Pool Shock: Best Shock for your Pool Type

Dr. Pool of In The Swim

You may be wondering why we have developed so many types of granulated oxidizers, known more commonly as pool shock.

The answer is quite simple; there are various pool types and different uses for pool oxidizers, and our different formulations meet these needs accordingly.

What’s the best shock for your pool? Let’s explore the possibilities…

Vinyl Pools

Vinyl is a type of plastic made by joining ethylene and chlorine, to create polyvinyl chloride, commonly known as PVC. It is then extruded into long rolls of a thin and flexible material used to line inground and above ground swimming pools.

Even though it’s made with chlorine, keeping your water over-chlorinated for long periods of time can draw the resins from the vinyl, causing it to lose it’s plasticity. Bleaching of vinyl liners is also a problem, when granular chlorine added to the pool sinks to the bottom before dissolving.

For a vinyl pool, we have 3 types of oxidizer that can be used safely, and without having to pre-dissolve in a bucket before adding to the pool.

chlorine-free-pool-shockNon-Chlorine Shock – This oxidizer is 100% potassium peroxymonosulfate; a mixture of salts, which is completely safe to handle and store. You can pour it right in the pool and swim immediately. Full sanitation in a quarter of the time of chlorine.


hth-shock-and-swim-pool-shockShock and Swim – As the name implies, this form of calcium hypochlorite has been formulated with high pressure compaction and granulation techniques to produce an extremely small particle size. Instantly dissolving, you can swim within minutes.


lithium-pool-shockLithium Pool Shock – The cleanest burning, fastest acting pool shock is also a very rare heavy metal. Lithium shock won’t bleach vinyl liners, and won’t contribute to calcium hardness levels. Unlike cheaper pool shock, Lithium won’t leave behind messy residue in your pool.


Fiberglass Pools

A fiberglass pool is a molded shell of fiberglass, coated with a gelcoat, similar to a boat or pool slide. It has a durable surface that is less affected by chlorine than a vinyl pool, but more than a gunite pool.

To care for your gelcoat and reduce staining and fading of a fiberglass pool, pre-dissolve pool shock into a bucket filled with water.

You can use the pool shocks listed above for vinyl pools, or try these two oxidizers, strong but gentle pool shocks.

best-pool-shock-liquid-pool-shockInstant Liquid Chlorine – A highly granulated form of calcium hypochlorite, our Instant Liquid Pool shock needs no pre-dissolving, and is much safer to store and handle than sodium hypo, or liquid chlorine. Pours easily from a specially designed bottle.


Super Shock and Swimhth-super-shock-and-swim-pool-shock – The big brother of regular Shock and Swim, also known as Sock-It ®, made by Arch Chemicals. Fast dissolving formula is pH balanced and leaves nearly no residue after oxidation is complete.


Concrete Pools

A concrete pool has a shell of gunite or shotcrete, covered with a waterproof layer of plaster, sometimes mixed with quartz, pebble or bead aggregates for added strength, color and texture.

Depending on the composition, you can use fairly aggressive oxidizers in a concrete pool. Plain plaster pools without large aggregate may develop pitting and etching from pool shock, especially during the first year of the pool surface.

For a concrete pool, you can use any of the pool shock listed above, or you can use some of our less expensive to produce oxidizers, such as these below.

cheap-pool-shockPool Shock – our lowest priced pool shock, this multipurpose form of calcium hypochlorite has 65% available chlorine, one of our strongest forms of pool shock. Dilute this shock in a bucket for best dispersion and apply after the sun has gone down.


dichlor-pool-shockAssure Multi-Shock – Sodium Dichlor is a favourite pool shock, this oxidizer has added clarifiers and stabilizers to help reduce the oxidation demand and protect the active molecule from the sun. Coagulates smaller particle into larger clumps.


cheapest-pool-shockCal-Chlor Sanitizing Granules – Our most powerful pool shock, 68% available chlorine. Commercial pool operators love this product, and it’s packaged in buckets of 25 or 50 lbs. for easy and quick application for algae or fecal incidents.


He's from the TV show Big Bang Theory.

I could talk about oxidizers all day long ~ but, I’ve other work to do here at the lab. Here’s a little chemistry humor to lighten your day. If you have other questions about which pool shock to use, or want me to explain this joke, call us, or send me an email!






Dr. Pool






Pool Shock: Best Shock for your Pool Type — 4 Comments

  1. Hi!
    My daughter has bad skin reaction for chlorine. I saw some recommendations to use liquid Baquacill or Phosfree here: https://greenyardmaster.com/best-pool-shock/
    I want to try one of these products next season. Would it be good for my kid? Do you have any experience of using Phosfree or Baquacill? Or maybe, is it better to choose InTheSwim Non-Chlorine Shock?

    • Hi Brian, Baquacil or other Biguanide products like Soft Swim, Revacil or Aqua Silk, are the only standalone sanitizer option to chlorine. I have some experience with pools that were treated with it – personally I don’t like it because of the side effects – gummy goo that clogs filters, or pink slime problems or endless cloudy water issues. However, thousands of people use the product and are very happy with the results, with few ‘side effects’. Phosfree is not a sanitizer, only a phosphate remover. Another option to Biguanides is to use Ozone, UV systems or Mineral Systems. Using Minerals + UV, or Minerals + Ozone, coupled with a weekly non-chlorine shock, and algaecide treatment – and you can be chlorine free – although I would still shock monthly with chlorine, just to be sure all the bacteria is dead.

    • Hi Zach, yes – safe IF you pre-dissolve it first, by pouring it into a 5 gal bucket, filled with water, and stirring to dissolve. Pour in most of it, but some grains will remain on the bottom. Refill the bucket, and stir for another minutes, to dissolve, then add the remaining, or let it sit in the bucket and add the rest an hour later.

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