Water Change

[Barry J]

I have a jacuzzi J365, and the spa store told me to change the tub water every 4 months. Is this needed???,,, when or if any , when should I change the water. I live in Massachusetts, if that matters.

Thanks

Barry

[Greenhorn]

There is a formula for this. I am interested in it also. I have a J375 that has been running for one month now, and the water is definitely less sparkly then when I originally filled. Our tub gets used every day by at least two family members during the week, and sees all 5 of us many times during the weekend. This loss of clarity doesn't bother me much, but what other factors does a person look for to determine a drain and refill? Will the water start "eating up" more bromine or chlorine when it's near the end of it's hot tub life? I'm sure chem geek has the answers for us!

[chem geek]

The rule used for commercial/public spas is the following formula:

Water Change Interval (in days) = (1/3) x (Spa Size in Gallons) / (# of Bathers Per Day)

The assumption is likely to be for a roughly 20 minute soak so the formula in person-hours would be:

Days (Dichlor-only) = (1/9) x (Spa Size in Gallons) / (# of Person-Hours Per Day)

This rule-of-thumb seems to work well for Dichlor-only spas where the buildup of CYA makes the chlorine less effective with continued use/dosing. However, for those using the Dichlor-then-bleach method, they seem to get about twice as much time out of the spa between water changes so that formula would be:

Days (Dichlor-then-bleach) = (2/9) x (Spa Size in Gallons) / (# of Person-Hours Per Day)

Using Greenhorn's data and assuming 20 minute soaks, this is an average daily bather load of ( (20/60)*(2 people)*(5 days) + (20/60)*(5 people)*(2 days) ) / (7 days) = 0.95 person-hours per day. For Dichlor-only, this translates to (1/9) x (375 gallons) / (0.95 person-hours per day) = 44 days (around 1.5 months) while for Dichlor-then-bleach it would be double this or 88 days (around 3 months). If the soaks were longer than 20 minutes, but still at hot (104ºF) spa temps, then the times would be even less.

Now the above assumes that there is no ozonator. With an ozonator it is able to oxidize additional bather waste beyond what chlorine is able to do so could result in longer times between required water changes.

You are correct that as the water is getting closer to the time that it needs to be changed that it will either start to look dull/cloudy or it will have a higher than normal daily chlorine or bromine demand. This is due to a buildup of slow-to-oxidize organics.

You can't just look at a rule, however, and should really be looking at your water quality. If you've got dull/cloudy water or if you have high chlorine demand and these issues are not able to be resolved through usual means of adding enough oxidizer, then a water change is needed.

[Barry J]

Our water is pretty clear, we use spa 56 twice a week, defend once a week and a cap full of renew each time we use it. It's been 5 months now since last change

[chem geek]

You didn't say how often you use the spa. How often you soak, how many people, and for how long for each soak. I also need to know if you have an ozonator. Do you have Nature² because the Leisure Time Renew that you are using is non-chlorine shock and not a disinfectant by itself. The Spa 56 is Dichlor is a disinfectant and twice a week is probably OK if you're using enough Renew for your bather load.

I would say that if your bather load is low you should still probably change the water after 6 months. If you let me know your bather load, I can give you a better idea.

[Greenhorn]

Thanks, chem. I am using bromine in our tub. I can assume that a bromine tub will not be as clear as a dichlor-bleach tub, correct?

[chem geek]

Yes, a bromine tub doesn't stay as clear unless you use chlorine as an oxidizer periodically, but that seems to be what you are doing which is why it is lasting as long as it has. Bromine is a good disinfectant but not a very good oxidizer. Chlorine is better for oxidation (ozone is even better). Non-chlorine shock (MPS) is sort of in between but it oxidizes some different chemicals than chlorine so the combination is reasonable for a bromine spa. So it sounds like you are on the right track and have done well with your spa.

[mrwrick]

I have just drained my 350 gallon 1990 Hot Spring Classic F spa (after using Dichlor as the disinfectant and seeing the CYA get real high). I used Ahh-Some, then SeaKlear before i drained it. Green scum came out. I added water to cover the jets to rinse and redrained. My question is regarding the remaining water that has not drained from the wells of the 2 moto-jets, so I suspect there is extra water hiding in plumbing that has not drained. It has sat unfilled and untreated for 3 days since being drained since I needed to leave it and shop for some parts that need to be replaced before i refill it. How do I get rid of this untreated standing water so it will not adversely affect the spa plumbing and the refill? Do I need to disconnect all plumbing to pumps and heater to get rid of more of the old water? Will that do it? Should I refill and treat the new water before I tackle parts issues? I need to remove and test/replace temperature components to figure out why it will not heat back up. I was told my spa heater control was unconsciously/stupidly turned all the way up by an unsupervised guest, then it sat overnight and was found with very, very hot water in the morning, so it probably overheated and blew the thermostat, high-limit sensor or spa limit sensor or heater or some combination. Thanks

[Kimberly Dukes]

 

Yes, a bromine tub doesn't stay as clear unless you use chlorine as an oxidizer periodically, but that seems to be what you are doing which is why it is lasting as long as it has. Bromine is a good disinfectant but not a very good oxidizer. Chlorine is better for oxidation (ozone is even better). Non-chlorine shock (MPS) is sort of in between but it oxidizes some different chemicals than chlorine so the combination is reasonable for a bromine spa. So it sounds like you are on the right track and have done well with your spa.

 

Yeah Agree @Chem you really Rock in Pool industry .

Bromine cannot clear water unless we use Chlorine I do this by practically .