FC near 0 yet pool still crystal clear

[coilerman]

My pool which has a SWG that I think is on it's last legs, tests out to just a trace of free chlorine. Yet, the pool is crystal clear. It's been like this for two weeks. I shocked it about 7 days ago but the FC drops to near 0 in 48 hours. My CYA level is 40.

Other numbers:

pH: 7.8
TA: 120
CH: 325

Is my pool unsafe for swimming?

 

[Texas Splash]

You do want some chlorine to register when you swim so you know the water is being sanitized. Your say you shocked it? What did you use and for how long? Just that once? [FC/CYA][/FC/CYA]

Also note that your CYA reading of 40 is well under the TFP recommendation for a SWG pool (70). With that low of CYA, your SWG may not be able to keep-up with the FC depletion by the sun. Before you increase the CYA to 70 though, I'd do an Overnight Chlorine Loss Test to ensure you have no heavy organic load. If you confirm no algae, then increase the CYA to 70.