Hot Tub Chemicals 101: What You Actually Need

If you’ve just bought your first hot tub, you’re probably excited to jump in. But before you do, there’s one big step you can’t skip: water care. The world of spa chemicals can feel overwhelming, but the truth is, you only need a few key ones to keep your water clean, safe, and relaxing.

Why Hot Tub Chemicals Matter

Hot tub water might look fine at first, but without proper treatment, it quickly turns into a breeding ground for bacteria, algae, and grime. Chemicals help keep your water:

• Clean and sanitized

• Safe for skin and eyes

• Free from cloudy buildup or odors

• Balanced so your equipment lasts longer

The Core Chemicals You Actually Need

Let’s break it down to the must-haves. You don’t need every bottle on the store shelf. Start with these:

1. Sanitizer

This is the most important chemical in your hot tub. It kills bacteria and keeps your water safe.

• Options: Chlorine or bromine

• Tip: Bromine is gentler on skin and lasts longer in hot water.

2. pH Increaser and Decreaser

Your water’s pH should stay between 7.4 and 7.6. If it’s too high or low, it can cause irritation, damage your spa, or reduce sanitizer effectiveness.

• Raise with: Sodium carbonate (pH increaser)

• Lower with: Sodium bisulfate (pH decreaser)

3. Alkalinity Increaser

Alkalinity acts as a buffer to keep pH stable. Aim for 80 to 120 ppm.

• Common product: Sodium bicarbonate (baking soda)

4. Shock

Shock breaks down organic contaminants like body oils and leftover sanitizer. It keeps your water clear and helps your main sanitizer work better.

• Types: Chlorine shock or non-chlorine shock

• When to use: After heavy use or weekly

5. Calcium Hardness Increaser

Low calcium can corrode your hot tub’s parts. Too high, and it creates scale.

• Ideal level: 150 to 250 ppm

• Fix with: Calcium hardness increaser

Optional Chemicals You Might Need

These aren’t required for everyone but can be helpful depending on your local water or spa habits:

• Clarifier: Helps filter out tiny particles

• Enzyme cleaner: Breaks down oils and scum

• Foam reducer: Stops bubbles caused by lotions or detergents

• Stain and scale preventer: Helps with hard water or metals

How to Add Chemicals the Right Way

• Step 1: Test your water using test strips or a kit.

• Step 2: Turn on your jets for circulation.

• Step 3: Add one chemical at a time and wait at least 30 minutes between additions.

• Step 4: Retest before adding more.

Beginner Mistakes to Avoid

• Guessing doses. Always measure properly.

• Skipping shock. This one is easy to forget but crucial.

• Ignoring pH and alkalinity. Balance these first.

• Adding all chemicals at once. Go slow and steady.

How to Build a Simple Chemical Routine

To make things easy, build a basic habit:

• Test your water 2 to 3 times a week

• Add sanitizer as needed

• Shock your hot tub weekly

• Balance pH and alkalinity right away

• Drain and refill every 3 to 4 months

Taking care of your hot tub doesn’t have to be complicated. Stick to the essentials, follow a consistent routine, and you’ll have clean, safe water without the stress.