I cannnot get any FC reading???

Have 18 x 36 inground vinyl lined pool approx 27000 gallons . Have been doing this for 25 years and am really puzzled at this situation. Open pool 2 weeks ago, as usual vacuum most of algae and dirt to waste. Let pump run continiously 24/7. Added 12 gals Clorox directly to skimmer. This usually clears pool in about 2 days. Checked
readings. Have FC of 1.5, TC of over 10, PH 7. TA 80, CYA 30. Now after 2 weeks pool is cloudy and will not clear. Last night I
have added another 5 gallons of Clorox and this morning the FC reading very low around 1. and also the TC reading is down
to 1. and also notice a PH going to about 6.8. I just bought the Clorox from store so I would not think it is bad. I
have used 2 different test kits using new reagents. Unless the bleach is bad I can't understand why the FC reading will not get higher. Thanks.

If your CYA level dropped over the winter, then if the FC had gotten to zero then soil bacteria in the pool could have converted some CYA into ammonia. That creates a huge chlorine demand upon opening and initially the added chlorine creates CC which is what you have been seeing. Keep adding chlorine until it starts to hold. It may take a lot. You can do a bucket test if you want to figure out roughly how much it will take where 1/4 teaspoon of 6% bleach in 2 gallons is 10 ppm FC. Technical details of what happens is in this post while my own personal experience with this is in described in this thread with a summary in this post.

The FC is getting used up killing algae and oxidizing your CC- at your CYA level, need to maintain about 3-6ppm FC, so keep adding bleach to get it up there. with the water still cloudy I'd go to shock levels- I think 15 for CYA 30, and maintain til <1 loss FC overnight, and <.5 CC- then let FC lower to the 3-6 range for maintainance...

Are you testing your pH while your chlorine is low? (High chlorine readings will give you inaccurate pH readings.) If so, you need to add some 20 Mule Team Borax to bump your pH up a bit.