Congratulations on your new hot tub purchase from Great Bay Spa & Sauna! As you begin your journey into hot tub ownership, you may find yourself wondering about all those bottles of chemicals and what exactly they do. Don’t worry – while hot tub water chemistry might seem complex at first, it’s actually quite manageable once you understand the basics.

This guide will walk you through everything you need to know to keep your water clean, clear, and safe for everyone to enjoy. Let’s demystify hot tub chemistry and turn you into a confident spa owner!

Why Hot Tub Chemistry Matters

Unlike your bathtub that gets drained after each use, your hot tub water stays in place for months at a time. During that period, it faces a variety of challenges:

  • Body oils, lotions, and cosmetics from bathers
  • Debris from the environment
  • Bacteria growth due to warm temperatures
  • Mineral content from your source water

Proper water chemistry prevents these issues from turning your relaxing retreat into a cloudy, smelly, or even unsafe environment. When maintained correctly, your hot tub water should be crystal clear, odorless, and gentle on your skin, eyes, and equipment.

The Four Pillars of Hot Tub Water Chemistry

Hot tub water maintenance revolves around four key elements:

  1. Sanitizer levels (killing bacteria and contaminants)
  2. pH balance (water acidity/alkalinity)
  3. Total alkalinity (pH stability)
  4. Calcium hardness (water softness/hardness)

Let’s explore each of these elements and how to keep them in perfect balance.

A hot tub up close.

Sanitizers: Keeping Your Water Clean and Safe

Sanitizers are arguably the most important chemicals in your hot tub arsenal. They kill bacteria, viruses, and other microorganisms that can quickly multiply in the warm water environment.

Choosing Your Sanitizer

At Great Bay Spa & Sauna, we recommend either chlorine or bromine as your primary sanitizer. Here’s how they compare:

Chlorine:

  • Faster-acting against contaminants
  • Typically less expensive
  • More familiar to most people from pool use
  • Works best in pH range of 7.2-7.6
  • Target level: 1-3 ppm (parts per million)

Bromine:

  • Gentler on skin and eyes
  • More stable in hot water
  • Less affected by pH fluctuations
  • Remains effective longer
  • Target level: 3-5 ppm

Many of our customers prefer bromine for hot tubs because it’s more stable at high temperatures and creates fewer odors. However, chlorine remains a popular and effective choice, especially for those who are sensitive to bromine.

Adding Sanitizer to Your Hot Tub

The most effective way to add sanitizer is to:

  1. Test your current level using test strips or a liquid test kit
  2. Turn on the jets to circulate water
  3. Add the measured amount of sanitizer directly to the water
  4. Allow jets to run for 15-20 minutes to distribute evenly
  5. Test again to confirm proper level before using

Pro tip: Keep your air valves closed when adding chemicals to prevent excessive off-gassing of your sanitizer.

pH: The Foundation of Water Balance

pH measures how acidic or basic (alkaline) your water is on a scale from 0-14, with 7 being neutral. For hot tubs, the ideal pH range is 7.2-7.8, with 7.4-7.6 being the sweet spot.

Why pH Matters

  • Too low (acidic): Can corrode equipment, damage your hot tub shell, and irritate skin and eyes
  • Too high (basic): Can cause scaling, cloudy water, and reduce sanitizer effectiveness

Adjusting pH

To raise pH: Use a pH increaser (sodium carbonate) To lower pH: Use a pH decreaser (sodium bisulfate)

Always add chemicals in small amounts, wait 20-30 minutes with jets running, then retest before making additional adjustments.

Total Alkalinity: Your pH Buffer

Total alkalinity acts as a buffer that helps prevent pH from changing rapidly. Think of it as the stabilizer that keeps your pH steady even when new influences (like rain, body oils, or chemicals) enter the water.

The ideal range for total alkalinity is 80-120 ppm, with 100 ppm being optimal for most hot tubs.

Adjusting Total Alkalinity

  • To raise alkalinity: Use an alkalinity increaser (sodium bicarbonate/baking soda)
  • To lower alkalinity: Use a pH decreaser (sodium bisulfate) – the same product used to lower pH

Important: Always adjust total alkalinity before adjusting pH, as changes to alkalinity will often affect pH as well.

