Hot tub will not hold chlorine, even after plumbing flush

[marleecj]

I need help! I've stumped multiple hot tub "experts" with this problem and am driving myself crazy!

My hot tub will not hold chlorine, no matter what I do. After putting in the proper amount of chlorine and getting a proper reading (between 3-5ppm free chlorine), within one hour, the reading is back down to zero (for both free chlorine and total chlorine).

Here are details on my levels, equipment and usage:

• Hot tub is always covered except when in use. (outdoor tub)
• I regularly use shock, typically right after every use. I've tried both chlorine and non-chlorine shock.
• Only 2 people (me and my husband) regularly use the hot tub, about 2 times a week. No children have ever been in the hot tub.
• Alkalinity and pH levels are in range. (Alkalinity: 85 ppm, pH: 7.4 ppm)
• My cyanuric acid level is in range. (94 ppm)
• Total hardness is in range. (200 ppm)
• Metal levels are in range. (0 ppm)
• I've tested these levels myself using test strips AND at two different pool/spa stores that provide water analysis.

Here's what I've already tried:

• I have done TWO spa flushes and drains with Oh Yuk Hot Tub Cleaner. I followed all the instructions and even let it sit overnight for the "stubborn contaminants" treatment found on Oh Yuk's website. After draining, I also thoroughly cleaned the shell and the cover. I also thoroughly cleaned my filter by soaking in LeisureTime Filter Clean and spraying off with a hose.
• After draining and flushing with Oh Yuk, I attempted to switch to bromine, hoping to have better results. I had the same issue. I followed instructions exactly for bromine too. Used shock and sodium bromide to activate the bromine. Bromine levels still would be down to zero within an hour.
• I did another drain and flush before switching back to chlorine.
• I have tried to superchlorinate by bringing chlorine level to approximately 100pm. The levels still drop extremely quickly. With an initial reading of over 10ppm (the highest test strips go), the levels were back down to 0 within three hours.
• Attempted to use a phosphate remover, but the level actually went higher after using the remover. I've been told by spa dealers that phosphates don't really affect water chemistry though because they are so small (parts per billion!).

Hot tub details:

• 250 gallons
• Water's Edge Spa, LeCirc
• Sanitizer: Chlorine, LeisureTime Spa 56. I follow LeisureTime's instructions for the proper amount, which equals 1 tsp for a 250 gallon tub. But I've also tried using more as recommended by my hot tub dealer (approximately 3 tablespoons) but it still disappears within a couple of hours.
• Typical temperature: 103 F
• Purchased brand new less than one year ago (July 2020)

Does anyone have ANY ideas?! Any help would be greatly appreciated.

[Tman122]

You want the chlorine to kill the nasties and then be gone.

[marleecj]

You want the chlorine to kill the nasties and then be gone.

Thanks for your response!

Are you saying that my chlorine level should usually be zero?

I'm just not sure if it's killing what it's supposed to. My water is consistently cloudy.

[cranbiz]

Hardness is a bit on the high side but still within acceptable limits, TA could be good, could be on the low side, some say 50-85 ppm and some say 120-150 ppm. Phosphates do cause issues, have your water tested for them.

Do you have Ozone?

I'm not sure how well Oh Yuk works, I use Ahhsome, which I know works well.

[Tman122]

You want the chlorine to kill the nasties and then be gone.

Thanks for your response!

Are you saying that my chlorine level should usually be zero?

I'm just not sure if it's killing what it's supposed to. My water is consistently cloudy.

I used to achieve a chlorine level of 5-10 ppm 15 minutes after adding. This is enough to kill the nasties. Then the next day/soak it was less than 1. Chlorinated city drinking water has a chlorine PPM of .5 or less.