensure the main drain valves are open to pull water from the bottom of the pool.
2. If your pool has a vinyl liner, fiberglass shell, or painted finish, pre-dissolve the sodium bicarbonate. Fill a 5-gallon bucket 3/4 full with pool water, add up to 2 pounds of sodium bicarbonate, and stir thoroughly with a plastic rod until completely dissolved.
3. Walk the perimeter of the deep end of your pool and slowly pour the mixture directly into the water. Avoid pouring directly into the skimmer, as high chemical concentrations can damage internal pool equipment, heat exchangers, or chlorinators.
4. If you have a plaster or gunite pool, you can broadcast the dry powder directly over the deep-end surface on a calm day, brushing any undissolved powder off the floor immediately using a nylon pool brush.

Step 5: Circulate, Stabilize, and Re-Evaluate

Leave the pool pump running continuously for at least 6 to 8 hours to ensure complete molecular integration throughout the water column. Do not allow swimming for at least 4 hours after application to prevent skin or eye irritation from undissolved chemical pockets.

Retest the total alkalinity and pH after 24 hours of continuous circulation. If the target level has not been fully realized, repeat the calculation and application steps.

Chemical Dosing and Water Chemistry Targets

The table below outlines the precise amount of sodium bicarbonate required to raise total alkalinity by desired increments across various common residential pool volumes.

Water Balance Complications & Corrections

During pool chemistry balancing, unexpected chemical interactions can occur. Use these real-world scenarios to troubleshoot and correct water balance anomalies safely.

Scenario 1: The Water Turned Milky and Cloudy Post-Addition

• Root Cause: The sodium bicarbonate was added too quickly or in too high a concentration, causing a localized surge in pH. This localized high pH combined with high Calcium Hardness levels (above 400 ppm), forcing calcium carbonate out of solution as a visible, suspended precipitate.
• Actionable Fix: Run your pool filtration system continuously for 24 to 48 hours. Clean or backwash your filter daily to remove captured calcium scale. If the cloudiness persists after 48 hours, measure your pH. If the pH has spiked above 7.8, add small, calculated doses of muriatic acid (hydrochloric acid) to lower the pH back to 7.4, which will help dissolve the suspended calcium carbonate back into its ionic state.

Scenario 2: Total Alkalinity Rose, but pH Spiked Excessively High (Above 8.0)

• Root Cause: You utilized sodium carbonate (soda ash) instead of sodium bicarbonate, or your pool water was aggressively aerated (via waterfalls, deck jets, or water slides) during the balancing process. Aeration drives carbon dioxide out of the water, which naturally forces pH levels upward without affecting alkalinity.
• Actionable Fix: Add muriatic acid to lower the pH. To lower pH without significantly dropping your newly adjusted alkalinity, add dilute muriatic acid around the deep end perimeter while the pump is running. Retest after 4 hours of circulation.

Scenario 3: Total Alkalinity Drops Back Down Rapidly Within Days

• Root Cause: The regular sanitizer being used is highly acidic, or the pool has experienced heavy, acidic rainfall. Additionally, if you have been adding excessive amounts of dry acid (sodium bisulfate) or muriatic acid to lower pH, it will continuously consume your alkalinity buffer.
• Actionable Fix: Transition your primary sanitizer away from acidic Trichlor pucks to neutral or basic alternatives like liquid chlorine (sodium hypochlorite) for several weeks. Check the chemical balance of your source water (tap or well water) to ensure you are not introducing highly acidic water during top-offs.

Frequently Asked Questions

Can I use ordinary grocery store baking soda to raise my pool's alkalinity?

Yes. Grocery store baking soda is 100% pure sodium bicarbonate, which is chemically identical to the "alkalinity increaser" sold at specialty pool supply stores. Using grocery store baking soda is highly effective and often more economical when purchased in bulk.

Should I raise my pool's alkalinity or pH first?

Always adjust and balance your total alkalinity before adjusting your pH. Because alkalinity acts as a chemical buffer for your pH level, trying to adjust pH first in water with low alkalinity will result in erratic pH swings and highly inefficient chemical usage.

How long must I wait to swim after adding sodium bicarbonate?

You should wait at least 4 hours after adding sodium bicarbonate before allowing anyone to swim. This ensures the chemical has completely dissolved and circulated evenly throughout the entire volume of your pool, avoiding localized areas of high concentration.

What is the difference between sodium bicarbonate and soda ash?

Sodium bicarbonate ($NaHCO_3$) is used to significantly raise total alkalinity while causing only a minimal, gentle upward shift in pH. Soda ash ($Na_2CO_3$) is highly basic and is used to aggressively raise pH, though it will also raise total alkalinity to a lesser degree.

Maintain Perfect Water Chemistry All Season

Protect your pool equipment and enjoy crystal-clear water by monitoring your chemical balance weekly. For professional-grade pool chemicals and advanced testing supplies, visit your local authorized pool supply dealer today.