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Home > Hot Tub Chemicals > Step by Step Guide

Spa Chemical Guide

This step by step guide is designed to help you get the most out of your spa. By taking the guesswork out of spa maintenance, we aim to help you keep your spa water in peak condition to give you maximum pleasure and enjoyment. Sunspot is Britain’s most comprehensive range of pool and spa products, developed over many years. Within the range are all the products required to create the ideal bathing environment and also safeguard the investment you’ve made in your spa and equipment.

Step by Step Chemical & Spa Care Guide



Step 1: Water Balance

Before water treatment begins, it is important that you read and familiarise yourself with the workings of your spa and support equipment because good water circulation and filtration are essential to achieving a safe and clear bathing environment.

The first step is to ensure good water balance which will create the right conditions for bather comfort, chemical efficiency and equipment protection. The main criteria affecting water balance are calcium hardness, pH and Total Alkalinity.

Calcium hardness

Hardness is the measurement of calcium salts in the water and this will vary depending where you live. Low levels are calcium hardness occur in soft water areas and can lead to corrosion and potential damage to equipment. High levels of calcium hardness occur in areas of hard water and can often lead to the formation of scale in pipework and equipment.

  • Ideal calcium hardness levels for spas is between 100 – 200mg/l.
  • When level is below 100mg/l, apply Sunspot Spa Hardness Plus as per the label directions.
  • When level exceed 200mg/l, apply Sunspot Spa No Scale as per the instructions.


The pH scale has a range of 0 – 14 with 0 being very acidic, 7 being neutral and 14 being very alkali. It is essential to maintain spa water within the 7.2 – 7.6 range which, being slightly alkaline, will protect equipment from corrosion and provide the optimum conditions for bather comfort and sanitiser efficiency.

  • Ideal pH level for spas is between 7.2 – 7.6
  • If the pH is below 7.2 use Sunspot Spa pH Plus as per the label directions.
  • If pH levels exceed 7.6 use Sunspot Spa pH Minus as per label directions.

Total Alkalinity (TA)

Total Alkalinity acts as a buffer to prevent pH change. If TA levels are too low the pH will fluctuate widely and high levels of TA will not only affect water clarity, but also make pH adjustments extremely difficult.

  • Ideal Total Alkalinity for spas is between 125 – 150mg/When TA is below 125mg/l use Sunspot Spa TA Plus as per label directions.
  • When TA is above 150mg/l use Sunspot Spa pH Minus to reduce it as per recommendations made by your Sunspot suppler.

Water balance should be checked regularly and, certainly, every time you top up or refill your spa. 4-way Test Strips are available to help you.

Step 2: Water Treatment

The next step is to keep your spa water in great condition – clean, clear and comfortable.


Spa water must be treated with a sanitiser to kill bacteria which could otherwise thrive in the warm moist conditions. Sunspot offers a choice of sanitiser – bromine or chlorine – and your Sunspot supplier can help you decide which one will be best for you. The sanitiser level should be checked regularly using your test kit or test strips.


Bromine is an effective hot water sanitiser with little odour and therefore ideally suited for use in spas. Sunspot Spa Bromine comes in tablet form making it easy to apply using a fixed brominator chamber which avoids the need for daily dosing.

  • Do not place tablets directly into the spa.
  • The ideal bromine level in a spa is between 3 – 6mg/l.


Sunspot Spa Stabilised Chlorine Granules should be added to the spa on a daily basis as per label directions. These granules have little effect on the pH level and are rapid dissolving, making them easy to apply and a good sanitiser choice.

  • The ideal chlorine level in a spa is between 3 – 5mg/l.


Weekly oxidisation is essential to remove wastes that are too small for  the filter. Sunspot Spa Non Chlorine Shock or Sunspot Spa Granular Shock are the perfect media for oxidising spa water, they will destroy odours and wastes such as perspiration, cosmetics and body oils and restore clarity and sparkle for maximum bather comfort.

Step 3: Spa Speciality Products

The Sunspot Spa range offers speciality products for specific applications and to heighten the pleasure you gain from your spa.

