Noob question. Going on vacation so....

[Jfk3rd]

Hey everyone. I've been lurking for a little over a month now reading and learning, trying to get set up to use the BBB method in my hot tub. I haven't started doing it yet, still just using the dichlor, ph & alk up/down the spa store sold me, but have a question I need answered so I thought I would go ahead and ask here. I am leaving out of town next weds for Cozumel and will return the following weds. As of now even if we aren't using the tub I have to add about .25oz of granuals a day to keep the ppms up around 2-4. I was thinking about shocking the tub to 10pm the morning we leave, don't head out til about 10am, and running the jets til the water gets back down around 6 or so before putting the cover back on. My question is there anything else I can do to keep the tub from falling below 1-2ppms before we get back?

Here are my test results from this evening.

Hot Springs Sovereign 355g tub.
Water temp at 95* right now for the summer and in summer heating mode. Also using a thermal blanket to help evaporation.

FC___4-5
Ph___7.8
TA___70
CYA__50

 

[Zadd]

Keep sunlight off it and have a friend put another 10ppm half way through your trip. Turn off heater also may help.

 

[duraleigh]

If you run the FC up to 10 ppm or so (fine with a CYA of 50), it'll probably still be around 6 ppm when you return. If you have a clean tub (no organics) and you eliminate the sunlight, there is nothing to consume your chlorine.

 

[Jfk3rd]

Do you think I could start using bleach since my CYA is at 50 or should I just wait until the next drain/refill?

***edit***

So I was bored and decided to test the water again. Got the following readings.

FC. 1
TC. 2
pH. 7.6ish
TA. 70
CH. 150


Couple of things. When I did my CH test I got specks in my vile. Don't know where they came from. Saw them as soon as I started the drop by drop to turn blue test.

Then per the pool calculator I decided to add bleach for the first time! Hope I didn't screw up. lol

***edit the edit***

Work perfectly. :-D Brought the FC right to the 3ppm I was shooting for. I will test again first thing in the AM to see how much chlorine it uses in a short period and report back later.

 

[ChrisL]

You can also lower the temperature in the tub. Bringing the temperature down from 100 to 80 will significantly cut down on chlorine demand.

 

[xanadu]

A week is not a long time to leave the tub alone. Just make sure your levels are uo to snuff and turn the heat down. Don't over think it.
I have a large hot tub for over 6 yeas now, and never had issues with leaving it for a week or while on holidays. I just make sure its bang on before I leave, close the cover tight, and away I go.

I use chlrorine, not bromine.

 

[chem geek]

The only issue would be if you have an ozonator since ozone reacts with chlorine and in many spas with ozonators it has the chlorine demand increase to 50% per day so after a week less than 1% of the chlorine will be left. Lowering the temperature will help somewhat, but it will still be a high loss rate. Even at a 25% daily loss rate, after a week less than 13% of the chlorine will be left though that's something that could work (i.e. 10 ppm FC down to 1.3 ppm FC). If you don't have an ozonator, there should be no problem having the chlorine last enough during the week.

 

[BoDarville]

When I did my CH test I got specks in my vile. Don't know where they came from. Saw them as soon as I started the drop by drop to turn blue test.

This is actually quite common - nothing to worry about. Likely cause is magnesium coming out of solution. Magnesium is generally not a concern in pools.