Hello, I will only discuss the redox chemistry of the reaction, maybe the reaction needs reviewing.
Cl+ + 2e- ---> Cl-
Cl- ---> Cl5+ + 6e-
3ClO- + Cl- ---> 3Cl- + ClO3-
We may even simplify it by subtracting the chlorine on the left:
3ClO- ---> 2Cl- + ClO3-
So, you should check the concentration of bleach; as you see in the redox reaction, three moles of bleach is needed to produce one mole of chlorate. Also, brown precipitates don't seem normal, please check the purity of your substances. Use distilled water as much as possible. If there are particles in your starting solutions, don't let them interfere with your business, just filter them off.
I haven't checked your concentrations, since we use SI units in Turkey, I am not familiar with gallons, etc.