Di-Chlor vs Cal-Hypo

In this video, we talk about the difference between Di-Chlor and Cal-Hypo (both of which can be used to shock your pool). Di-Chlor vs Cal-Hypo covers the side-effects of each so you can determine which option is ideal for you!

Here is brief overview of what is covered in the video:




  • Technical name is Sodium Dichloro-S-Triazinetrione
  • Di-Chlor has 55% free and available chlorine to fight algae in your pool
  • The Di-Chlor Shock we sell is 99% Sodium Dichlor, which means 54.8% free chlorine
  • Di-Chlor also contains Cyanuric Acid (CYA) which acts like sunscreen for your chlorine
  • If your CYA is already high, then Di-Chlor is probably not the best option for you
  • For ever 1ppm of FC added, Di-Chlor will increase CYA by 0.9ppm

Shop Di-Chlor HERE




  • Technical name is Calcium Hypochlorite
  • Cal-Hypo has 99.18% free and available chlorine to fight algae in your pool
  • The Cal-Hypo Shock we sell is 68% Calcium Hypochlorite, which means 67.4% free chlorine
  • Cal-Hypo contains calcium, which will increase the calcium hardness (CH) level in your pool
  • For every 1ppm of FC added, Cal-Hypo will increase CH by 0.7ppm

Shop Cal-Hypo HERE


We also carry 73% Cal-Hypo

Should You Use Di-Chlor or Cal-Hypo?

First, you should test your water. We recommend the TF-100 test kit by TFTestkits

After you test your water, take a look at your CYA and CH levels, and compare them to recommended levels (below).

Recommended CYA Levels:

Pools with a Salt Water Generator (SWG) : 60 – 80 ppm
Pools without a Salt Water Generator : 30 – 50 ppm

Note: If you let your CYA get too high, your chlorine will lose effectiveness to fight algae. If your CYA is too low, then your chlorine will burn off from the sun very quickly.

Recommended CH Levels:

Vinyl Pools : 0 – 350 ppm (You don’t need any CH, but up to 350 wont hurt anything)
Plaster Pools : 250 – 350 ppm

Note: If your CH level is too high, you run the risk of getting calcium scaling.

Based on your test results, and the recommended levels, choose the best option for your pool. If your CYA is low and your CH is high, then you should use Di-Chlor. If your CYA is high and your CH is low, then you should use Cal-Hypo.

If your CYA and CH levels are both high, you have another options. Liquid Chlorine will add free chlorine (FC) to your swimming pool without increasing your CYA or CH levels. You can use bleach from a local store if you prefer, but remember to check the strength!

Here is a picture of the whiteboard:

Di-Chlor vs Cal-Hypo

If you have any questions, feel free to contact us here.

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When Kevin’s not enjoying the water himself he’s engaging himself in the wide world of pool and spa knowledge which he passes on to our customers through producing content for our blogs and website. Outside of the pool world you can find him enjoying life with friends, family and his off the wall dog Brixton.