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
Jun 22, 2014
Texas, San Antonio/Marion, South-Central Area
Pool Size
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
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
Pool Size
Salt Water Generator
SWG Type
Intex Krystal Clear
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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