Aqua Finesse question

[jbequer]

Using Aqua Finesses, is it ok to use any type of Chlorine Mini tabs? Since the kit never has enough of the mini tabs to last. If so, what is a good one to get?

[chem geek]

AquaFinesse uses Trichlor tabs which most spa manufacturers say not to use because Trichlor tends to dissolve too quickly in hot spa water, is acidic so if the floating feeder parks itself in one place then the acidity can damage spa surfaces, and the floating feeder has to be sealed at the top or else the chlorine outgassing from the Trichlor will damage spa covers.

I do not know if the Trichlor pucks from AquaFinesse have anything special in them to work better in spas or if it is just their floating feeder that is special (i.e. sealed on top and able to be dialed down substantially).  This MSDS says the Trichlor is 60-100% so it could contain other chemicals, though I suspect it's pretty much standard Trichlor tabs.  I think it's the Slow-Release Dispenser that is critical.  Of course, you'd need to get Trichlor pucks of roughly the same size or else they may not dissolve at the same rate.

[jbequer]

Ok, little confused about the aqua finesse..
 The guy who set up my spa told me to only use only 1 cup of the liquid and three of the granular chlorine once per week. He said he does this to save money on the product, he said he does this on his spa and it works great. I have 375 gallons, on the bottle it says to use 10 oz (two cups) of the liquid once per week.
Is one cup enough ? And is three of the granular chlorine too much?

[chem geek]

The AquaFinesse system used the way you describe with chlorinating granules only once per week will not be disinfected and is why it is not an EPA approved system unless chlorine is maintained throughout the week.  How much is "three of the granular chlorine" -- three what?  If it's teaspoons then 3 teaspoons of Dichlor in 375 gallons is 5.5 ppm FC and will not last through the week if you are using the spa.  It's enough to handle a little less than one person-hour of soaking, if you have no ozonator.  After the first soak, you won't have any chlorine in the spa until the next weekly dose.

The AquaFinesse liquid has surfactants to help prevent biofilm formation, but there is nothing to actually kill bacteria.  That is what the Dichlor is for.  The Mini Tabs were slow-release chlorine (Trichlor) to maintain a chlorine level at all times.  If you don't use those, then to disinfect the spa you'd need to manually add chlorine every day or two.  In between soaks it won't take much chlorine, perhaps 1/4 to 1/2 teaspoon of Dichlor per day depending on whether you have an ozonator.

[jbequer]

Thanks for the reply. What is your recommendation on how much to use?

[chem geek]

You should add whatever amount of chlorinating granules after each soak that is needed so that you still have a 1-2 ppm FC residual by the start of your next soak.  If you soak every day or two then that's just adding chlorine after each soak.  If you soak less frequently, then you'd likely need to add chlorine in between soaks (this is why some people use bromine since tablets in a feeder slowly dissolve to maintain bromine in between soaks).

If you have no ozonator, then the rough rule-of-thumb is that every person-hour of soaking in a hot (104ºF) spa requires 3-1/2 teaspoons of Dichlor or 3-1/2 fluid ounces of 8.25% bleach or 7 teaspoons of non-chlorine shock (MPS) to oxidize bather waste.  The non-chlorine shock is for bromine spas or when using the Nature² system that uses silver ions and is an EPA-approved non-chlorine system (the other EPA-approved non-chlorine, non-bromine system is Baquacil/biguanide/PHMB).  If you have an ozonator, then you may need to use roughly half these amounts after each soak, but would need to add roughly twice as much between soaks since ozone reacts with chlorine increasing daily chlorine demand (in between soaks) to over 50% FC loss per day.