Yes I would probably agree CYA down 10 probably due to filling and a bit from being oxidised out.* i got that bit right!*
Phosphate down 0.5 doubtful H2O2 would effect it, *I think it must have ben this, that the lowest its been all summer - when I add ore H2O2 and test the water I’ll report back! *however interestingly as it’s food for algae they actually consume it, often though they leave the byproducts of ammonia which causes a massive chlorine demand before you can get the free chlorine level up to normal levels. okay not great
7.5ltrs of chlorine (Brico shed eau de javel) is just the dose to give you free chlorine level of 10ppm which is not the shock level. Shock level would be 45ppm of chlorine (33ltrs) i realise that is a massive amour of chlorine, would it take a long time to dissipate (apologies wrong word ) before it was safe to swim?
Free chlorine is the measure of the chlorine in the water, not combined chlorine (chloramines). CYA binds to the chlorine reducing the loss of chlorine to sunlight. The actual active sanitiser in the water is hypochlorous acid and hypochlorite ions. We know from chemical tables of equilibrium chemistry (O’Brien 1972) love that paper … now anyway that around 99.98% of the chlorine is bound to CYA *I see the problem with the CYA now!- needs to be lower -as you explain below *producing a very low active hypochlorous/hypochlorite in the water so we add additional chlorine to produce a sufficient active hypochlorous/hypochlorite solution to kill algae and bacteria.
That means with 10ppm of chlorine in the water with 113ppm of CYA there is roughly the same active sanitiser level as a pool with 1ppm chlorine and 0ppm of CYA. An indoor commercial pool is unlikely to have CYA in the water but may have 3ppm of chlorine in the water. That is a very high level of active sanitiser roughly equivalent to you running your pool on 30ppm of chlorine with 50ppm of CYA!
*weird , but I think I get it… I have CYA, there’s nothing I can do about it, so I have to have a much higher chlorine ppm than a public pool , but not much of my chlorine is free, because there is so much CYA - *
The lack of understanding of this chemistry is rife from country to country and is only just being taken on board from peer reviewed chemistry of 1972. I am fortunate to have learned this from a chap known as ChemGeek, Richard Falk, to whom I am most grateful.sound like a most excellent man
If you add more chlorine than needed some of the CYA will be slowly oxidised Ah-ha the chlorine will lower the CYA part, that I hoped would be my savior but darn this is way more expensive route than emptying and replacing the water. You really need a 50% water change, *later in the year unfortunately * There are enzymes that can be added to the pool which eat CYA but results are variable and there must be absoutely no sanitisers present in the pool.and there are…
TAC, don’t worry abot 105ppm you just get the pH rising a little easier than with a level of 40-80ppm.got it
The peroxide 20-30ppm sounds right, I didn’t comment about the PMS earlier but I was puzzled as PMS is peroximonopersulphate another popular non chlorine product but not H2O2 glad you have got the correct test level seems to be around 25ppm 36hrs after adding approx 7.5 ltrs.
You will not be able to use chlorine until the H2O2 level is near 0, if you do the H2O2 will just oxidise the chlorine out as it is a stronger oxidiser stick with the peroxide for the next three weeks then . That’s why I really do not like pool shops that sell this as a solution. Converting back means your pool can go swamp like for a bit and you’ll normally need plenty of chlorine to get rid of the peroxide remenant. roughly , very roughly how much -50ltrs? and how long would that be unswimmable? - 3days ? 7 days ? 2 weeks?
You can’t use a salt chlorinator as you rent the pool to paying guests it’s not allowed. exactly
OK you must be bored to tears by now! nope very very enjoyable, thanks