Within last couple weeks I've notices that I can't crank FC levels (~2) to the values I had last years (4-5) . Longer and longer (up to 24hrs) SWG runs did not help either.
So here we go to troubleshot SWG output.
I think steps I took might be useful for other forum members.
1. Make sure salt levels match your SWG requirements (usually 3,200-3.400 ppm).
2. Make sure SWG lights do not show any error statuses (cold water, not enough flow, etc) and SWG has been removed, inspected and cleaned if necessary.
Do not shock pool before doing steps 3-4. Make sure chlorine level is at least 2ppm. If not, add bleach/chlorine to raise FC to 2ppm.
3. Shut the SWG off overnight and do an OCLT. Just to give you an idea, my chlorine loss was 0.8 ppm.
Note FC level.
If FC > 1ppm, proceed to step #4.
If FC is between 0 and 1, just add bleach/chlorine to raise it to 2ppm. Follow to step #4.
if FC=0, some algae might be present and it calls for SLAM process.
4. Start SWG for 12 hours, measure chlorine loss again. Mine was around 0.8. It's a clear indicator that SWG did not produce any chlorine and it is dead even with all lights showing that it works.