Calcium Hardness: Protecting Your Investment

Calcium hardness measures the amount of dissolved calcium in your water. This may seem less important than the other parameters, but balanced calcium levels protect your hot tub’s components.

The ideal range for calcium hardness is 175-250 ppm.

Why Calcium Hardness Matters

  • Too low (soft water): Can be corrosive to metal components and can etch acrylic surfaces
  • Too high (hard water): Can cause scaling on the shell, plumbing, and heating elements

Adjusting Calcium Hardness

  • To raise calcium hardness: Use a calcium hardness increaser
  • To lower calcium hardness: Partially drain and refill with softer water, or use a scale control product

Creating Your Hot Tub Chemistry Routine

Now that you understand the basics, here’s a simple routine to keep your hot tub water in perfect condition:

Weekly Maintenance

  1. Test water using test strips or a liquid test kit
  2. Adjust alkalinity if needed
  3. Adjust pH if needed
  4. Check and adjust sanitizer levels
  5. Add shock treatment (oxidizer) to eliminate contaminants

Monthly Maintenance

  1. Clean filter
  2. Test calcium hardness and adjust if necessary
  3. Add water clarifier if needed

Quarterly Maintenance

  1. Drain and clean hot tub
  2. Clean filter thoroughly or replace if needed
  3. Refill and balance all chemicals
A hot tub by a lake.

Hot Tub Chemical Shopping List for New Owners

For your convenience, here’s a starter shopping list of chemicals you’ll need:

Essential Chemicals:

  • Sanitizer (chlorine or bromine)
  • pH increaser
  • pH decreaser
  • Alkalinity increaser
  • Calcium hardness increaser
  • Non-chlorine shock/oxidizer

Testing Supplies:

  • Test strips or liquid test kit
  • Water clarifier
  • Enzymes for breaking down oils
  • Filter cleaner
  • Line flush (for when you drain the tub)

All these products are available at Great Bay Spa & Sauna, and our experienced staff can help you select the right options for your specific hot tub model.

Troubleshooting Common Water Issues

Even with regular maintenance, you may occasionally encounter water issues. Here’s how to address the most common problems:

Cloudy Water

Potential causes:

  • Low sanitizer level
  • High pH or alkalinity
  • Dirty filter
  • Organic contaminants

Solution:

  1. Test and balance water chemistry
  2. Clean or replace filter
  3. Add shock treatment
  4. Use water clarifier if needed

Foamy Water

Potential causes:

  • Body oils, lotions, or soaps
  • Low calcium hardness
  • Old water that needs changing

Solution:

  1. Use an anti-foam product for immediate relief
  2. Add enzymes to break down organic contaminants
  3. Ensure bathers shower before entering
  4. Consider draining and refilling if water is more than 3 months old

Strong Chemical Smell

Potential causes:

  • Combined chlorine (chloramines)
  • Improper pH level
  • Excessive sanitizer

Solution:

  1. Shock the water to eliminate chloramines
  2. Balance pH
  3. Allow sanitizer levels to drop if too high

Best Practices for Hot Tub Chemistry Success

To wrap up, here are some expert tips from our team at Great Bay Spa & Sauna:

  1. Test regularly: The only way to know what your water needs is to test it consistently.
  2. Shower before use: Requiring a quick rinse before entering will significantly reduce the amount of contaminants entering your water.
  3. Keep the cover on: This prevents debris from entering and reduces chemical evaporation.
  4. Add chemicals incrementally: It’s always easier to add more than to counteract too much of a chemical.
  5. Follow the order of adjustments: Always adjust alkalinity first, then pH, then sanitizer.
  6. Keep records: Note chemical readings and adjustments to spot patterns and anticipate needs.
  7. Store chemicals properly: Keep them in a cool, dry place away from children and pets.

Get Expert Help When You Need It

At Great Bay Spa & Sauna, we’re committed to helping you enjoy your hot tub ownership experience. If you ever have questions about water chemistry or encounter issues you can’t resolve, our team is just a phone call away at 1-800-436-8893.

We also offer water testing services at our Portsmouth showroom, where we can provide customized recommendations for your specific water conditions.Maintaining proper water chemistry isn’t just about protecting your investment—it’s about ensuring every soak is as relaxing and enjoyable as possible. With these basics under your belt, you’re well on your way to becoming a hot tub chemistry expert!