Spa Chemistry

Spa Chemical Maintenance

You cannot operate a spa chemical free!

The importance of proper chemical maintenance of your spa cannot be stressed enough. Proper chemical care is not only critical for user safety and hygiene, but also to prevent damage to equipment due to poor maintenance.

Spas are often overlooked when compared with pools, as far as chemicals are concerned, by pool shop professionals, and owners alike. They are very different from pools in chemical requirements.

Proper chemical maintenance for spas is broken into 3 main categories -

1. Sanitation

2. Oxidation

3. Water Balance

1. Sanitation

Sanitation is achieved in a number of ways, some more effective than others in particular applications. The most popular effective methods are listed below.

Bromine - tablet or granular, Chlorine, Chlorine with Nature 2, Ozone, Biguanide / AQUASPA 

 We do NOT endorse the use of Bromine TABLETS in spas AT ALL due to high incidence of equipment and component failure as a result of incorrect care when using this product. We highly recommend an alternate sanitiser as listed here - the cause - Bromine has a very low acidic pH that constantly drags overall spa pH down. The resultant acid bath, if left uncorrected, causes corrosion of all spa parts. The fact that the tablets are often positioned in the skimmer basket is the main cause of this problem.
Granular bromine does NOT carry the same risks

Ozone - This is definitely our preferred choice of sanitiser in the 24hr CD venturi injection version. A 24hr CIRCULATION PUMP IS ESSENTIAL FOR THIS SYSTEM TO WORK EFFECTIVELY. (otherwise we highly recommend you consider the AQUASPA chemical system discussed below). An extremely effective sanitiser when set up correctly. Don't assume all ozone systems work effectively - most spas are not set up with 24 hour ozonation. In these cases ozone must be complimented with significant doses  of one of the other sanitiser systems listed above. Generally these systems only operate when the main pump is running 2-6 hours per day. Ozone only lasts for 18 seconds after the generator stops producing, therefore the other 18-22 hours per day need another form of sanitiser. These systems do cut down on chemical requirements, proportional to the time run per day. A corona discharge system fitted and set up to operate 6 hours minimum will effectively kill bacteria in the spa already, meaning that a residual sanitiser level of another type may be all that is required.

True 24 hour Ozone - Extremely effective sanitiser for spas. When ozone is generated 24 hours per day at the correct levels, it offers around the clock operation. The amount of additional sanitiser required is minimal. This can depend on a number of factors such as showering before use, number of users, and ozone levels produced. The addition of a non-chlorine oxidiser after each use will destroy user introduced organic waste, etc. The most effective form of 24 hour is that where the system incorporates the use of a circulation pump and a venturi ozone injector. These systems are generally found on American spas, but are becoming more widespread with a number of Australian Spa Manufacturers adopting this style of sanitation.

Two types of ozone generation exist - Ultra-violet and Corona Discharge.

UV generators are cheaper to purchase, but require frequent lamp replacement (every 3 years) to ensure effective output. Corona Discharge Ozone generators produce a constant output for their life at a higher rate than UV generators, so are more effective, but at additional cost. They are usually unrepairable, and require replacement. CD generators are the better choice.

Click Here for data on Ozone's effectiveness as a sanitiser

Nature 2 / Spa Frog - This system utilizes a cartridge containing silver particles to react with bio-organisms with effective killing power. It is completely odour free, has no impact on pH, and requires no ongoing adjustments. It is simply replaced every 3-4 months when the spa is drained and refilled. When used in conjunction with chlorine (lithium Hypochlorite) correctly, this method is a good choice for minimising chemicals. Not to be used with Bromine.

Chlorine - Lithium Hypochlorite only - a common cost effective sanitiser - it alters the pH - upwards - requiring acid to lower pH. It is also necessary to add chlorine 2-3 times per week when used as a sanitiser. It is an excellent additive in conjunction with the use of ozone or Nature 2.
You must NOT use swimming pool liquid, granular or tablet chlorine in spas. Lithium Hypochlorite is formulated for spas. Unfortunately Lithium supplies are drying up so this product will only likely be readily available until late 2017/18.
Granular Bromine - used in the same manner as Lithium Hypochlorite, but it has a pH of approx 4.5 so requires pH up adjustments. It will become more widespread when lithium supplies dry up. It is an excellent sanitiser.

