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Just Did A Decontamination And Want To Learn Dichlor/bleach


Leeboy

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I just did a decontamination on the weekend , and want to learn the basics of dichlor then bleach . I have been running floaters ( trichloroethane tabs) with arctic spa chemicals ( boost, refresh etc) it's so hard to maintain the optical readings. I'm ordering a k2006 kit but will take a bit to get to Canada . So, I'm stuck with the blue bottle of strips for now. The problem is I don't understand the % and amounts etc as explained in the sticky . I have a 450 gallon tub set to around 100. It's usually just me using it with the odd guest. I always shower right before going in due to my job. So after the decontamination , I have around a 10FC level and my TA look good an PH look good . So... Where do I start ? Thanks

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You can let the chlorine drop on its own since you only need 1-2 ppm FC to start your soak. If you used stabilized chlorine (Dichlor or Trichlor) then you already have some CYA in the water. You then just add Dichlor or bleach after your soak. You use Dichlor as your chlorine source until you've cumulatively added around 30-40 ppm and then you switch to using bleach after that. About once a month, you use Dichlor after one of your soaks.

As for how much you need, the real rule is to add whatever is necessary so that you end up with around 1-2 ppm FC at the start of your next soak. How much that is depends on how long you are soaking, how many people are soaking, the water temperature, and whether there is an ozonator. One person-hour of soaking usually requires around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach (3-1/2 fluid ounces of 8.25% bleach) or 7 teaspoons of non-chlorine shock (43% MPS) to handle the bather waste and this assumes no ozonator.

If you have an ozonator, then it won't be easy to maintain your spa using chlorine unless you soak every day or two since ozone depletes chlorine.

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If you are looking at Clorox unscented bleach, not the "Outdoor" or "splash-less" or "scented" varieties, it should say 8.25% sodium hypochlorite on the label in the ingredients section. Yes, you use less for the concentrated which is why I gave that quantity referring to 8.25% bleach (that's the "concentrated" amount). See this image for what you should look for on the bottle.

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I have non chlorine shock, ( refresh) , but to simplify things , would you suggest dichlor /bleach only? Also, I have been reading your other posts , and I notice you talk about borates. What are they and will I need them ? I don't have a ozonator .

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If you already have non-chlorine shock you can certainly use it as a supplement to help oxidize bather waste after a soak, but you still need to use chlorine as a disinfectant. So if you want to use it up you can just split some of your post-soak dosing with non-chlorine shock and chlorine. They work fine together.

The borates are to provide additional pH buffering since you want to minimize pH rise and you do that by lowering the TA level to around 50 ppm by adding acid and aerating (at low pH around 7.0 or 7.2). The easiest way to add borates is by using boric acid, if you can get that in the UK. Europe has banned it except for certain uses because in concentrated form and overdosing it has reproductive side effects. You can read more about the EPA results in the thread Are Borates Safe To Use?. You might be able to find it at a good chemist (Boots or Lloyd's Pharmacy) or at Tesco's or here. I guess the UK hasn't restricted it as much as other parts of Europe.

So after a water change or whenever you are ready to start the Dichlor/bleach method, you first lower your TA with the acid/aeration technique and then you add 50 ppm borates (technically 50 ppm boron) where you can use The Pool Calculator to calculate dosages. For 450 gallons, you'll need around 487 grams (say 500).

You'll start off using Dichlor until you get the CYA to 30-40 ppm so after adding somewhat less than 40 ppm FC cumulatively over time. After that, you switch over to using bleach instead. You then use Dichlor just once a month to maintain the CYA level since it slowly drops. You add whatever amount of Dichlor or bleach that is needed after a soak so that you measure 1-2 ppm FC before your next soak. If you aren't soaking every day or two, you'll need to add chlorine in between soaks -- it won't take very much since with no ozonator the chlorine will likely drop by 25% or less every day (with an ozonator it can be 50% or more loss every day).

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