Manual Says To Avoid Household Liquid Bleach

[quarky42]

Why does the manual (Caldera) say "DON’T use household bleach (liquid sodium hypochlorite)." and what am I supposed to use in the 3 Step Bromine from the Bromine For Beginners which says that I need to use household bleach to shock the system to get it going. I believe one alternative is to use a non-chlorine shock, but I'd like to understand why I'm not supposed to use household unscented bleach like the Bromine For Beginners thread says. What other Chlorine Shock options do I have? I don't mind spending a little bit more if there is a decent reason, but I'd like to understand what's going on.

I am buying a used Caldera tub with the Spa Frog System in-line. It seems to have been maintained well but I am going to do a thorough Nitro Decontamination anyway and I want to make sure that on my first REAL fill after the Decontamination that I do the best job I can with the 3 Step Bromine Method while still attempting to follow the manufacturer's "rules" assuming they are legit. Maybe I'll stick with a non-Chlorine based shock, but I like learning instead of following blindly.

I have started learning and I'm already making a whole shopping list of things to buy, first and foremost is the Taylor K-2106, Second Filter, SeaKlear Spa System Flush, Hose Prefilter (semi-rural water system, so better than a well, but probably more metals and calcium than the city.), maybe a digital meter as a sanity check on the Taylor or as a "quick check" but I need to do more reading to see if any of them are really accurate enough. I'm also buying the Spa Frog cartridges for the minerals and the bromine dispenser, but I really like the idea of adding the initial fill bromine required to set the level without the cartridge and maybe make the cartridge last a little longer, and the shortlist of other chems I'll need to manage the water qualities as per the Bromine for Beginners thread.

I think everything is making sense except that pesky Don't use household bleach versus use household unscented bleach conflict.

Disclaimer: I did a silly thing. I attempted to do a search for Caldera Bleach, Household Bleach, and other variations and I either found nothing or I looked through the staggering results and didn't see anything that addressed my Hot Tub Manual telling me no. So, please forgive me if I missed something. I tried. Really. (I even enlisted Google.)

Thanks!

[chem geek]

They mostly do not want you to use bleach in a chlorine spa that has no CYA in it. That is, they don't want you to use only bleach because then the chlorine level will be too strong and will degrade hot tub covers faster and may have metal corrode faster though usually it's low pH that is more destructive to metal. They also don't want the pH to rise and have calcium carbonate scaling in the heater that can damage it and that can happen if using only bleach and not having the TA low and using 50 ppm Borates (i.e. the pH can rise and some people don't look at the pH as they should). It's far too complicated for hot tub manufacturers to say, "well, you can use bleach if you use Dichlor first or add CYA to the water first or are using a bromine spa so have a bromide bank in the water first". Besides, some of the manufacturers probably don't understand the chlorine/CYA relationship and just know that some hot tub owners who used only bleach ran into problems.

Finally, you should add any concentrated chemical to the spa slowly with the circulation pump running so that the chemical does not settle to the bottom and sit on a spa surface. Bleach is denser than water and while it will stay thoroughly mixed once it gets mixed, dumping it quickly in one place isn't good -- do it slowly with the water swirling.

When I was first suggesting the Dichlor-then-bleach method, I had people lower the TA to 50 ppm but didn't have them add 50 ppm borates. There was one tub owner who didn't pay attention to their pH and it went very high and they also had higher calcium hardness so got terrible scaling. I got chewed out from a spa dealer (on this forum) and is when I looked at adding 50 ppm Borates and emphasizing that the Dichlor-then-bleach method requires checking water parameters, including pH. It's not a set-and-forget method.

It might be interesting for you to call Caldera if they have a direct factory number and ask them why they say that in the manual, though you might not get anyone that really knows the original reason.

[quarky42]

I thank you for the very thoughtful response. Perhaps my "why" was the wrong question to ask, but I think you still addressed my concern. Basically it just made me worry that the manual says "do not" and one of the steps says "do".

I will read more, learn more and then maybe dare try calling Caldera if a direct number can be found. I won't hold my breath in the meantime though.