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New to hot tubs, possible silly question


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Hi folks, my first post on here. 

We had our tub installed on Tuesday and have been enjoying it so far. 

I have possibly a silly question but can't seem to find the answer anywhere, what's the difference between chlorine granules and chlorine shock? 

 

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Any chlorine can be used to shock. Liquid chlorine (bleach) is often sold as "pool shock". Calcium hypochlorite might also be sold as "shock" and is granular but generally should not be used in a portable spa due to the calcium and mixing requirements. Sodium dichlor is often sold as "spa chlorine granules" and is usually not used as shock due to cya (cyanuric acid, stabilizer).

Read this.

https://www.poolspaforum.com/forum/index.php?/topic/23090-dichlorbleach-method-in-a-nutshell/

 

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Shock is not a product, it is a procedure and involves raising the Free Chlorine (good chlorine) level to a certain point to help oxidize organics in the water and destroy combined chloramines (bad chlorine). The level of Free Chlorine needed is dependent on the level of Cyanuric acid (chlorine stabilizer) in the water.

There are 2 categories of chlorine"

Stabilized chlorine (chemicals that are made from chlorine and cyanuric acid, referred to as chlorinated isocyanurates or organic chlorine) :

Dichlor, a fast dissolving granular form often used in spas but it adds 9 ppm of cyanuric acid for every 10 ppm free chlorine added (and the cyanuric acid is cumulative and continued use can lead to overstabilization.

Trichlor, a slow dissolving tablet that is very acidic  so it is more commonly used in pools because the small amount of water in a spa combined with the very acidic trichlor can cause the pH to drop dangerously low.  It is used in a floater or feeder system.

Unstabilized chlorine (non of these contain cyanuric acid and are often referred to as inorganic chlorine):

Sodium Hypochlorite AKA liquid pool chlorine, Liquid Pool shock, Liquid Chlorine, Bleach ( plain unscented laundry bleach with no thickeners,scents, or additives), Clorox. These are all interchangeable, the only difference is the strength and therefore the dosing. Pool chlorine is usually either 12.5% or 10%, Bleach is usually 6% or 5.25% but there are also ones that are 8.25% and 3% so read the label. Avoid the 3% because it is not cost effective. It has the smallest impact on water chemistry and is a preferred source.

Lithium Hypochlorite often sold as lithium shock. This is a fast acting granular product that does not need to be predissolved in a bucket of water and also has minimal impact on water chemistry like sodium hypoclorite. It's biggest downside is the price as it is the most expen$ive form of chlorine. If you go this route make sure it does not contain any additives such as algaecide, copper, clarifiers, defoamers, etc.

Calcium Hypochlorite AKA Cal Hypo or sometimes just shock. This is a medium slow dissolving form of granular chlorine that must be predissolved in a bucket of water and will add 7 ppm calcium hardness for every 10 ppm of free chlorine added. This is better suited for a plaster pool or spa that requires a much higher calcium hardness to help protect the plaster but can cause scale deposits in an acrylic spa, particularity at the much warmer water temperature in a spa than a pool. It comes in different strengths also. The higher strengths (generally (65% - 73%) have less  filler (generally calcium carbonate and calcium chloride) so they have less impact on water parameters except for calcium hardness but they are potent oxidizers (class 3)and have been known to spontaneous combust or explode under certain conditions, and have been responsible for several warehouse fires over the years so they have gotten much harder to find and are much more difficult to ship. The weaker concentrations (48% - 53%) are safe to store and ship because they are  class 2 oxidizers but the concentration of filler can have a greater impact on pH when compared to the stronger formulations.

As with Lithium Hypochlorite, you want a calcium hypochlorite that only contains the calcium hypochlorite and the inert filler. You want to stay away form 3 in 1, 4 in 1, or 5 in 1 shocks or any that contain copper, algaecide, clarifiers, defoamers, or other "extra ingredients".

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Waterbear that is a very detailed and informative reply, thank you.

As I said, we have had the tub just under a week, we haven't been able to use the tub at all over the weekend and when I came home from work today I thought that I would do a water test

First thing I noticed when I lifted the cover was that the water was a little cloudy.

free chlorine was at 0ppm and PH was at 6.2 

after adding chlorine granules and PH up my readings are 

free chlorine 80ppm and PH 7.2ppm

However the water is still the same misty/cloudy look to it.

would this be ok to use ? any advice chemical wise would be more than welcome

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21 hours ago, James69 said:

free chlorine was at 0ppm and PH was at 6.2 

after adding chlorine granules and PH up my readings are 

free chlorine 80ppm and PH 7.2ppm

How are you testing? A pH of 6.2 is dangerously low and can damage the equipment

A FC reading of 80 ppm is impossible. no pool spa test for FC goes that high

How many gallons is your spa and how much of the chlorine granules did you add? Also, what is the ingredient(s) listed on your chlorine granules

21 hours ago, James69 said:

However the water is still the same misty/cloudy look to it.

could be several reasons for this.

Let's start with how you are testing your water (please don't say test strips, they are practically useless).

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Ah, erm, yep, sorry but test Stips

Tub is 2m x 2m and 0.9 deep. 

Supplier said 3600lts and to add 3 cap fulls to a a container of warm water and dissolve the granules. 

I have attached some pics of that may help. IMG_20210126_211833.thumb.jpg.441e2806ff00eee2b9e651ee7cf05d4b.jpg

IMG_20210126_202916.jpg

IMG_20210126_202904.jpg

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On 1/25/2021 at 4:08 PM, James69 said:

free chlorine 80ppm and PH 7.2ppm

  I am guessing from the pictures on your test strip bottle you meant to originally type out TA @80ppm

Just a guess though :)

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3 hours ago, James69 said:

Ah, I see what I did there, was typo, FC 5

TA 80

PH 7. 2

Sorry for any confusion. 

 

Thank goodness! 

First off, get a good test kit. 

4 hours ago, James69 said:

add 3 cap fulls

How big is the cap?

7 hours ago, waterbear said:

pH of 6.2 is dangerously low and can damage the equipment

Will damage the equipment. Not can, will. Just a matter of time.

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