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Green Water & Algae

Liquid Chlorine vs Granular Shock

Both raise free chlorine. What separates them is what else they leave behind, and that decides which one your pool can take repeatedly.

By Scooter M.Last reviewed September 2, 2026How we work the numbers out
Pool chemicals measured out at the poolside before dosing

We have not handled these products and we do not pretend to have. Here is what we did instead. Links to Amazon earn us a commission at no extra cost to you, and commission never decides a pick — disclosure.

Liquid Chlorine vs Granular Shock - ranked
#ProductBest forThe spec it turns onPrice
1
Champion Pool Shock Liquid Chlorine 12.5%, 1 gal, 4-pack
Champion Pool Shock Liquid Chlorine 12.5%, 1 gal, 4-packTop pickAdds nothing but chlorine and salt, which on a big bloom or a saltwater pool is exactly the point.
Large blooms and saltwater pools12.5% trade sodium hypochlorite, ready to use, no residue
Check price#ad
2
In The Swim Pool Shock, 68% Cal-Hypo Granular, 25 lb
In The Swim Pool Shock, 68% Cal-Hypo Granular, 25 lbThe highest available-chlorine percentage in common retail cal-hypo, sold loose so you dose by weight instead of by packet.
Clearing an algae bloom68% available chlorine, calcium hypochlorite, sold loose by the pound
Check price#ad
3
In The Swim Sodium Dichlor Chlorine Shock Granules, 25 lb
In The Swim Sodium Dichlor Chlorine Shock Granules, 25 lbThe liner-safe shock in a format you can actually weigh, if you are prepared to watch cyanuric acid climb.
Vinyl liners and fiberglassSodium dichloroisocyanurate, fast dissolving, sold loose
Check price#ad

The decision in one table

Liquid chlorine against the two common granular shocks
Liquid chlorineCal-hypo granularDichlor granular
Typical strength10-12.5% trade47-73% available chlorine56% available chlorine
AddsSalt onlyCalcium hardnessCyanuric acid
pH effectRaisesRaisesRoughly neutral
DissolvesInstantlyNeeds pre-dissolving on vinylFast, broadcast-safe
Storage lifeWeeks in heatA season if kept dryThe best of the three
HandlingHeavy, splashes, bleaches clothingDusty, reacts with organicsDusty
Best forHard water, saltwater, big volumesBlooms, stabilized poolsVinyl liners

The cost comparison people get wrong

Comparing a gallon of liquid to a pound of granular tells you nothing. The only fair comparison is cost per ppm in your pool, and that means converting both to the same unit first.

The dose tables, side by side

12.5% liquid chlorine for a 10 ppm shock
Pool volumeHow much
5,000 gal51 fl oz
10,000 gal102 fl oz
15,000 gal1.2 gal
20,000 gal1.6 gal
25,000 gal2 gal
30,000 gal2.4 gal
Where these come from: gallons of liquid chlorine = (ppm x pool gallons) / (trade % x 10,000). For 15,000 gallons that is (10 x 15,000) / (12.5 x 10,000) = 1.2 gal. How we work these out.
68% cal-hypo for the same 10 ppm shock
Pool volumeHow much
5,000 gal10 oz
10,000 gal1.2 lb
15,000 gal1.8 lb
20,000 gal2.5 lb
25,000 gal3.1 lb
30,000 gal3.7 lb
Where these come from: lb = (ppm x gallons x 8.345) / (1,000,000 x available-chlorine fraction). For 15,000 gallons that is (10 x 15,000 x 8.345) / (1,000,000 x 0.68) = 1.84 lb. How we work these out.

Pick liquid chlorine if

  • Your calcium hardness is already above roughly 400 ppm, or your fill water is hard
  • You have a saltwater pool - liquid chlorine is chemically what the generator already makes
  • Your cyanuric acid is high and you cannot afford to add more
  • Your pool is large enough that carrying granular in the quantities needed is genuinely annoying
  • You will use it within a few weeks and can store it somewhere cool

Pick granular cal-hypo if

  • You want it on the shelf for whenever the pool needs it, rather than buying fresh
  • Your calcium hardness is low and could use the addition
  • You are carrying it any distance - 25 lb of cal-hypo holds far more chlorine than 25 lb of liquid
  • You are shocking a bloom and want maximum chlorine per unit of effort

Pick dichlor if

  • You have a vinyl liner and do not want to pre-dissolve every dose
  • Your cyanuric acid is genuinely low and needs raising anyway
  • You want the most storage-stable option of the three

The picks

Champion Pool Shock Liquid Chlorine 12.5%, 1 gal, 4-pack

Top pick - Large blooms and saltwater pools

Champion Pool Shock Liquid Chlorine 12.5%, 1 gal, 4-pack

Adds nothing but chlorine and salt, which on a big bloom or a saltwater pool is exactly the point.

