Setup alerting for telegraf ping plugin

i install influxdb, telegraf and grafana
i enabled ping plugin in telegraf to ping few servers on my network every 1sec
I would like to be able to send alert if host is not replying for more than 2sec
i tried few things and i cannot go lower than 10-15sec
i setup notification to be send slack group and because my network converged in less than 4sec i am not getting alerts
graph shows gap during time of outage
can somebody help me with alerting part - there is not a lot of info how it works.

Thank you