Dichlor Vs Trichlor vs Cal hypo vs Sodium Hypo – PRO’s & CON’s

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The difference between dichlor vs trichlor is that Dichlor (or dicholoro-s-triazinetrione) is available in anhydrous or dihydrate form while Trichlor (or trichloro-s-triazinetrione) is a solid compound having the highest cholorine content (about 90%).

  • Dichlor Chlorine content in Dihydrate form is 56% while
  • Dichlor Chlorine content in Anhydrous form is 62%.

They both can clean spa water, hot tubs and swimming pools.

PS: Dichlor for shocking is generally a no-no because it increases the Cyanuric Acid level.

What is the Difference Between Trichlor and Dichlor?



Cal Hypo (Granular or tablets)

Lithium Hypochlorite

Name Trichlor is the short name of trichloro-s-triazinetrione Dichlor is the short name of dichloro-s-triazinetrione. Cal Hypo Lithium hypochlorite
Physical State Available in dry form Granular form Tablets or Granular Powder
Types No types Two different types as dihydrate and anhydrous form No types No types.
Chlorine Content Around 90% 56% (dihydrate form).

62% (Anhydrous form).

65% and 75% 23-35%
Function It eradicates pathogenic organisms in the water Get rids of algae and pathogenic organisms in the water. Clarify the water

It reduces water stain and scale formation

It is an algicide, disinfectant, fungicide and food

contact surface sanitizer


 Dichlor Vs Trichlor for Pool or SPA

Trichlor has more chlorine by weight and less CYA by weight than “PURE” (anhydrous) Dichlor. However, the chlorine contained in the Trichlor has more weight (per molecule) so the net effect is that in 10,000 gallons 1 pound of Trichlor equals 11.0 ppm FC and 6.7 ppm CYA while a single pound of Dichlor equals 6.6 ppm FC and 6.0 ppm CYA.

Note: This result only applies to Dichlor that is DIHYDRATE.

Part of the reason dichlor sucks is that you are buying water with it – Did you know? I guess not.

By buying the “dry form”, you are buying hydrated crystal with the Dichlor.

ANHYDROUS Dichlor on the other hand 1 pound equals 7.7 ppm FC and 7.0 ppm CYA. So, with anhydrous, you enjoy a bit more CYA per pound than you would with Trichlor. However, anhydrous Dichlor isn’t as readily available as its counterpart so you’d most likely be seeing dihydrate form more.

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Dichlor Vs Trichlor vs Cal hypo vs Sodium Hypo

Trichlor Vs Dichlor Vs Cal Hypo

Dichlor increases your water CYA levels at an even quicker rate than Trichlor so I would discourage using it unless your aim is to increase the CYA levels.

Also, when calculating the actual amount of chlorine (FC) you get, Trichlor costs less than Dichlor, even accounting for the pH Up you need Trichlor.

As earlier stated, you cannot compare products based on weight only since they contain different levels of chlorine.

In most cases, chlorinating liquid or bleach are the cheapest way to go. Cal-Hypo is close (at times cheaper, depending on where you buy from), then Trichlor, then Dichlor and lastly Lithium Hypochlorite which is very expensive.

Remember the following chemical rules of fact that are independent of concentration or size of pool:

  • For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
  • For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.
  • For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
  • For every 10 ppm FC added by Sodium Hypo, it also increases Salt levels by 17 ppm.

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Sodium hypo vs. Cal hypo vs. Trichlor

  • Sodium Hypo (liquid chlorine)

This is a widely used option where available. But, its super high pH (13) OF LIQUID CHLORINE, a gallon of acid is typically needed for every 10 gallons of bleach you use.

Keep in mind that maintaining a consistent alkalinity and pH can become increasingly difficult.

Liquid chlorine systems also need a safe space for large chlorine vats, and close access for a bleach delivery truck.

  • Cal Hypo (granular or tablets)

This is yet another favorite for pool owners whose pool require high chlorine demand. Granular pH level is 11 (this is fair if you ask me) but its tablets levels are lower than 9.

It will either contribute to salt levels (sodium) or cyanuric acid, but it does boost calcium hardness levels in the pool, which is a bad thing for hard water areas.

In most cases, the tablet form come pre-mixed with additives to help clarify the water or reduce scale and stain formation.

  • Trichlor (3″ tablets or sticks)

These are rarely used by large commercial pool owners because they don’t just dissolve quick enough to meet the chlorine demand, but are more suitable to pools under 50,000 gallons.

Being stabilized, Trichlor tablets may build up CYA (cyanuric acid) in pools over time, needing more periodic additions of fresh water.

Featuring a very low pH level means Trichlor tablets depress the pool water pH and alkalinity levels, requiring frequent additions of pH increaser.

Is Dichlor the Same as Shock?

Dichloroisocyanuric Acid is a type of chlorine shock. Dichlor has both cyanuric acid and chlorine and will, over time, raise your CYA levels.

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What is Dichlor used for in Pools?

Dichlor is generally available in granular, providing owners an easy yet efficient way to chlorinate spas and pools.

It can also be used for extra water treatment functions such as controlling algae and oxidize contaminants and chloramines.

Does Trichlor raise CYA?

Yeah, it does but not as much as Dichlor. For every 1 pound of trichlor added (roughly two 3” tablets) to 10,000 gallons of water, the CYA increases 7 ppm.

Can You Use Calcium Hypochlorite and Trichloro S Triazinetrione?

Never mix them. If you do, they’ll react as they dissolve and you won’t like the result. Trichlor contains acid and calcium hypochlorite contain alkaline. These two just don’t belong together.

Will Dichlor kill algae?

Yeah. It will attack algae and organic matter buildup.

Does Dichlor raise pH?

Yeah, it will but you’ll hardly notice it.

Can you shock with Dichlor?

Dichlor for shocking is generally a no-no because it increases the Cyanuric Acid level.

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Author: Howard S. Baldwin

My name is Howard S. Baldwin. I am a work-at-home dad to three lovely girls, Jane + Hannah + Beauty. I have been blogging for the last 3 years. I worked for other Home and Lifetsyle blogs, did hundreds of product reviews and buyers’ guides. Prior to that, I was a staff accountant at a big accounting firm. Needless to say, researching and numbers are my passion. My goal is to be an informative source for any topic that relates to DIY life and homemaking.

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