Why Does Hot Tub Water Need to Be Hard?

Do You Need To Shock An Ozone Pool?

Why Does Hot Tub Water Need to Be Hard?

1. Better Water Clarity

They design hot tub chemicals to detoxify the water and kill algae, leaving behind a harmless layer of calcium carbonate.

This layer helps prevent chloramines from forming as you swim in the hot tub, which is said to provide clearer and better-tasting water.

2. Protection Against Corrosion of Metal Parts

Most hot tubs are made with metal walls and a metal shell. When some chemicals are in the water for long periods, they can react with the metals and leave behind a film or residue. The calcium carbonate layer helps to protect these parts from corrosion by acting as a barrier.

3. Prevention of Bacterial Growth

The chemicals that keep your hot tub sparkling white also prevent bacteria from growing. This prevents the growth of biofilm.

The calcium carbonate in the water works as an anti-biofilm agent because it is not porous enough for bacteria to adhere.

4. Enhanced Heat Retention

The calcium carbonate layer also helps to enhance the heat retention capabilities of your hot tub.

This is because it is a less dense substance than water and has a greater thermal mass. It will take longer for the temperature of your hot tub to change.

This can be beneficial during the summer months when your hot tub gets lots of use, and you may want to run it overnight to enable the chlorine enough time to dissipate so that you can go through with a hot tub session in the morning.

5. Less Water Consumption

When you are using chemicals to keep your hot tub sparkling white, there is a chance that you will lose chlorine and other water-soluble chemicals from the water.

This may not seem like a big deal, but it is. When this happens, the calcium carbonate layer acts as an anti-corrosion agent and helps to protect your hot tub from rusting in general. 

Can I Fill My Hot Tub with Softened Water?

This is the water that has a lower mineral content, generally through softening salts. You can determine water hardness by the level of calcium and magnesium in the water.

Softened water typically contains less than 0.5 parts of magnesium and calcium per million parts (ppm).

Do I Need to Backwash After Vacuuming?

Yes! Yes, you can fill your hot tub with softened water, but remember essential considerations.

  1. You need to use softened water that you have already run through a filter. This will get rid of things like chlorine, which can be irritating to the skin and eyes.
  2. You should clean your hot tub cover as soon as possible since softened water will harm it if it stays wet too long.
  3. You should avoid using any oil soap because this can sometimes make soap films that are difficult to clean off and can clog the filter.
  4. You should make sure that you clean your hot tub cover and filter once a year, no matter what you use it with.
  5. If your Spa water gets silty, backwash your filter more often until the water is clear again. This is because softened water will cause the filter to build up much faster than it usually would if you were using normal hard water.

To clean the filter more quickly, turn it off for a few hours (or overnight if possible) and then backwash it when you turn it back on.

  • If you keep your hot tub in a shady area, add some algaecide to the water weekly. This will help prevent algae from growing in your water and make it easier to clean the cover. 

Why Can Hard Water or Soft Water Be Bad For My Hot Tub?

FactorHard WaterSoft water
Mineral BuildupIt will deposit minerals in the hot tub -This can cause problems, such as a low pH level and scale.

Often more appropriate for Spas because it’s less likely to heat up and cause problems with algae in the hard water.
It will not deposit any minerals in the hot tub, which can cause corrosion of metal parts.

It may be more appropriate for showers, bathtubs, and other small loads.
PH BalanceCan cause the pH level inside your hot tub to be low-This, can cause problems with the hot tub’s sanitizer and other chemicals.Can have a high pH level-It will deposit calcium and other minerals, which will cause scale inside your hot tub.
Chemical ReactionsCan cause chemical reactions in your hot tub -This can occur when you add sanitizers or when you use chemicals.Will not cause reactions like this-It will be easier to sanitize and clean your hot tub with soft water.
Equipment DamageWill cause damage to hot tub parts-This happens because minerals can build up inside the hard water.Will not cause the same kind of damage to your hot tub -It is easy to clean and sanitize a soft water hot tub.
Algae BuildupMay contain chemicals that algae need to grow-This can cause an algae buildup in your hot tub.Will not have any of those chemicals, which means an algae buildup is much less likely.
CostWill cost you more in sanitizers, chemicals, and other things-This is because hard water can cause problems like scale and a low pH level.Will cost less to maintain-It’s easier to control the pH level with soft water because it won’t deposit any minerals.

When Should You Bypass a Water Softener?

Initial Fill UpIf you want to start fresh, de-ionizing water is an excellent place.
Draining And RefillingAfter filling it up, the salt in your tank makes it hard for water to move through the system.
Chemical TreatmentWhen adding chemicals to your hot tub, bypass the water softener to avoid any potential chemical reactions with the softened water.
The Quality Of The WaterIf you notice that the water from the tub leaves white residue on everything, it’s time to backflush your softener.

Saltwater will eventually cause corrosion in pipes and pump motors, so you are advised to bypass when not in use.

