New to us hot tub

[JAFroese]

My husband and I bought a used hot tub a few weeks ago. I'm estimating the tub to be approx. 320 gallons. I've read through how to chlorinate your spa several times but I'm finding myself much more confused about maintaining it than our pool.... To begin we superchlorinated and ran ahh-some. Or fresh fill results were FC 0, PH 7.6, CH 0, TA 100. I added calcium, cya (target 20 ppm), acid, and chlorine. I managed to get the TA down to 60, and CH to 100 ( will add a bit more calcium to raise a bit higher). I brought the FC to 12 ppm and by evening it had dropped to 4 ppm. My husband was anxious to try it out, so we enjoyed our first soak, approx. 1 hour. I tested again right after our soak and FC was down to 2, so I added enough chlorine to bring back to 6. However, today our FC was already down to 1.5 prior to anyone soaking. I was nervous that if it was only 1.5 prior, that we would drive it down to zero during our soak (4 young boys, 2 adults) so I added enough chlorine to bring FC to 6 prior to the soak. Once we were done FC was 4 and then 3 hours later was down to 2.

So my main questions are:
-when do you normally test your tub? Before and/or after soaks? (Our boys will most likely be going in and out of pool/hot tub several times during day, I would like to be testing once a day at the most)
-is my FC dropping too quickly? Or is this expected? (I don't believe we have an ozonator)
-should my chlorine target after soaks be higher than 6ppm?
-if my boys are going in/out of tub several times during the day, do I need to be adding chlorine after each soak?

 

[pooldv]

Congrats on the new tub. We love ours, after 18 months we still use it almost every day.

Strange that your CH is 0, but you are adding and it is going up so that is good. Don't skip adding the borates, they add value. More on that here, Borates - Why and How

What you really need to try to figure out is what your person hour chlorine consumption is and add that every time you get out. 4 people 30 min is 2 person hours. If your person hour chlorine usage is 1/8 cup of bleach then add 1/4 cup when you get out.

I would bump CYA to 30, it gives you a little more latitude on having higher FC levels. You can have up to 12ppm and still be safe and comfortable.

Now, your questions,
So my main questions are:
-when do you normally test your tub? Before and/or after soaks? (Our boys will most likely be going in and out of pool/hot tub several times during day, I would like to be testing once a day at the most)
test before and get the level up around 10 and then add your person hour amount after

-is my FC dropping too quickly? Or is this expected? (I don't believe we have an ozonator)
that seems pretty normal to me, a tub is a LOT smaller and a LOT hotter than a pool. People per gallons is way higher and chlorine consumption will be a lot higher than a pool.

-should my chlorine target after soaks be higher than 6ppm?*
Your target after a soak is to add enough chlorine to oxidize all your body waste and have 6 left.

-if my boys are going in/out of tub several times during the day, do I need to be adding chlorine after each soak?
it is a good idea to roughly keep track of the person hours and add as you go

Use your OTO chlorine tester and learn what shade of yellow 2ppm is and use that to stay above 2ppm at all times. I have 1/4 cup measuring cup, a gallon of bleach and an OTO test kit sitting on a table by the tub.