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Hot Tub Chemical Maintenance

Owning a hot tub doesn't require a lot of hard work. A few simple routines will keep your water sparkling clean and your hot tub in excellent condition. This guide has been written with the view of making you hot tub water safe, you may find some guides online that are less stringent. However, we recommend that this guide is followed as to make sure all risks involved with water care will be reduced to a minimum, so that you and your family can enjoy your hot tub in safety.

In essence this is a Hot Tub care guide for Dummies, & if you need them here are our Hot Tub Starter Pack for Dummies

  1. Close all drains and fill the hot tub with water by putting the hose down the center of the gray standpipe in the filter compartment. This will minimize airlocks in the equipment by filling through the heater, pumps and jets, pushing most of the air out of the lines . The water level of your hot tub should be maintained at a level of 1½ inches above the highest jet.
  2. After the spa has been filled with water and the equipment compartment door is secured, power must be applied to the spa.
  3. The jet pump(s), heating system and all internal plumbing will achieve a partial prime as the spa is filled. Once the jet system is fully operational (as indicated by strong, non-surging jets), priming of the spa is complete. Weak or surging jets are an indication of a low water level condition or clogged filter cartridges or air lock.
  4. Adjust Total Alkalinity (TA) to 80 ppm, then spa water pH to between 7.2 and 7.6. IMPORTANT: Add spa water chemicals directly into the filter compartment with the jet pump on high speed for at least ten minutes. NOTE: Adjusting the Total Alkalinity as the first step is important, as out-of balance TA will affect your ability to adjust the pH correctly and will prevent the sanitiser from operating effectively.
  5. Superchlorinate the spa water by adding 20 grams of chlorine per 1000 litres of spa water. The jet pump should be running on high speed when adding the chlorine, and remain on high to circulate the spa water for a ten-minute period.
  6. Set the temperature control to the desired temperature (typically between 37 & 40 degrees centigrade), then place the thermal cover on the spa and allow the water temperature to stabilize (approximately 10 - 12 hours). Make sure you secure the cover in place using the cover locks. Periodically check the spa water temperature. When the water temperature climbs above about 32 degrees centigrade, proceed to the next step.
  7. Recheck the Total Alkalinity (TA) at 80 ppm, then spa water pH at between 7.2 and 7.6.
  8. OPERATION NOTE: Make sure you adjust your Total Alkalinity first, as an out-of-balance condition will affect your ability to adjust the pH correctly, and will prevent the sanitiser from operating effectively. The spa is ready for use when the spa water has circulated and the chlorine level remains between 3 ppm and 5 ppm.

  • Using Test Strips check sanitiser level & dose as required.
This table may be scrollable
SanitiserRecommended levels for a spa
Chlorine3 - 5 ppm
Bromine4 - 6 ppm
Active Oxygen5 - 10 ppm (When spa is in use)

  • Oxidise hot tub with a Non-Chlorine Shock. according to dose rates on packaging.
  • If you have topped up your spa with fresh water and you are in an area of high calcium hardness add an Anti Scale. to prevent scale deposits
  • Your filter should be removed and sprayed with a garden hose to remove debris, hair, leaves etc.

We recommend that you clean your spa's filter about once every 6 weeks with a Hot Tub Filter Cleaners solution . Filter cleaning is important because dirt and debris trapped in your spa's filter can slow the flow of water and affect the performance of the spa. The process is simple: place the filter into a bucket with filter cleaning solution and allow the dirt and particles to float into the water. After soaking, the filter should be sprayed thoroughly again to remove any remaining dirt and cleaner fluid.
You may want to buy an additional filter to keep on hand. This way, you can allow your filter to soak, put the replacement filter in and use your hot tub right away.

It's a good rule of thumb to drain and clean your spa about once every three to four months. If you have an acrylic shell, it's simple to clean, and you can be assured that the non-porous surface won't allow dirt, soapy film, or germs to penetrate. Simply use a Surface Cleaner. , and wipe the acrylic with a damp sponge or cloth. Never use an abrasive cleaner or a product that contains bleach.

