I have a small external alarm unit that I bought off Etsy (link) with below code in use. Unsure how you actually make the Apex base unit make an audible alarm though..
Set OFF
Fallback ON
If LEAK_1 CLOSED Then ON
If LEAK_2 CLOSED Then ON
If LEAK_3 CLOSED Then ON
If LEAK_4 CLOSED Then ON
If LEAK_5 CLOSED Then ON
If Tmp > 27.0 Then ON
If pH > 8.50 Then ON
If ORP > 440 Then ON
If Output RETURN_PUMP = OFF Then ON
If Output SKIMMER Watts < 1 Then ON
If ATO_HI CLOSED Then ON
If RO_HI CLOSED Then ON
If RO_HH CLOSED Then ON
If Error ATK_PMUP Then ON
If SUMP > 24.0 Then ON
If ALK > 11.00 Then ON
If RO_LVL < 35.0 Then ON
Defer 010:00 Then OFF