oops - chlorine spa startup misfire

Nov 28, 2021
5
virginia
greetings,
new tub owner (pdc spa- 325gal). i was following the pinned thread regarding how to use chlorine in my spa for my first fill of the tub. i completed all the water balancing steps with good results. however, when i got to the sanitation instructions, i misunderstood, and added enough dichlor to get to 25ppm CYA all at once. now my total chlorine and free chlorine are off the charts, and there is a strong bleach smell from the tub. at least the CYA is perfect... :rolleyes:

is this a problem? should i use a neutralizing agent? just uncover and wait it out?
any advice is greatly appreciated. thank you.
 
Nov 28, 2021
5
virginia
Welcome to TFP! :wave: No need to try and neutralize the FC level. It will fall on its own soon enough. What exactly is that FC level, and how are you testing?
fas-dpd on the way. in the meantime i used my old pool test kit, read over 5ppm (max). plus strips, which read over 10ppm (max). same values today, but a significant improvement in the chlorine odor, no longer overwhelming. still dont want to jump in, but any chance the chlorine actually hurt anything?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,931
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The low pH from using that much dichlor at one time could do harm to the heater coil. Have you attempted to measure pH?
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,614
NY
So by your user name I thought you might be a Van Halen fan (as it’s arguably the best guitar solo ever) but a Google search learnt me that the eruption sequence is the order that teeth come in. I GET it !!! You’re ‘cutting your teeth’ on pool/spa care. Well played. :)

And Welcome to TFP !!
 
Last edited:

5tan

Active member
Jan 9, 2021
44
Canada
Pool Size
1643
Chlorine
Liquid Chlorine
Go to PoolMath enter in your volume of water at the top, all the other parameters if you have them, then go to the bottom and enter in how much dichlor you added. For example, for a 1643L/434gal hot tub, you would need to add 80g of dichlor to hit 25ppm CYA, and 80g dichlor gives you 27ppm FC. 27ppm FC is way too high, and if there are stainless steel components in your spa or rubberized headrests, they may be adversely affected. Your FC should be 10-12ppm at most, and that's for shocking after a high bather load session. Your regular standby FC should be holding at 3-6ppm.

I would definitely uncover, turn heat to max to accelerate chlorine breakdown, turn jets and aeration to max, run for several hours and add acid as needed to keep pH in the 7.2-7.6 range (as aeration will increase pH). I would also consider neutralizing the chlorine down to 10ppm using one or more of:
* Sunlight or any source of UV light (some spas have a UV system plumbed in).
* If you have an ozonator plumbed in, ozone is a powerful chlorine eliminator. Ozonators usually run during heating and/or filtration cycles, so long as no buttons have been pressed on the control pad in the past 30 minutes.
* Hydrogen peroxide, use 3% drug store peroxide, 2 ounces per 100 gallons of spa water, to lower chlorine (or bromine) level by about 10 ppm. See How to Reduce Pool or Spa Chlorine Levels and Hydrogen Peroxide is a Dechlorination Alternative | USP Technologies
* Ascorbic acid, 1 gram of ascorbic acid will neutralize 1 milligram per liter of chlorine per 100 gallons of water. See Using Vitamin C to Neutralize Chlorine in Water Systems
 
Nov 28, 2021
5
virginia
So by your user name I thought you might be a Van Halen fan (as it’s arguably the best guitar solo ever) but a Google search learnt me that the eruption sequence is the order that teeth come in. I GET it !!! You’re ‘cutting your teeth’ on pool/spa care. Well played. :)

And Welcome to TFP !!
Van Halen fan! But also a dentist :D
Thanks and nice to be here.
 
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