The I hate Spa Parties Thread.

[BCHWB]

I changed the water on Sunday because the weather was so nice and the tub's perfect now. No more foam from that first fill and I've finally got everything the way I want it. The wife informs me last night that her sisters are coming again tonight for another go in the spa.

So this morning I was here:

pH 7.7
TA 50
CH 220
Br 4.5

What I did was to raise the pH to 80 (I was going to anyway) with 3 Oz of Baking Soda which raised the pH to the 7.9 range.
I used 1.5 Oz of MPS to bring the Bromine level up to 10 (I actually got 11.5 but it will be 10 by the time they enter) and this dropped the pH back to 7.7

While they're in there, I suspect with an 80 TA that they'll push the pH up to around 8 to 8.1 which will allow me to put in the 4 oz or so of MPS shock for the 3 to 4 person hours of soaking thus bringing the pH back down to around 7.5-7.6.

So basically I have 3 questions...

Am I doing anything wrong here or is this the proper procedure. Is 4 oz of MPS way too much to put in? With a 30ppm bromide bank, it doesn't seem that I could activate all of it anyway.

What do you all do in preparation for your spa parties?

Am I making way to much of this?

Thanks.

 

[PoolGuyNJ]

Bring the pH down a click or two. It will help prevent scale and the sanitizer will work better. I prefer a stable 7.4 pH.

Scott

 

[chem geek]

The rough rule-of-thumb for the amount of oxidizer needed to oxidize bather waste in a hot (100-104F) tub for every person-hour of soaking is around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS). So 3-4 person-hours of soaking would be 21-28 teaspoons or 3-1/2 to 4-2/3 ounces of MPS. So your 4 ounces (volume) of MPS is not out-of-line for that kind of tub use. However, this assumes no ozonator and I thought you had an ozonator in your spa so in theory you should not need to use as much oxidizer. By the way, 4 ounces of MPS in a 350 gallon spa would be equivalent to around 23 ppm chlorine or almost 53 ppm bromine.

Scott, the reason BCHWB raised the pH so high is that MPS is acidic. With standard MPS, adding 4 ounces to a 350 gallon spa with a TA of 80 ppm would lower the pH from 8.0 to 6.6 (and the TA from 80 to around 60). Some spa MPS is somewhat pH buffered, but it is still quite acidic. In my calculation, I assumed a relatively unbuffered MPS that has 2% magnesium carbonate and a pH of a 1% solution of 2.3 (such as SpaGuard Spa Shock which, by the way, is only 31% MPS, not 43%).

BCHWB, instead of using so much MPS to reactivate the bromine and oxidize bather waste, why not use 6% Clorox Regular bleach or perhaps a combination of bleach and MPS (added separately -- probably adding MPS first). That should help prevent the pH from dropping so much.

Richard

 

[BCHWB]

Thanks Richard, it worked out so that I had 4 drops of acid demand to get to 7.4 (K2106) when they all got out of there. There were only 3 so it wasn't that bad. They were in for an hour I use 1oz per person hour rule as I do have an ozonator and 7 Tsp of the shock I use weighs 1.2 Oz so I'm shooting a little under. 3oz of MPS brought the pH right back to 7.5 and brought the TA down to 70 or so (Dark red endpoint at 6 drops, bright red at 7). I didn't measure bromine but I'm sure it was over 20. There's still 7.5ppm residual in there now 24 hours later without the floater in it.

The snow is falling lightly and it's in the 30s out and my 3 little girls (7, 9 and 11) want to go in with their mom as a new "New Year's Tradition" uggh. I'll go get the shock...

I'm making them shower first!

 

[BC]

You gotta love it....all the enjoyment everyone is getting out of the tub! Makes the work you put into it worth the while. BTW - when is it your turn?
Barry

 

[BCHWB]

I only go in once in a while. I'm actually not a big hot tubber but I've taken on the maintenance duties as a sort of hobby. I usually just sit by the chimenea and drink a beer while the rest of them are in there.

I did have a sort of breakthrough recently, like last night while I couldn't sleep. My procedure has always been to shock and adjust the water once the occupants have exited and my tub's got a pretty capable 24 hour circ pump which produces pretty good flow so the chems distribute pretty quickly but the water in the rest of the system (between the 2 jet pumps and the jets) is now not subject to any flow and I'm not sure how effectively the bromine level will equalize without any flow present. Also, in the winter, this area of the system must drop below the 102 mark that I've balanced for into the 80s or 70s thereby going out of balance... I'm not sure what could be done about this but it seems that this will happen to any spa left in the cold and unused for a couple of days.