How Often to Drain and Refill?

[benalbert]

Hi All,

I recently joined the ranks of hot tub owners back in July.  Since then I've heard many different opinions on how often you should drain and refill a hot tub ranging from 3 months, 4 months, 6 months, annually and even "whenever the water looks/smells gross and you can't fix it with chemicals".  So what is the correct frequency for completely draining and refilling a hot tub?

Some more info specific to my hot tub:

• I have a ThermoSpas hot tub that I installed in July, it's 550 gallons
• My hot tub has an Ozonator and uses chlorine as the sanitizer
• Mostly my wife and I use the hot tub, about 3-4 times per week
• After every use I add the non-chlorine sanitizer as prescribed by the manufacturer (Potassium Peroxmonosulfate)
• I'm very diligent about testing and adding chemicals (adding small amounts of chlorine about every other day)
• Once per week I add Leisure Time Bright and Clear and Spa Defender (de-scaler).  The latter a fella at Leslie's Pool supply said was the most important part of hot tub maintenance to avoid scaling from building up on pipes and pumps
• Ph, alkalinity and water hardness levels are within proper levels
• I clean the filters once per week
• I have a separate set of filters that I've already swapped out and let the original filters soak overnight in a filter cleaning solution

My water is perfectly clear, doesn't foam up at all and has no smell to it.  So again, how often should I drain and refill my tub?  Three to four times per year seems a bit wasteful to me, especially if the water looks, smells and chemically tests fine.  But I also don't want to cause my hot tub long term damage by not refreshing the water.

What does everyone else on this forum do, and can you back it up with references or science?    Thanks in advance!

[arobbert]

You can tell when to refill if you have persistent high levels of combined chloramines. You test for this with a drop test kit (not strips, they are inaccurate). If the number is much above 1 (1.5, 2 or more) you can try shocking to bring it down to 1 or less. It will help if you maintain proper sanitization/oxidation practices. There are chloramines and other disolved solids aka bather waste that can't be oxidized. Eventually they will build to a level that can't be managed by normal sanitation/oxidation processes or shocking. The water will require more chlorine or bromine and will be difficult to maintain.  This is a good time to drain and refill. The amount of time for this to happen varies and is affected by spa size, number of bathers, sanitizer/oxidizer application and frequency of use. For most users this is 3 to 4 months. There are many users getting 6 or months out a fill. You can also tell if you have persistent cloudy water that requires constant shocking. If you get to this stage you've gone to far. The CC test is a way to tell by testing and can indicate unseen problems. It will also indicate overall health of the water.

[benalbert]

Thanks sir, much appreciated!  

Any particular drop kit, or will any of the ones sold online work?

 

[arobbert]

This one

https://www.amazon.com/dp/B004BGF7TI/ref=asc_df_B004BGF7TI5337605/?tag=hyprod-20&creative=394997&creativeASIN=B004BGF7TI&linkCode=df0&hvadid=198092864586&hvpos=1o2&hvnetw=g&hvrand=532667794853555589&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9017486&hvtargid=pla-553423955032

Or this one that has more tests

http://tftestkits.net/TF-100-Test-Kit-p4.html

[benalbert]

Cool, I will definitely pick one of these up.  Thanks again! 

[arobbert]

You're welcome let us know how it goes!