diff --git a/_data/rules.yml b/_data/rules.yml
index 255b5fb..6f5d04d 100644
--- a/_data/rules.yml
+++ b/_data/rules.yml
@@ -1539,7 +1539,7 @@ groups:
                 for: 3m
               - name: Nats high memory usage
                 description: NATS server memory usage is above 200MB for {{ $labels.instance }}
-                query: "gnatsd_varz_mem > 200000000"
+                query: "gnatsd_varz_mem > 200 * 1024 * 1024"
                 severity: warning
                 for: 5m
               - name: Nats slow consumers
@@ -1549,7 +1549,7 @@ groups:
                 for: 3m
               - name: Nats server down
                 description: NATS server has been down for more than 5 minutes
-                query: "absent(gnatsd_connz_total)"
+                query: "absent(up{job="nats"})"
                 severity: critical
                 for: 5m
               - name: Nats high CPU usage
@@ -1577,8 +1577,8 @@ groups:
                 query: "gnatsd_connz_subscriptions > 1000"
                 severity: warning
                 for: 5m
-              - name: Nats high pending messages
-                description: NATS server has more than 100,000 pending messages
+              - name: Nats high pending bytes
+                description: NATS server has more than 100,000 pending bytes
                 query: "gnatsd_connz_pending_bytes > 100000"
                 severity: warning
                 for: 5m
@@ -1598,8 +1598,8 @@ groups:
                 severity: warning
                 for: 5m
               - name: Nats max payload size exceeded
-                description: The max payload size allowed by NATS has been exceeded
-                query: "max(gnatsd_varz_max_payload) > 1000000"
+                description: The max payload size allowed by NATS has been exceeded (1MB)
+                query: "max(gnatsd_varz_max_payload) > 1024 * 1024"
                 severity: critical
                 for: 5m
               - name: Nats leaf node connection issue