Your swcg is capable of producing 1.4# of chlorine per day if run at 100% /24hrs.
That equates to approximately 5.6ppm of fc /day in your pool volume if 30k gal is correct.
The average algae free pool uses 2-4ppm fc /day give or take depending upon conditions. (Uv exposure/batherload etc)
In general rain doesn’t increase fc consumption unless its a monsoon or lots of debris involved. The overcast cloudy conditions actually reduce fc consumption.
Use
PoolMath effects of adding (select swg & enter 1.4 as output) to determine your needed run time & % to account for average daily fc needs. Probably 3-4ppm.