# strength in Chlorometric degrees

#### Nitrock28

Bronze Supporter
Hi !

I would like to know with a little more depth what strength is the chlorine I add to my pool.

I live in Belgium and they display the strength of the chlorine in degrees (°) as shown here :

They also sell 50° strength in a 25L container.

After some research it appears that this corresponds to Chlorometric degrees, which are about 3.15 times the weight percentage of available chlorine, which can be converted to available NaOCl using the molar masses ratios.

To then convert that to trade percentages, which is what is needed for poolMath, I need the specific gravity of the bleach. As I understand it, this value depends on the production process of the chlorine, and is representative of the quality (lye content)?

Can anyone tell me if I'm on the right track, and if there exists an easy way to estimate the specific gravity of 50° (=15.09% by weight of NaOCl) chlorine ?

I'm also trying to figure out ChemGeek's PoolEquations spreadsheet, and I'm trying to adapt the levels to fit my bleach concentration. So any help is welcome

Thanks !

#### tim5055

TFP Expert
Where is Matt when you need him.....

#### JamesW

TFP Expert
50 Chlorometric degrees is 15.85 % (Trade percent). When you enter the percentage in the calculator, it automatically changes to trade percent for any value over 9.0%.

If you're using 50 chlorometric, enter 15.85 in the percentage and it will work.

#### JoyfulNoise

TFP Expert
Platinum Supporter
Sorry. Busy morning. JamesW nailed it right. The conversion is 1 CD = 3.17gram/liter free chlorine.

As for Richard's spreadsheet, you'll have to email him directly about it as it is not a tool TFP uses regularly (too complex for the novice user). A

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#### tim5055

TFP Expert
50 Chlorometric degrees is 15.85 % (Trade percent). When you enter the percentage in the calculator, it automatically changes to trade percent for any value over 9.0%.

If you're using 50 chlorometric, enter 15.85 in the percentage and it will work.
Thanks James!!!!

#### Nitrock28

Bronze Supporter
Sorry. Busy morning. JamesW nailed it right. The conversion is 1 CD = 3.17gram/liter free chlorine.

As for Richard's spreadsheet, you'll have to email him directly about it as it is not a tool TFP uses regularly (too complex for the novice user). A

Sent from my iPhone using Tapatalk
Oh I see where I got it wrong, I (mis)read somewhere that it was 1 CD = 3.17 gram/Kg, or 0.317 % by weight. I think that's where my confusion about specific gravity comes from.

Thanks a lot !