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How to Shock a Hot Tub

February 1st, 2016 by

cloudy-spa-water-after-shockingWhat does it mean when we speak of shocking a hot tub? I like to say that my spa is shocked every time I remove my towel, but that’s just my little joke. 🙂

Spa shock is an oxidizer that is used to destroy organic contaminants that have been able to escape normal daily sanitation. Oxidation involves the transfer of electrons, and when hot tub water contaminants or pathogens are oxidized, they lose electrons, and quickly expire, or cease to exist.

Today’s blog post is all about shocking a spa or hot tub. What, how, when and why a spa or hot tub is shocked. A shocking topic to be sure!

 

What is Hot tub Shock?

Hot tub shocks are made from a powdered form of oxidizer, either a form of granular chlorine, non-chlorine potassium sulfate salts or liquid chlorine (bleach). When using a biguanide sanitizer system (Aqua Silk), the spa shock is made of liquid hydrogen peroxide, which can not be used in a bromine or chlorine treated spa/hot tub.

Why do I need to shock a hot tub?

There are 3 main reasons to shock a spa: 1. To destroy excessive contaminants in a hot tub after use by several people, 2. To reactivate bromide ions into active bromine, and 3. To kill algae, bacteria, viruses and pathogens that may escape your normal daily sanitation chemical.

How to shock a spa with bromine?

Trick question – you don’t shock a spa with bromine. There is no such thing as bromine shock, although many people confuse bromide ions with spa shock. Bromides (aka Bromine Boosters or Reserve) are used sparingly to boost the ‘bromide bank’, which is reactivated into bromine by using chlorine granules, or MPS (aka non-chlorine shock).

How to shock a spa with chlorine?

Chlorine granules are available in varying concentrations or strengths, so follow label instructions closely for proper dosage. For a 300 gallon spa, 0.7 oz of Chlorine Granules shaken over the water surface, will raise the chlorine level up to about 10 ppm. This should be done with a balanced pH (in the low range of 7.2-7.4), and with the circulation pump running on high to help distribute the shock quickly. Keep the spa cover open or removed for about 30 minutes after adding spa shock, to allow reaction gas to escape and prevent damage to the spa cover. The hot tub should not be used until the chlorine/bromine level drops back below 5 ppm.

How to shock a spa with bleach?

Regular household bleach (non-scented and without additives) can be used in a spa, but the pH level may rise as bleach has a very high pH of 13. For this reason many spa owners may find it easier to use dichlor (chlorine granules) or non-chlorine shock (MPS), which are more pH neutral. Testing the water with a chlorine test kit will determine the proper amount, but for a 300 gallon spa, 1 cup (8 oz) of 5% strength bleach will raise the level to 10 ppm.

How to shock a spa with non-chlorine shock?

Chlorine free shock, also known as MPS (or PPMS) is Potassium Monopersulfate, or Potassium Peroxymonosulfate, is a quick dissolving and powerful oxidizer that is popular for use in spas and hot tubs. It’s not measured with a regular spa test strip, so following dosage instructions is important. For example however, when shocking a 300 gallon spa, 1-2 oz. of non-chlorine shock is used, broadcast over the water surface, with the spa pump running. Like other types of spa shock – add after you use the hot tub, not before.

Is Hot Tub Shock Dangerous?

spa-and-hot-tub-shock-smIt depends if you are shocking with 110V or with 220V! Just another little joke, but seriously folks, Spa Shocks are dangerous – if mixed with any other chemical, or allowed to become moist, or contaminated with dirt or debris, it has the ability to produce noxious fumes, catch fire or explode.

Yes, spa shock can be extremely hazardous, and must be stored in a cool, dry location, safely out of the reach of children. Overdosing your spa or hot tub with shock may damage the finish, or the spa cover. And using the spa before allowing chlorine/bromine levels to subside can bleach swimsuits or cause skin irritation or breathing difficulties.

Always follow the label instructions closely for dosage and use instructions, and keep your spa oxidizers clean, cool and closed. Be safe with spa shock because – oxidants happen! 🙂

 

XOXO;

Gina Galvin
Hot Tub Works

 

 

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