This will also prevent any overflow of cleaners, oils, or lotions from contacting your hot tub and causing a chemical reaction with the softened water.
MaintenanceIf you’re going to have your hot tub drained, this is the time to bypass the softener.
Water Quality IssuesIf your hot tub is getting very hard and you’re having trouble with it (water coming out pretty clear but not getting to the heater), bypassing the softener is also a good time.

What To Do Before Filling the Hot Tub With Water?

Before filling a hot tub with water, here are some steps that you should take:

1. Check the hot tub for any damage: Inspect it for any damage before filling it with water. If you notice cracks, leaks, or damage to the shell, do not fill it with water.

2. Maintain proper water levels: Before filling a hot tub with water, ensure there are enough water levels in the hot tub and that you will not have to add water to it in short intervals of 2 hours or less.

Why Does Hot Tub Water Need to Be Hard?

The general rule of thumb is to have approximately 3 inches of water in the hot tub before using it for the first time. Also, remember to check your hot tub’s temperature often while using it.

3. Test the chemicals: Before filling a hot tub with water, ensure you test the hot tub’s chemicals. You should test the hot tub for pH, chlorine, and total alkalinity.

Your local pool supply store is great for buying all the items needed to maintain your hot tub.

4. Get rid of debris: Before filling a hot tub with water, remove any debris that may have gathered around your hot tub.

You may need to brush or hose down the hot tub to remove any loose dirt, sticks, or other debris. This will help prevent clogs and other problems in the future.

5. Clean the water lines: Before filling a hot tub with water, clean the water lines with a cleaning solution recommended by your local pool supply store to prevent from getting scale buildup in the future.

You can find water line cleaners at any local pool supply store.

6. Check for leaks: Before filling a hot tub with water, check for any leaks or other possible problems affecting your hot tub. If you find any problems, call a professional to repair the area before filling the hot tub with water.

Will My Water Softener Regenerate If I Bypass It?

Purchase a Bypass valve from a Hardware store or onlineThis bypass valve is fitted with a stainless-steel screen, which helps prevent debris from clogging the softener.

Take off your old bypass valve and replace it with this new one.
Unscrew the Old valve and put it aside for use in your softenerOnce you have done, screw on the new bypass valve.
Place a bucket under the old valveThe water will start to drain from the top of the softener; it may take some time, depending on how much water there is in it.
Remove the screen from the new bypass valve, and insert it into a hole on the top of your softenerThe screen will stop any solid pieces of material from going through to the softener.
Insert the bypass valve into your water softener, making sure that you have screwed it in properlyScrew the original valve in at this point.
Enjoy your softened water without having to run the softenerThe screen on your bypass valve will prevent big pieces of debris from clogging up the softener, meaning that you don’t have to spend as much time cleaning it.

What Happens When You Let Water Softener Run Without Salt?

Increased Water HardnessLead and copper deposits and Scale formation occurs.
Decreased Water QualityMore sediment in pipes, Plasticizer leaches out of PVC materials, causing Crosslinks to form.
Reduced Water FlowWeirs and pipes become clogged with scale, Water hammer occurs, causing loss of pressure to fixture.
Increased Energy ConsumptionEnergy needed for high-pressure pump to flush out residue, Increased water needs (ex: more stains).
Damage To the SoftenerPumps overheat, causing a breakdown, Pumps break down due to internal erosion ,Pumps fail due to damage from high water pressure.

What Do You Add to A Hot Tub When Refilling?

What to AddPurposeAmount
ChlorineTo kill bacteria1-2 tablets for every 100 gallons of water.
AlcoholTo kill bacteria and fungus5% solution for every 100 gallons of water.
Sodium ChlorideTo neutralize the acidity and keep chlorine from eating away at metals in the tub.1/8 teaspoon per gallon of chlorine.
Stain and Scale PreventerTo prevent scale and staining.2 tablespoons per 100 gallons of water.
BoraxTo reduce scale, hardness, and dissolved metals in the water.1/4 teaspoon per gallon of chlorine.
Seltzer Water (club soda)To remove burned-on oils from the tub.Fill the hot tub until it overflows into a bucket.
Water Softener (optional)To soften water in an outdoor tub, e.g., saltwater pools.1 cup per 100 gallons of water.
Shock treatmentTo kill bacteria in a hot tub.1 tablespoon per 100 gallons of water.
pH AdjustersTo lower the pH if it is too high.According to instructions on the bottle.

How To Combat Soft Water Issues in Hot Tubs

Skin IrritationCheck for high levels of sanitizer or pH imbalances and adjust as needed.
Rinse jets with warm water every day.

Wet skin when getting out to avoid chafing.
Do not use soap on the skin or in water.
Foamy WaterCheck for high levels of sanitizer or pH imbalances and adjust as needed
Check plumbing to ensure proper flow.

Check your filter and replace it if necessary.
Let the water balance; don’t run full jets for long periods.
Do not use soap on the skin or in water.
Calcium BuildupCheck plumbing to ensure proper flow.
Check your filter and replace it if necessary.

