Cyanuric acid problem using dichlor - what's the best option for unstable chlorine?


May 17, 2020
New Hampshire
Hello all, I didn't realize dichlor had cyanuric acid and was confused as to why my levels were so high in the spa (doh!). I have been reading a lot of blogs on this topic and getting confused. I want to try the method of starting out with dichlor and then switching to unstable chlorine once the levels of cyanuric acid are good. But getting confused.

The set up:
  • We have a 450 gallon spa with ozonator.
  • I also use LEISURE TIME SGQ-02 Spas Hot Tub Enzyme once a week
  • We have been putting in 1/2 oz of dichlor granules after every use, keeping the chlorine levels low (because of the ozonator and enzymes) between 1-3. In general I am in favor of anything that lets us keep the chlorine level low.
  • I use it about 5 days a week, solo. Occasionally we might have as many have 5 or 6 kids and grownups in and out of it all day.
  • The spa is my baby. While I don't want to overpay or spend a fortune I'm open to the best solution even if it's a bit costlier
The questions:
  • What is the best unstable chlorine to use once the cyanuric acid levels are right? Calcium Hypochlorite? Sodium Hypochlorite? Clorox bleach? [email protected]? Something else?
  • Can I get a sleeve of pool shock and use that? (not the whole thing, obviously, but a little at a time)
  • Can I literally buy a bottle of Clorox and use that? Or should I be getting a bottle of liquid pool chlorine? If so, do you pour it in or spray it over the top?
  • What would be the right frequency and dosage?
  • Do I need to keep an eye on anything else with the chemistry if I switch from dichlor?
Thanks so much!

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Once your CYA has elevated to a proper level, liquid chlorine (or regular bleach) is the best - no side effects. Easy to dose, pour, and mixes well. Doesn't impact any other chemical levels. Be sure you are testing your water with a TF-100 or Taylor K-2006C test kit though. Accuracy is everything. The link below is a great resource if you haven't seen it already.

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


Bronze Supporter
Jun 1, 2018
Hernando, Ms
Also regardless of ozone or enzymes you should maintain a proper fc level based on the FC/CYA Chart lest you will have an unsanitary body of water. You never wanna get to zero or nasty transmissible stuff will grow quickly. PoolMath will help u with dosing calculations. Dichlor is also acidic & will tank your ph quickly leading to irritation as well as heater corrosion so be mindful of ph. Liquid chlorine doesn’t have this effect. Just pour it in front of a running jet. Unadulterated household bleach (non splashless, unscented, without fabric conditioners/ cloromax) is getting hard to find so your best bet is the pool versions @ walmart & hardware stores etc. Many here including myself use a drop in saltwater chlorine generator to do most of the heavy lifting and just occasionally supplement with liquid chlorine as needed for heavy bather loads.
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