The published figure

12.5% trade sodium hypochlorite, ready to use, no residue

12.5% trade means one gallon raises 10,000 gallons by 12.5 ppm. That identity makes it the easiest chemistry on this page to dose in your head, and it stops being easy the moment your pool is not 10,000 gallons — see the calculator below.

Liquid chlorine adds no calcium and no cyanuric acid. For a pool that is already hard, already stabilized, or salt-chlorinated, that is the whole argument.

It also degrades. Sodium hypochlorite loses strength in storage, faster when warm, so a jug that has sat in a hot garage since last summer is not 12.5% any more.

What it does well

  • Adds no calcium and no cyanuric acid
  • Dissolves instantly, no pre-mixing, no granules on the liner
  • Cheapest route to a large ppm swing on a big pool

What it costs you

  • Loses strength in storage, particularly in heat
  • Heavy and awkward to handle at four gallons
  • Raises pH, so expect to follow with acid

Skip it if you cannot store it cool and use it within a couple of months — you will be dosing an unknown percentage.

Check price on Amazon

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In The Swim Pool Shock, 68% Cal-Hypo Granular, 25 lb

Pick 2 - Clearing an algae bloom

In The Swim Pool Shock, 68% Cal-Hypo Granular, 25 lb

The highest available-chlorine percentage in common retail cal-hypo, sold loose so you dose by weight instead of by packet.

The published figure

68% available chlorine, calcium hypochlorite, sold loose by the pound

68% available chlorine means 1 lb raises 10,000 gallons by about 8 ppm. A green pool typically needs 10 to 30 ppm depending on how far the bloom has gone, which is 1.2 to 3.7 lb per 10,000 gallons.

Loose granular is the format that lets you weigh a dose. Pre-measured 1 lb packets are convenient and fine for weekly maintenance, but they force you to round a shock dose to the nearest pound, which on a small pool is a 30% error.

Cal-hypo adds calcium hardness and no cyanuric acid. That is the right trade for a bloom and the wrong one for a pool that already sits above 400 ppm calcium.

What it does well

  • 68% is the top of the common retail range, so you carry and store less product per ppm
  • Loose granular lets you weigh an exact dose rather than round to a packet
  • Adds no cyanuric acid, so shocking repeatedly does not drive you into chlorine lock

What it costs you

  • Adds calcium hardness with every dose
  • Must be pre-dissolved in a bucket for vinyl liners, which the label states
  • A 25 lb bucket is more than a small pool will use in a season

Skip it if your fill water is already hard, or you own a small above-ground pool that will never work through 25 lb before the bucket cakes.

Check price on Amazon

#ad · how this is funded

In The Swim Sodium Dichlor Chlorine Shock Granules, 25 lb

Pick 3 - Vinyl liners and fiberglass

In The Swim Sodium Dichlor Chlorine Shock Granules, 25 lb

The liner-safe shock in a format you can actually weigh, if you are prepared to watch cyanuric acid climb.

The published figure

Sodium dichloroisocyanurate, fast dissolving, sold loose

Dichlor dissolves fast enough to broadcast directly, which is the practical argument for it on a vinyl liner where undissolved cal-hypo granules bleach the pattern.

Buying it loose rather than in packets is the same argument as the cal-hypo above: an exact dose beats a rounded one.

Keep a cyanuric acid test to hand if this is your regular shock. The stabilizer it adds is the reason it needs watching.

What it does well

  • Safe to broadcast on vinyl and fiberglass without pre-dissolving
  • Loose format allows a weighed dose
  • pH neutral

What it costs you

  • Adds cyanuric acid on every dose
  • 56% available chlorine means more product per ppm than cal-hypo

Skip it if you shock weekly. At that cadence stabilizer accumulation is not a footnote, it is the outcome.

Check price on Amazon

#ad · how this is funded

Questions people actually ask

Is liquid chlorine the same as pool shock?
It does the same job - raising free chlorine sharply - so functionally yes. Chemically it is sodium hypochlorite in water rather than a solid, which is why it adds only salt while granular shocks add calcium or stabilizer.
Which is cheaper, liquid chlorine or granular shock?
Per ppm delivered, liquid chlorine is usually cheaper. Per unit of storage space and per trip to the store, granular usually wins. Work it out for your own pool volume with the formula above rather than comparing shelf prices.
Can I use liquid chlorine in a saltwater pool?
Yes, and it is the best choice for one. A salt generator makes sodium hypochlorite in situ, so adding it directly is chemically identical and adds nothing your pool is not already handling.
Does liquid chlorine raise pH?
Yes, noticeably, because sodium hypochlorite is alkaline. Expect to follow a large liquid chlorine dose with a pH correction - see how to balance pool water.

Sources

Every figure on this page traces to one of these. Where a number could not be sourced, the page says so rather than estimating.

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