what to aspect when applying TFP on spa

[edwin2014]

Think i got everything sorted out. Did a ahh-some cleaning 5 times.

When testing i got the folowing:

FC 5.0
PH 7.5
TA 60
CH 150
CYA 30
Borates 60
CSI -0.32 (poolpal app)
LSI -0.15 (poolpal app)
CC 0.5

One thing that concern's me is that that the sub is using FC even with no bath load, appr 6ppm/24h.
Water looked sparkling clear the first 2 time's now a little bit misty, just liked very small particles are floating around. Could be because filtering is 2x1 hour, thinking it is getting colder and the tub has to heat up which would equal out the reduced filtering scheme, perhaps not. Filter is clean and 25m2 type. I could try a 50m2 filter but not sure if this would clear up the water.

btw the spa looks anyway so much better than before cleaning and using aquafinesse.

 

[chem geek]

Do you have an ozonator? If so, then the ozone will react with chlorine, usually creating a chlorine demand of 50% but it can be more depending on the output of the ozonaator and how long it is on. With no ozonator, then no more than a 25% 24-hour loss at hot spa temperatures is more typical; lower loss at lower temps.

According to the Artic Spas Owner's Manual, "The system will automatically perform four one-hour filtration cycles per day. After the high speed pumps and blower are run for 30 seconds (probably to make sure they get disinfected at least once every 6 hours) then the pump is run at low speed for the programmed number of hours during which the ozonator is on. (Note that the "Onzen" system they refer to is a saltwater chlorine generator system). If you press the Filter key (or Pump 5) it will show FdXX with XX being the number of hours currently set for the filter cycle duration. I suspect you have that set too high and that you have an ozonator that is using up chlorine too quickly. You should lower this number to reduce the chlorine usage fro the ozone.

 

[edwin2014]

Oi, forgot to mention it is a 2007 model and I doubt if the ozonator has been exchanged. I don't smell any ozon when openening the cover and I read on the internet that the life span is approximately 5 years max. As far as I could trace thw default filtration setting for this model year is 2x 2hr, which I changed into 2x 1hr.
Last days I monitoring the fc consumption. Bit difficult since tub is also used, but it seems to consume a steady 6-7ppm FC over 24 hours.

 

[chem geek]

If you hadn't used the Ahh-Some, then I would have suspected biofilm buildup, but since you've cleaned out the spa thoroughly I'm at a loss to explain the very high FC usage. So how are you getting to 6-7 ppm FC use? That is, what do you raise the FC to and how often?

By the way, when you say no bather load this should not mean the 24 hour period after a soak. There is normally high FC usage after a soak with most of it occurring in the hours right after the soak and most within 12 hours but there is still chlorine usage from bather load up to 24 hours later. So if you do this sort of test you have to not use the spa for a day and then do the test for the 24 hours AFTER the spa hasn't been used for 24 hours -- so a 48 hour interval with no use where you raise the FC at the midpoint of the 48 hour interval and then measure again at the end of the time period.

 

[3dogowner]

Now you've got me scratching my head. Given the delay in the drop of the FC after bather usage (hours), there would seem to be no point then in checking the FC both immediately before AND after usage. You just use the BEFORE usage FC to determine the chlorine dose. Is this correct? Taking into account bather usage, water temp, time interval to cover until next use, your spa's quirky chlorine loss rate, etc.

 

[edwin2014]

Chem geek, you are mention something. My observation is indeed no 48h period. The 6 to 7 ppm usage is stabil but always with a 2p soak for about 1h. Need some time to perform the mentioned 48h test. Will report back.
Btw I'm sure the tub had some biofilm buildup before clean. I could pour in 500ml of 12.5 chloor in the ebening and in the morning a measue stick (did not havethe tf100 that time) did not show any fc at all. Even in doubt if the sticks did work. Now after clean and having the tf100 as mean guide I can say that the stick did work. So before clean the tub consumed more than 500ml chloor during a night.

 

[edwin2014]

O, and the measuring was in both cases right before soak

 

[chem geek]

Now you've got me scratching my head. Given the delay in the drop of the FC after bather usage (hours), there would seem to be no point then in checking the FC both immediately before AND after usage. You just use the BEFORE usage FC to determine the chlorine dose. Is this correct? Taking into account bather usage, water temp, time interval to cover until next use, your spa's quirky chlorine loss rate, etc.

Yes, the goal is to add whatever amount of oxidizer/disinfectant is needed after a soak so that you have a small FC residual for the start of your next soak. There is most certainly no point in measuring the chlorine after your soak or too soon after you add chlorine after your soak. A rough rule of thumb is that with no ozonator and in a hot spa that every person-hour of soaking requires around 3-1/2 teaspoons of Dichlor or 3-1/2 fluid ounces of 8.25% bleach or 7 teaspoons of non-chlorine shock (43% MPS) where the latter is with the Nature² system.

Chem geek, you are mention something. My observation is indeed no 48h period. The 6 to 7 ppm usage is stabil but always with a 2p soak for about 1h. Need some time to perform the mentioned 48h test. Will report back.
Btw I'm sure the tub had some biofilm buildup before clean. I could pour in 500ml of 12.5 chloor in the ebening and in the morning a measue stick (did not havethe tf100 that time) did not show any fc at all. Even in doubt if the sticks did work. Now after clean and having the tf100 as mean guide I can say that the stick did work. So before clean the tub consumed more than 500ml chloor during a night.

So two people for one hour in a hot spa with no ozonator may require around 7 teaspoons of Dichlor or 7 fluid ounces of 8.25% bleach. In 478 gallons this would be around 10 ppm FC so it seems that you were simply not adding enough chlorine to oxidize your bather waste. Again, the rule is to add whatever it takes so that you have at least a small residual (1-2 ppm FC) before your next. The rule-of-thumb for dosing can be a double-check to see if you are adding enough.

 

[edwin2014]

alright, think chem-geek was right.
Did a soak and add chlorine on Friday evening. Measured fc on saturday and adjustedn no soak. sunday evening fc test and added chlorine. 1 hour later i tested and got on 10ppm. tonight (monday) i tested again and got 5ppm. No soak's since Friday evening. So it seems that the very high loss of FC was because of the soak and the regular loss is about 50%. Still on the upper scale of what chem-geek predicted, but not alarming.
Seems that the it is indeed perhaps not enough bleach after soak. I was adding 100ml (3.38 fl ounces) of 12.5% chlorine and this probable had to be about 4,62 (138ml). But i'm sure i was able to get from evening to evening without dropping below 3FC. Lowest i got was 3FC
Could the conclusion be that all is within the to be expected range?

 

[chem geek]

Seems reasonable except the 50% loss is higher than normal with no ozonator. Just see how things go from here.

 

[edwin2014]

I'll keep an eye on the fc loss and with next water change I will also use an aquafinesse cleaning puck. Hoping for good weather. Thanks for input!