2. Ozidation

This is the process of burning out organic waste, body oils and fats, and breaking down the oxide barrier on chemicals and chemical by-products. This is a critical component of effective spa care and must be used with all sanitiser systems. Commonly used oxidisers are Chlorine, Potassium Monopersulphate, and Sodium Carbonate Peroxyhydrate.

3. Water Balance

Chemical water balance is often overlooked in spas, often as a result of mis-information. Proper water balance is critical to ensure a near neutral, slightly alkaline pH. This ensures spa user safety, extends the life of equipment, particularly heaters, and importantly, is necessary to maintain manufacturers warranty. There are a number of chemicals necessary to ensure a stable accurate pH.

1. pH Buffer - Total Alkalinity Increaser - Bi-Carb - this product stabilises pH and prevents 'pH Bounce' when kept at correct level.

2. pH Increaser - Soda Ash - used to raise pH when low.

3. pH Decreaser - Dry Acid - used to lower pH when high.

Proper Levels

Total Alkalinity   80-120 ppm

pH                    7.2 to 7.8 (ideally 7.4-7.6)

Bromine            3 to 5 ppm

Chlorine            1 to 3 ppm

Ozone                0.01 ppm

Calcium Hardness 150 to 400 ppm

To check these levels, it is necessary to test with the relevant test strips or kit. Testing frequency depends on use, water temp, and sanitiser system. Generally you should test at least weekly.

When adjusting - Total Alkalinity should be adjusted first, then pH, and sanitiser.

Other Chemical Products

Foam Retardant - a product that reduces surface foaming whilst using the spa - generally foaming is due to improper chemical care, detergents from clothing, body oils, etc. It's usually time to drain and refill when foaming occurs, rather than 'masking' the problem with this product. Don't use if not absolutely necessary.

Clarifier - clears cloudy water - it clumps minute particles to allow them to be trapped in the filter. As a side effect, it will reduce filter life due to clogging.
Not recommended for use with Sundance Spas equipped with Microclean filters, Arctic Spas fitted with optional micro cartridges, LA Spas fitted with Bag Style filters, and any other similar designs - these filters provide super fine filtration, but will clog rapidly with clarifier, thus shortening filter life for Sundance Spas, artesian Spas and Arctic Spas, and increasing cleaning frequency for LA Spas and Southwest Spas filters. Only use a clarifier if you can't achieve clear water after 48 hours of refilling, and frequent filter cartridge washing. Don't use if not absolutely necessary.  Only use a clarifier with standard pleated filter cartridges.

Spa Bath Cleaner / Pipe Cleaner - frees built up grime inside spa bath pipework. This should be carried out twice annually. It should also be used on outdoor spas at least bi-annually.

Products we recommend avoiding - 'pool chemicals', Tablet Bromine, lLiquid chlorine, liquid acid, 'multi action' chemicals (these chemicals adjust a number of levels simultaneously. This is not desirable when only one or 2 adjustments may be required. It results in over or under dosing, worse water condition and spa jet/heater damage). 
Despite being sold as a 'spa' chemical, Perfect Balance or other single dose pH stabilising products are NOT recommended as they impractically (and in many cases impossibly) require heaters to be off for 24-48 hours after introduction. If a heater is left on, calcium can deposit causing element failure. Small circulation pumps can suffer the same fate due to their high running temperature.
Avoid use of ANY product designed to be introduced by, or positioned in the pool or spa skimmer - use of such chemical addition will cause premature failure of heaters and other equipment.

Calcium Hardness Increaser - used to increase calcium hardness levels in your spa. Generally not required unless rain water is used to fill your spa, but is very important that it's at the correct level.


Always refer to the manual for your spa for specific chemical instructions that may be applicable to your spa.  Warranty may be void if manufacturers instructions are not followed.

Adding chemicals directly in the skimmer (or in close proximity) results in a higher concentration flow through the equipment, particularly the heater which will corrode or scale excessively and prematurely fail
It may well be a convenient way to add chemicals, but its a sure fire way of emptying your wallet as well !