New hot tub owner struggling with Chlorine levels in hot tub with UV and Ozone generator

[blindpanic]

I’m a new hot tub owner and I'm struggling with maintaining my spa levels. I've lots of questions!

The spa
I've recently purchased with a combined spa (1,500L/400 gallons) and plunge pool (6,000L/1600 gallons). We only heat the spa end to around 38 Celsius (100 Fahrenheit). The pool end is left to ambient temperature which is around 31 Celsius (88 farenheit) in the Australian summer.

Current maintenance routine
My spa has an Ozone generator and a UV system in it. I’m currently following manufacturer’s recommendations and using dichlor as the sanitizer at a fixed rate of around 6g to 10g per 1000L daily. I put MPS in the pool end weekly as it retains chlorine. Obviously this makes the CYA levels go up quickly

I’m having the following problems with it:
• The sanitizer level in the spa goes to zero (both FC and CC) in a couple of hours after adding it. I suspect that the UV light and the spa temp is removing the sanitizer. I’ve purged the spa with pipe cleaner which, I believe discounts biofilm in the pipes consuming the chlorine
• I can keep going treating the spa in the way the manufacturer recommends but this will likely get the CYA levels high needing regular spa draining which I’ve already had to do after 2-3 months ownership. The pool is over due for a water change due to high CYA levels.

Questions:
• I’m looking to a keep a low(er) maintenance routine. Should I move to a bromine sanitizer as it will tolerate the high temps? The manufacturer recommends against doing this. They’ve not much guidance apart from they have seen people over sanitize their spas with Bromine.
• Otherwise the dichlor bleach method may work well but I’m concerned around damaging the spa which invalidate the warranty. How can I diagnose if I’m damaging the tub?
• I believe the Ozone and UV systems are really for oxidization and I still need to keep the chlorine levels within recommended ranges. Is this right? Is there any need for me to add MPS or chlorine shock to the water especially of there is no combined chlorine?

Thanks for making it this far into my question. Hopefully this all makes sense!

 

[Mdragger88]

Liquid chlorine will not damage your tub anymore than dichlor - just be sure to not pour it on the shell. Pour it slowly infront of a running return.
Mps can be irritating, it reads as cc’s when testing if the special interference reagent isn’t used (which really confuses things) & it adds sulfates to the water which can build up and damage your heaters. It’s effects are also not listed in
PoolMath.
For all these reasons I personally have never used it.
Mps is an oxidizer only.
Chlorine is both an oxidizer and a sanitizer so why use something else.
Keep it simple
The ozone & uv will oxidize fc once bather waste has been oxidized. If possible you can set it to operate just after use & then go off so that it doesn’t constantly consume your standby fc. Not all systems can do this.
Ozone can be helpful for frequently used tubs but can become bothersome for infrequently used ones.
Understanding how they work is essential to making them work for you instead of against you.
Fwiw- Many people don’t elect to replace their uv when it goes out & notice no difference.

Ozone Systems - Further Reading

www.troublefreepool.com

UV Systems - Further Reading

www.troublefreepool.com

Putting in sanitizer at a fixed rate on an arbitrary schedule is a recipe for problems.
You must feed the tub what it needs when it needs it while also accounting for the bather load & standby needs, while always keeping fc above minimum for your cya.
That sounds hard to figure out but it really isn’t. Most people just aren’t using enough chlorine. Your frequent testing, before & after use, must be your guide.
Once cya gets above 50 ppm it gets very hard to keep the tub sanitary.


If you don’t already have one you need a proper test kit - in Australia we recommend the clear choice labs one

Pool Test Kits - Further Reading

www.troublefreepool.com

Then follow the chlorine spa guide

How do I use Chlorine in my Spa (or pool)?

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