Why Don't Spa Manufacturers Like Bleach Method?

[lagreca]

Why do spa manufacturers look down on the bleach method?

I've heard it's because it can splash on the cover and damage it. But I can take responsibility and keep the bleach off the cover.

Isn't bleach the same as liquid chlorine, just a much lower concentration? Isn't it also very similar to dichlor, but without the CYN?

[chem geek]

It's not just the splashing of concentrated bleach, but also if you use bleach without first using Dichlor or otherwise adding Cyanuric Acid (CYA) to the water, then the active chlorine level will be too strong and will oxidize skin, hair, bathing suits, hot tub covers, etc. too quickly and will outgas faster so use up chlorine faster as well (the "myth" of chlorine not lasting as long as bromine -- which is only true when there is no CYA in the water).

Bleach is indeed similar to Dichlor but without the CYA. However, their pH upon addition is different and that's another reason the manufacturers and dealers don't want you to use bleach. The pH will tend to rise over time due to carbon dioxide outgassing. If you don't manage this via lower TA and supplemental pH buffering (such as 50 ppm Borates) and you let the pH get too high, then you can get calcium carbonate scaling and can damage spa components such as heaters. Dichlor is therefore easier in terms of not fouling things up either by having too strong an active chlorine level or having the pH rise too much. Of course, the downside is that CYA builds up making the chlorine less effective thereby requiring more frequent water changes.

[lagreca]

What is the acceptable CYA range for using the dichlor bleach method (both the upper and lower end)?

[dlleno]

Lagreca I'm sure you will find the acceptable CYA levels in the stickies, expressed both as a number in ppm and as the total amount of dichlor you use over time. In a nutshell, as you add Dichlor your CYA will rise to a point where adding more is detrimental. when you reach that point, start using bleach instead. Here is a quote from Nitro's method:

The first thing we are going to use to sanitize our tub is Dichlor. Dichlor is actually two things, Chlorine and Cyanuric Acid (CYA). CYA is a chlorine stabilizer, which slows down dissipation from UV rays (sunlight). It also acts as a buffer to hold chlorine in reserve. Having CYA in your tub will stop the chlorine from dissipating as fast while waiting for something to do. However, CYA also cuts down on the ability for the chlorine to sanitize. So in other words, the higher the CYA level, the longer the FC will wait in the tub, but the less effective the FC is. With no CYA in the tub, using bleach would be too strong and not practical to use. So, there needs to be a happy medium. Luckily Chem Geek has come up with one for us. He suggests a CYA of ~20 ppm. Personally I use a CYA of 30 ppm for reasons I won't get into here. But I think Chem Geek would agree anywhere between 20-30 is fine. Where the problem comes in is when CYA gets too high (above 100) after weeks of using Dichlor. Then your FC needs to be really high to get the same sanitation effectiveness. That's why we switch to bleach after we get our CYA to 20-30. Bleach doesn't add anymore CYA.

Why do spa manufacturers look down on the bleach method?

there is of course a business dimension as well, from my experience anyway. spa stores are motivated from a business and customer perception perspective to offer a complete solution, i.e cradle to grave support, service, etc. of the spa they sell you. Some even hold water maintenance classes, which have both educational and marketing value. There's nothing wrong with making a profit, don't get me wrong, but neither is there anything wrong in choosing not to buy. So the spa stores typically line up with one or more big label chemical companies, often with one or more of the high dollar alternative sanitation methods. For example, Baqua was a hot topic back in the 90s. Not too recently the biofilm thing got a lot of attention and so companies lined up with their various offering. Even Silk balance has their high dollar enzyme based cleanser.

Anyway, the stores make money on chemicals so they want you to come back. its not a conspiratorial thing don't get me wrong, but even with 200 loyal customers maintaining their tubs, the spa store won't make much money on chemicals if they advise their customers to get bleach, borax, and baking soda from the grocery isle, use the pool calculator, and shop online for Boric Acid.

Meanwhile the big label companies buy washing soda in large quantities, package it in small containers, label it "pH up" and charge, well, you know. They do the same with Baking soda only they call it "Total Alkalinity increaser" -- again not to deceive people (at least not the honest stores) but to offer a total branded solution to build customer trust. And, to be sure, a great many customers want that: some would not even think of buying baking soda, but prefer that the label says "SpaGuard" on it, for example. Hooray for free markets.

With much enthusiasm, I have to say that using the knowledge I continue to receive here, there is no longer any reason for me set foot into a spa store unless its to talk about servicing my spa ,buying a replacement part whatever. or for example, if I haven't planned my online purchases very well and I need some phenol red or dry acid. I still call them "my" store because they are great folks, stable, good business practices and all of that, and deserve to stay in business. I'll give them business whenever it is warranted. I'm on a first name basis with the owner, and have known the vast majority of the staff in more than one city where they do business over the last 20 years. I just don't by chemicals from them anymore due to the cost.

Today I have a Taylor 2106 and I buy all of my replacement reagents from Amato Industries. Some things (like the 2106 itself) are cheaper via their Amazon outlet; some things like Reagents I find are cheaper from them directly. I purchased sodium bromide from intheswim and SpaGuard products like their stain and scale control (I have metals) from hydropool. Boric Acid from Dudadiesel.

[chem geek]

What is the acceptable CYA range for using the dichlor bleach method (both the upper and lower end)?

I used to minimize the recommended CYA since when it got too high it looked like the risk of hot tub rash/itch/lung increased and I know that the rate of oxidation of bather waste would slow down. However, since that time, I think 20-30 is a bit too low since you want CYA to moderate chlorine's strength and CYA slowly gets degraded by chlorine at the rate of around 5 ppm per month. So now I recommend around 30-40 ppm though there's probably nothing wrong with 50 ppm either. 100 ppm would definitely be pushing it so figure 30-50 ppm is a decent target range.

[lagreca]

I will shoot for 40 ppm CYA for my calculations.

Is it safe to assume that CYA under 30 ppm, bleach is NOT safe to use because it will be too strong?

If so, does that mean I should dose with dichlor (enough to raise FC 10 ppm) every 2 months to raise the CYA back up into safe levels to use bleach?

[chem geek]

Is it safe? Yes. It's just much harsher and could be irritating, will outgas faster so may smell more, and will oxidize your skin, swimsuits, hair faster, corrode metal faster, and degrade hot tub covers faster. But "faster" isn't in an instant. Consider that when you start out using Dichlor after a fresh refill, there is no CYA in the water, but the Dichlor adds some. The equivalent active chlorine level during this startup phase is listed below assuming 104ºF:

5 ppm FC from Dichlor: equivalent to 3.1 ppm FC with no CYA

now with 4.6 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 2.0 ppm FC with no CYA

now with 9.1 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 1.5 ppm FC with no CYA

now with 13.7 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 1.2 ppm FC with no CYA

now with 18.2 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 1.0 ppm FC with no CYA

now with 22.8 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 0.9 ppm FC with no CYA

now with 27.3 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 0.8 ppm FC with no CYA

now with 31.9 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 0.7 ppm FC with no CYA

now with 36.9 ppm CYA, add another 5 ppm FC from Dichlor: equivalent to 0.6 ppm FC with no CYA

So you already know what it's like for the active chlorine level to be higher, though you usually don't start your soak with 5 ppm FC (usually 1-2 ppm FC).

As for dosing with Dichlor on occasion, yes you should dose with Dichlor to maintain the CYA level since it will drop at around 5 ppm per month. You can add some Dichlor every month or two as you suggest.