Due to the build up of Total Dissolved Solids (TDS) the hot tub will need completely draining & refilling. There are no hard and fast rules as to when this should be done but the following formulation seems to work well in practise:
Hot tub litres divided by daily bathers divided by 12 = days between draining & refilling
Example : 1200 litres divided by 2 bathers divided by 12 = 50 days.

Water Balance Terminology

By balancing the water you are creating the right conditions for bather comfort, chemical efficiency & equipment protection. A number of factors are involved in balancing the water but the main areas are : Calcium Hardness, Total Alkalinity & pH

Calcium Hardness
This will vary depending on where you live and where your water supply comes from and it is very important that the correct level is established. As a guide soft water tends to be low in Calcium Hardness and hard water more obviously is high. The level should be checked each time you top-up or refill the hot tub with fresh water. The ideal Calcium Hardness level for hot tubs is between 100 - 200mg/l.

When it is below this level the water could be corrosive which could lead to damage of plant equipment such as the heater. If this is the case apply Hardness Increaser to achieve the correct level.
When it is above this level the water has a tendency to appear cloudy and also calcium can precipitate out and deposit itself on the tub shell finish, heater element, cartridge element & within pipework. If this is the case apply No Scale to achieve the correct level.

Total Alkalinity
TA acts as a buffer to prevent pH change and if the level is too low the pH will fluctuate widely, if too high pH adjustment will be difficult to effect. The ideal Total Alkalinity for hottubs is between 125 - 150mg/l. When it is below this level not only will pH fluctuate but the water could be corrosive, cause damage to equipment and be uncomfortable to bathers. Use Total Alkalinity Increaser to raise levels.
When it is above this level not only is pH difficult to adjust but also the water could be scale forming and clarity impaired. Use pH Minus to reduce levels.

pH Levels
Regular pH checks are an essential part of your tub maintenance routine using Test Strips.
The pH scale has a range of 0 - 14 with 0 being very acidic, 7 being neutral & 14 being very alkali. For tubs the ideal range is between 7.4 - 7.6, this being slightly alkaline to protect the hot tub and prevent equipment corrosion. This also provides the most comfortable conditions for bathers and good sanitiser efficiency.
If the level is below 7.4 use Soda Ash to raise the level.
If the level is above 7.6 use Dry Acid to reduce the level.

The sanitising of your hot tub water is necessary to kill bacteria and help in the prevention of algae growth. The level should be checked regularly using Test Strips and can be in the form of Chlorine or Bromine

This is an effective hot water sanitiser and ideally suited to hot tubs.
It is effective over a wide pH range and has little odour.
Comes in tablet form making it easy to apply and avoids having to dose everyday.
The ideal Bromine level is between 3 - 6mg/l.

This is available in granule form which are rapid dissolving and therefore a good sanitiser.
It has little effect on the pH levels.
The ideal Chlorine level is between 3 - 5mg/l.

It is necessary to oxidise your hot tub weekly using Non Chlorine Shock.
It destroys odours and wastes such as perspiration, cosmetics and body oils.
Restores sparkle.
Increases bather comfort.

Hot Tub Speciality Products.

Other products also help keep your hot tub clean, clear and enhance your bathing pleasure.
Control of Foam
The rapid circulation & aeration of hot tub water can cause unsightly foam to appear on the waters surface especially when oils and lotions are within the water.
No Foam used regularly will prevent and control excess foaming.
If excessive foaming is a continuous problem drain the tub and refill with fresh water.

Ensuring Water Clarity.
Discolouration or cloudiness of the water is often caused by minute particles suspended in the hot tub water which are too small for the filtration system to remove.
Soaps, cosmetics, body oils and greases can all cause dull, cloudy water.
Encourage hot tub users to shower before getting into the hot tub to minimise these problems.
Clarifier used once a week will assist in the removal of suspended matter via the filtration system thus restoring and maintaining the water clarity.

Bubbletubs Ltd
Unit 2 New Barns Farm
WV15 5PB

VAT: 834 2050 60
Registered: 4995297