Foam Control

Due to the rapid circulation and aeration of spa water unsightly foam can appear on the water surface, especially when oils and lotions are within the water. Sunspot Spa No Foam should be used regularly to prevent and control excess foaming. When used as per the directions on each pack foaming should rarely become a problem. If excessive foaming is a continuous problem, partially drain the spa and refill with fresh water.

Ensuring water clarity

Discolouration or cloudiness of water is often caused by minute particles suspended in the water, which are too small for the filtration system to remove. Soap, cosmetics, body oils and greases can also cause cloudy, dull water. Spa users should be encouraged to shower before getting into the spa to minimise these problems. A weekly dose of Sunspot Spa Sparkle will assist in the removal of suspended matter via the filtration system thus restoring and maintaining water clarity.


For an extra-sensual spa experience, there’s nothing like enjoying a beautiful fragrance as it wafts from the hot bubbling water.

The Scentsations range of spa fragrances consists of eight scents. The hothouse scents of Gardenia or Tropicana create an exotic atmosphere, the warm scent of peach is reminiscent of the Mediterranean and honeysuckle evokes an English country garden in the summer. Other scents include spring rain, herbal, alpine forest and musk.

The scents are available in 29ml samples or a standard 236ml bottle.

The skin friendly formula of Scentsations is fully compatible with water treatment chemicals and spa equipment.

Step 4: Spa Cleaning

The Sunspot Spa range offers speciality products for specific applications and to heighten the pleasure you gain from your spa.

Surface and water line

Grease and debris can accumulate at the water line, creating an unattractive ‘tide-mark’ and providing an ideal breeding ground for bacteria and algae. Such deposits are easily removed and prevented by using Sunspot Spa Surface Cleaner daily or when the spa is in regular use. The product should also be used to clean all spa surfaces every time the spa is emptied prior to refilling.

Filter Cartridge

When the filter cartridge is dirty, the circulation in the spa may be reduced and the pressure gauge on the filter may show a high pressure. Sunspot Spa Cartridge Cleaner makes cleaning easy and rapidly restores the filtration system to full efficiency. The cartridge should be cleaned at monthly intervals, or more regularly after heavy bather sessions.

Step 5: Maintenance Routines


  • Check sanitiser level and dose as required
  • Check pH level and dose as required
  • Clean water line with Sunspot Spa Surface Cleaner


  • Oxidise spa with Sunspot Spa Non Chlorine Shock or Spa Granular Shock
  • Add Sunspot Spa Sparkle to help obtain beautifully sparkling water
  • Add Sunspot Spa No Foam to control foaming
  • In areas of high calcium hardness add Sunspot Spa No Scale to prevent deposits


  • Clean filter cartridge using Sunspot Spa Cartridge Cleaner
  • Take water sample to your Sunspot supplier to check water balance


  • Due to the build up of Total Dissolved Solids (TDS) the spa will occasionally need to be drained and refilled. There are no hard and fast rules as to when this should be done but the following formula works well in practice.

    • Spa litres ÷ daily bathers ÷ 12 = days between draining and refilling.
    • Example - 1200 litres ÷ 2 ÷ 12 = 50 days.

Spa Safety

  • Never allow water temperature to exceed 40oC
  • Do not drink alcoholic beverages before or during spa use
  • Before children use the spa ensure that the water temperature does not exceed 30oC
  • Do not allow children to use the spa without supervision
  • If you are pregnant, have high blood pressure, any cardiovascular condition or are on medication consult your doctor before using the spa

Chemical Safety

  • Read instructions on each product thoroughly before use
  • NEVER mix different chemicals, including cleaning products, weed-killers and chlorine products as a dangerous reaction may occur
  • When pre-dissolving chemicals always add chemicals to water and never water to chemicals
  • Always pre-dissolve chemicals in a clean plastic container
  • Always handle chemicals in a well ventilated area, preferably outdoors
  • Never use unlabelled chemicals
  • Store chemicals in a cool, dry place
  • Keep chemicals away from children and animals
  • Avoid spillage
  • Always wash hands after handling chemicals

Testing Kits | Sanitisers | Water Balance | Spa Specialities | Shock Treatments | Spa Cleaning | Fragrances | Starter Packs