A power washer (available at big box home improvement stores) is often effective. Do not use as a regular cleaning method, only for calcium buildups.
Algae ProblemsCheck plumbing to ensure proper flow.

Check the filter and replace it if necessary.
Regular hot tub maintenance (cleaning, water balance).
Low Water LevelsCheck plumbing to ensure proper flow.
Check the filter and replace it if necessary.

Do not use water from pools, spas, fountains, ponds, or lakes.
White “Scum” On The Sides Or Bottom Of The TubCheck for high levels of sanitizer and adjust as needed.

Water sitting in a hot tub for a long time can cause this problem, drain and refill after it sits for extended periods.

What Happens If Hot Tub Water Is Too Soft?

Corrosion-Corrode your heater.
– Poison the bacteria causing corrosion.
– Corrode your pump.
Raise The PH Of Your Water-Cause skin irritation and other problems for people in the hot tub.
Foaming-Cause foam deposits and odors.
– Cause skin irritation and other problems for people in the hot tub.
Cloudiness-Cloud your water.
– Cause skin, eye, and other problems for people in the hot tub.
Odor-Cause smells, organic materials, and bacteria to start growing in your hot tub.
– Causes you to run your heater more often as a constant addition of chemicals (chlorine) and use more chemicals (chlorine) to keep the smell down.
Watercolor Change-Causes dirty water in your hot tub.
Skin Irritation-Cause skin irritation.
– Cause eye irritation.
– Make you sick after using your hot tub.
Hair Loss And Dry Skin-Cause hair to fall out.
– Cause dry skin and chapping.

Why Does My Hot Tub Water Feel Silky?

ChemicalsBromine, Chlorine, Sulfur and Calcium.
MineralsSodium, Magnesium, Potassium.

Calcium and Magnesium mix to create a silky feel in the water. These minerals are also known as “softeners” because they soften the water.

Soft water feels silkier, while hard water feels harsher on skin and clothing.
Water softeners/conditionersSalt, Soap, Calcium and Magnesium “crystals.”
Some detergents

Copper pipes (softens water with copper salts).
Filters/chimneys – remove chlorine (powdered charcoal removes chlorine).
TemperatureHard water tends to have a better silky feel when cooler.
Saltwater has a better silky feel than chlorine water at any temperature.

Soap will smooth and clean skin, but never truly silky. Soap helps the skin absorb moisture more easily, and that is what makes your skin feel soft and smooth.

Minerals are more concentrated at lower temperatures and prevalent in cooler tubs/pools.

Hard water will feel silky at all temperatures. You can refer mineral mix mentioned above as the “silky” effect, but water can be silky when it does not feel silk-like.

How Do I Get The Perfect Water In My Hot Tub?

Balance the pH levelsUse pH up or pH down to adjust your water to the ideal range of 7.2-7.8.
Remove chlorineUse chloramines remover to remove all traces of chlorine from your water and make it feel softer on your skin (for those with sensitive skin)

Add 1oz of bleach per 3 gallons of hot tub water after removing all traces of chlorine, allow the chlorine to evaporate for 12 hours, then drain and refill with fresh water.
Add Alkalinity, hardness, and dissolved solidsAdd 1/3 baking soda per 3 gallons of hot tub water.
Add 1/4 cup Epsom salt per 3 gallons of hot tub water, wait 15 minutes, and then drain and refill with fresh water.
Calcium and MagnesiumAdd 1/3 cup of Epsom salt per 3 gallons of hot tub water, wait 15 minutes, and then drain and refill with fresh water.

Use an Algae Cal (aquatic plant mineral supplement) to maintain a balanced calcium and magnesium composition in the water for maximum softness.
To raise the PH level of your water, use baking sodaAdd 1oz of baking soda per 3 gallons of hot tub water, wait 15 minutes, and then drain and refill with fresh water.
To lower the PH level of your water, use muriatic acidApply 1oz of Muriatic acid per 1,000 gallons to lower the PH level, wait 30 minutes, and then refill with fresh water.
Add ConditionersAdd 1-2 tablespoons of conditioner per 3 gallons of hot tub water.
Add essential oils, fruit, or vegetable essence.Adding essential oils can help soften the water by adding a scent.


Hot tubs and hot water naturally go hand in hand and are second only to the sun. When you shower, bath, or swim in a pool, your body absorbs heat.

The hot water of your hot tub provides the same benefits to its bathers. When adding hard water minerals to your hot tub, you can achieve a silky feeling quicker using salt or baking soda.


Hi! I' am Tom. I was a manager in one of the biggest stores for over 10 Years, am also an SEO by night. I don't like to call myself a blogger; they are very analytical, do email marketing, and know all SEO stuff. I faced many questions from customers about different products, and there was hardly any help on the internet. After learning all the things about these products as a manager the hard way, I decided to start a blog and help other people.

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