Slow chlorine vs Liquid

[RonPace]

Hi everyone

In France we have a product, chlor lent, that is large slow dissolving 200g tablets of chlorine. I am sure they are all over the world (?). I am interested to know how much active/effective chlorine is in these tablets compared to the liquid 9.6% 'chlorine' off the shelf.

Am I right in thinking then that for a 20L container of pool chlorine, 1.92L is chlorine and the rest water? If so, is this effective chlorine more or less than the chorine compressed into 1kg of these large tablets?

[Teapot1]

The active level on the galets is higher, I actually can't remember but maybe 37% its usually on the tub. However that is not the whole story. Galets of all forms except calcium hypo also have a lot of cyanuric acid stabiliser in them, more in dichlor than trichlor hence the difference in price. Once you get to the required level of cyanuric acid stabiliser you should stop using galets or you'll end up having to partially empty and refil with fresh water to dilute the stabiliser.
Whilst eau de javel in Brico sheds is cheaper at €12-13 that is generally a 1/3rd of the price of galets and no build up of CYA stabiliser. CYA stabiliser controls your pool more than the pH or chlorine.
Do you measure the stabiliser, not with dip strips as they are hopeless for that, simply not accurate enough.

[RonPace]

Thanks!

Yes, I measure the CYA with tablets in a scuba test chamber. This year it is low.

I am never good with adding these things - stabiliser and Ph plus. Mentioning this to a chap in the store suggested that for stabiliser gradually add these tablets and the readings will get higher, then if I like using them, change over to tablets without stabiliser in them.

I am just interested how effective they are. When it gets really hot, as it can here, I have in the past thrown in extra cups of liqui, as you say, navel just for safety and to 'help' the chlorinator. This year, I wonder if I just pop a couple of tablets in the skimmers. Much easier, and if they have more effective chlorine, then nothing to worry about!

[RonPace]

It won't let me edit!

Above should read javel and not navel ! I must switch off this pesky spell thing...

[Teapot1]

Adding pH + is that something you do regularly?
What is the Alk level and CH?
Roughly where are you, I worked across a lot of France and some areas had incredibly soft water with 27ppm Alk, whereas my area of the Loire its hard water and high Alk. Chorinators usually give a pH rise so hope you can understand why I asked.
Puting galets into skimmers is not a good practice as they are very acidic and when the pump turns off they continue to dissolve and can harm plumbing and pumps etc. Better in a floating dispenser.
You pool shop, the only formulations without CYA are javel and Calcium hypo, all the sodium hypo formulations have CYA in them. Dont ever mix cal hypo with sodium hypo they can explode. Ok in the water.

[RonPace]

....Dont ever mix cal hypo with sodium hypo they can explode....

Like it!!

Now I am confused (easy done) - Chlor tablets in a tub marked 'with stabiliser' are Sodium Hypo?And tablets marked 'without stabiliser' are Calcium hypo?

OK, you know the next question...

Why not manufacture using just one of them and solve the explosion risk..?

[RonPace]

Ph+ usually after prolonged rain. It needs so little which is why I get it wrong. I started by putting too much, then tried to compensate and ended up in a battle! I have it down to a fine art now though.

[Teapot1]

Now I am confused (easy done) - Chlor tablets in a tub marked 'with stabiliser' are Sodium Hypo?And tablets marked 'without stabiliser' are Calcium hypo?

OK, you know the next question...

Why not manufacture using just one of them and solve the explosion risk..?

Yes to the first paragraph.
Calcium hypo increases calcium in the water, obvious so if you are in a hard water area like me you get a lot of scale build up so sodium hypo is a better bet.

What are your Alk and CH? Some areas of the Dordogne have very soft water (Jumiliac) sp for example.

[RonPace]

Ah, that is interesting! I have learned something!

So for me, it will have to be the sodium version with stabiliser. That is a pity!

Thanks for the explanation though!