What sanitizer should I use in my Pool or Hot Tub?

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
An excellent summary!

I think that the recommendation of not using lower levels of sanitizer when using copper and silver ions is a bit extreme, at least for pools. Killing most bacteria is very easy and requires a very small amount of sanitizer. It's the algae that is harder to kill and is usually what requires larger levels of disinfecting chlorine. With copper keeping the algae at bay, I think lower chlorine levels are OK. You still have to have enough Free Chlorine to allow for the reserve needed when chlorine gets used up (even locally) and perhaps that is what the studies and recommendation are about, but that's a different issue than needing enough to kill bacteria quickly.

Now spas are a different matter, at least with regard to the bacteria, Pseudomonas aeruginosa, that causes hot tub itch. That needs higher levels of chlorine to kill and I do not know if silver is even effective at all against this bacteria.

Anyway, I'm no fan of copper/silver ions as they are expensive and don't really save on anything. If you want to fight algae, using Borates is a better way to go and it cuts down on the consumption of chlorine (especially in pools -- we don't know yet for spas).

Richard (chem geek)


Thank you for the compliment. I intended this sticky as a primer for newbies so I don't want to get into any technical discussions about whether .5 ppm FC is enough and the kill times required for cryptosporidium when using copper and silver, which is why I didn't post any links to the research. I am just trying to give an overview on the choices available. You and I both know that a lot of new pool owners get stuck with a lot of unnecessary and expensive chemicals and equipment when all they really need is some bleach, baking soda, and borax! :contract:


LifeTime Supporter
Apr 3, 2007
East Tennessee
I agree with waterbear about the use of lowered chlorine in pools with mineral products. When I was pool stored in to a Nature 2 feeder I looked hard at this product and found it a waste of my hard earned money and a possible unnecessary exposure issue for my family.

Good work on the info waterbear. I was gonna do one but you beat me to it.



Well-known member
Jun 22, 2007
Atlanta, GA
I added Borates to my spa to 50ppm. I am running a chlorine spa. My CYA is around 50ppm as well, could be 40 by now. I lose 50% per day in the sun, so I add about 2-4oz of bleach each day. My FC has dropped as low as .5ppm and my CC's have yet to be above 0ppm. My spa runs better than my pool. I think the Borates have much do to with this. They give me some "forgiveness" for when I let the chlorine get to low. I've been keeping my spa hot for the last couple of days without incident. Wish my pool was this easy. I suspect some of the easieness is caused by running the spa in low speed 24 hours a day, where the pool only runs 6 hours, though I just changed the schedule to 11 hours. We'll see if that makes things easier.