Question about "residual chlorine"...

[pg_rider]

So on the one hand I always read that "you should always have an acceptable level of residual chlorine (3-5ppm) when using your tub", and on the other hand I read about the "Vermonter" method and how, by the time you're ready to use your tub the next day after adding dichlor after your previous day's soak, there will be NO residual chlorine.  These two approaches seem contradictory -- am I missing something?

Hypothetical -- I soak for 30 minutes on Monday night and add enough dichlor when I'm done to have a 3ppm residual after 20 minutes.  When I go to soak Tuesday night would I have 0ppm if I were to test prior to soaking?  If so I'm assuming it's still safe?

[Gomboman]

Yes, it's a little confusing. Most of us here follow the Vermonter method so you're not sitting in a chemical bath. At home, you'll probably be safe following this method since you know who you are soaking with.

The conservative approach would be to always have residual chlorine in the spa. Your spa manual will probably outline this method because it is safer. You definitely wouldn't want to soak in a public spa or with strangers without any chlorine.

You should be fine adding your chlorine after you use the spa at home if you follow the Vermonter method. If you were going to have a spa party, I would add a little chlorine for insurance.

[RobRoy]

Where do I get info on the Vermonter method?

[drewstar]

Rob, it's on Spa Docs site RHtubs.com   But I'll be D@mmned if I can ever actually find it when I am looking for it.

I follow the "intent" of his method, but not exactly.

The main thrustfor me  is to raise your Cl to 5pm after soaking to sanitize the spa. The chlorine should drift down to very low levels (less than 3, more like 1 for me) by the next day. This way you keep the spa clean, but do not soak in heavly chlorinated water. It works well for me, and many others report great results too. I'd recomend giving it a try.

I disagree with the statement "you should always have an acceptable level of residual chlorine (3-5ppm) when using your tub".  I don't belive it's necessary.  I think many state health codes require these levels for public and comercial pools and spas, but a well maintined private hot tub, i don't think it's needed.

Funny though....I keep my pool at 3-5 pmm constently and am happy. But if soak in the hot tub at those levels, my skin gets  irrated. Could the heat be the key?

[svspa]

Agreed the conservative approach is to always have some residual, but when you are in control of your tub and you know your tub has been at zero for a very short period of time you shouldn't be concerned.

If you went away for a few days and came back to zero ppm free chlorine in your tub, you would probably want to dose first, soak later.

If you came back to that situation, gave your tub a shock dose and the next day had zero ppm residual you can probably surmise your tub wasn't very clean (high chlorine demand). If you had a free chlorine residual for days after your shock dose you probably could surmise your tub was pretty clean (low chlorine demand).

That's the good thing about the dichlor routine, you should be able to determine with pretty high confidence how clean (or dirty) your tub is.

Steve