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The method is described in the sticky
How do I use Chlorine in my Spa. Note, however, that unless you are using the spa regularly every day or two, then the method may be more work than you are willing to do compared to bromine tabs in a floating feeder. The reason is that you need to maintain a chlorine level in between soaks.
Also, the method requires some work after a fresh fill to get the water in balance, but after that it should last at least twice as long between water changes compared to Dichlor-only or bromine. It will certainly be the least expensive method because bleach is not expensive.
The method starts out using Dichlor until the Cyanuric Acid (CYA) builds up to around 30-40 ppm (after cumulatively adding around 33-44 ppm FC over time). You then switch to using bleach (except once a month one day of Dichlor use). In order to prevent the pH from rising from carbon dioxide outgassing, the Total Alkalinity (TA) is lowered to around 50 ppm and 50 ppm borates are added (usually from boric acid) for additional pH buffering. After that it's just adding bleach after each soak in proportion to the bather load and adding more chlorine in between soaks if one isn't soaking regularly.
So it's not a trivial method, especially at first, but it results in the best water quality.
Before you do your next refill to start the method, I strongly suggest you use
Ahh-Some in the spa as it will get rid of any biofilms or greases that may be present so that you start with a clean slate. Even new spas can have such problems.