Sentinel CHHC-1 question (CO2)

I have been using CO2 for a little while now. My results have been about a 20-30% increase with just using a regulator with a timer. I also discovered a leak in which more co2 was being released then I realized (still good results with no issues). I had the regulator replaced and now it seems as though the plants aren't the same they normally would be at the same timeline.

So I came across a Sentinel CHHC-1 for a really good price! I got all the instructions online and set it up. But I am not exactly sure if I am doing everything correctly.

I have an 8x8x7 tent. Regulator is set as 3.

1. When I first set the Sentinel up, it read the ppm around 340. My understanding is it should be around 1500?

2. I set the max at 1450. It was not gone up higher than 600. Should I set the regulator to release more? I was under the impression that releasing too much could freeze the regulator up.

3. I know it is on a sensor where it turns off when the lights turn off. On the Sentinel itself, the CO2 light is off. But the regulator shows as though it is still releasing CO2 (ball is at 3). Is that normal?