diff --git a/CHANGELOG.asciidoc b/CHANGELOG.asciidoc
index a7f9f1b2c69d..174eec9abf70 100644
--- a/CHANGELOG.asciidoc
+++ b/CHANGELOG.asciidoc
@@ -264,8 +264,10 @@ https://github.com/elastic/beats/compare/v6.0.0-beta2...master[Check the HEAD di
 - Add experimental module to collect metrics from munin nodes. {pull}6517[6517]
 - Add support for wildcards and explicit metrics grouping in jolokia/jmx. {pull}6462[6462]
 - Set `collector` as default metricset in Prometheus module. {pull}6636[6636]
+- Set `mntr` as default metricset in Zookeeper module. {pull}6674[6674]
 - Set default metricsets in vSphere module. {pull}6676[6676]
-- Set `status` as default metricset in Apache module. {pull}[]
+- Set `status` as default metricset in Apache module. {pull}6673[6673]
+- Set `namespace` as default metricset in Aerospike module. {pull}6669[6669]
 
 *Packetbeat*
 
diff --git a/metricbeat/docs/modules/aerospike.asciidoc b/metricbeat/docs/modules/aerospike.asciidoc
index a1fde6987db4..c25c33db964b 100644
--- a/metricbeat/docs/modules/aerospike.asciidoc
+++ b/metricbeat/docs/modules/aerospike.asciidoc
@@ -7,7 +7,7 @@ This file is generated! See scripts/docs_collector.py
 
 beta[]
 
-The Aerospike module uses the http://www.aerospike.com/docs/reference/info[Info command] to collect metrics.
+The Aerospike module uses the http://www.aerospike.com/docs/reference/info[Info command] to collect metrics. The default metricset is `namespace`.
 
 [float]
 === Compatibility
@@ -25,9 +25,6 @@ in <<configuration-metricbeat>>. Here is an example configuration:
 ----
 metricbeat.modules:
 - module: aerospike
-  metricsets: ["namespace"]
-  enabled: false
-  period: 10s
   hosts: ["localhost:3000"]
 ----
 
diff --git a/metricbeat/docs/modules/zookeeper.asciidoc b/metricbeat/docs/modules/zookeeper.asciidoc
index 3f0e63174a34..bc3fc877bdfb 100644
--- a/metricbeat/docs/modules/zookeeper.asciidoc
+++ b/metricbeat/docs/modules/zookeeper.asciidoc
@@ -5,7 +5,8 @@ This file is generated! See scripts/docs_collector.py
 [[metricbeat-module-zookeeper]]
 == ZooKeeper module
 
-The ZooKeeper module fetches statistics from the ZooKeeper service.
+The ZooKeeper module fetches statistics from the ZooKeeper service. The default
+metricset is `mntr`.
 
 [float]
 === Compatibility
@@ -24,7 +25,6 @@ in <<configuration-metricbeat>>. Here is an example configuration:
 ----
 metricbeat.modules:
 - module: zookeeper
-  metricsets: ["mntr"]
   period: 10s
   hosts: ["localhost:2181"]
 ----
diff --git a/metricbeat/metricbeat.reference.yml b/metricbeat/metricbeat.reference.yml
index 8553507c9df2..8422354127d9 100644
--- a/metricbeat/metricbeat.reference.yml
+++ b/metricbeat/metricbeat.reference.yml
@@ -117,7 +117,7 @@ metricbeat.modules:
 #------------------------------ Aerospike Module -----------------------------
 - module: aerospike
   metricsets: ["namespace"]
-  enabled: false
+  enabled: true
   period: 10s
   hosts: ["localhost:3000"]
 
@@ -502,6 +502,7 @@ metricbeat.modules:
 
 #------------------------------ ZooKeeper Module -----------------------------
 - module: zookeeper
+  enabled: true
   metricsets: ["mntr"]
   period: 10s
   hosts: ["localhost:2181"]
diff --git a/metricbeat/module/aerospike/_meta/config.reference.yml b/metricbeat/module/aerospike/_meta/config.reference.yml
new file mode 100644
index 000000000000..38aca68f9514
--- /dev/null
+++ b/metricbeat/module/aerospike/_meta/config.reference.yml
@@ -0,0 +1,5 @@
+- module: aerospike
+  metricsets: ["namespace"]
+  enabled: true
+  period: 10s
+  hosts: ["localhost:3000"]
diff --git a/metricbeat/module/aerospike/_meta/config.yml b/metricbeat/module/aerospike/_meta/config.yml
index 787e314dc60d..0a4a883f4749 100644
--- a/metricbeat/module/aerospike/_meta/config.yml
+++ b/metricbeat/module/aerospike/_meta/config.yml
@@ -1,5 +1,2 @@
 - module: aerospike
-  metricsets: ["namespace"]
-  enabled: false
-  period: 10s
   hosts: ["localhost:3000"]
diff --git a/metricbeat/module/aerospike/_meta/docs.asciidoc b/metricbeat/module/aerospike/_meta/docs.asciidoc
index 9d1f59230d34..3cbf6660edf9 100644
--- a/metricbeat/module/aerospike/_meta/docs.asciidoc
+++ b/metricbeat/module/aerospike/_meta/docs.asciidoc
@@ -1,4 +1,4 @@
-The Aerospike module uses the http://www.aerospike.com/docs/reference/info[Info command] to collect metrics.
+The Aerospike module uses the http://www.aerospike.com/docs/reference/info[Info command] to collect metrics. The default metricset is `namespace`.
 
 [float]
 === Compatibility
diff --git a/metricbeat/module/aerospike/namespace/namespace.go b/metricbeat/module/aerospike/namespace/namespace.go
index 1dafef5eae69..e36519fef1cb 100644
--- a/metricbeat/module/aerospike/namespace/namespace.go
+++ b/metricbeat/module/aerospike/namespace/namespace.go
@@ -16,9 +16,9 @@ import (
 // init registers the MetricSet with the central registry.
 // The New method will be called after the setup of the module and before starting to fetch data
 func init() {
-	if err := mb.Registry.AddMetricSet("aerospike", "namespace", New); err != nil {
-		panic(err)
-	}
+	mb.Registry.MustAddMetricSet("aerospike", "namespace", New,
+		mb.DefaultMetricSet(),
+	)
 }
 
 // MetricSet type defines all fields of the MetricSet
diff --git a/metricbeat/module/zookeeper/_meta/config.reference.yml b/metricbeat/module/zookeeper/_meta/config.reference.yml
new file mode 100644
index 000000000000..04742813c55f
--- /dev/null
+++ b/metricbeat/module/zookeeper/_meta/config.reference.yml
@@ -0,0 +1,5 @@
+- module: zookeeper
+  enabled: true
+  metricsets: ["mntr"]
+  period: 10s
+  hosts: ["localhost:2181"]
diff --git a/metricbeat/module/zookeeper/_meta/config.yml b/metricbeat/module/zookeeper/_meta/config.yml
index 63543cefdd71..fb77d08fffa9 100644
--- a/metricbeat/module/zookeeper/_meta/config.yml
+++ b/metricbeat/module/zookeeper/_meta/config.yml
@@ -1,4 +1,3 @@
 - module: zookeeper
-  metricsets: ["mntr"]
   period: 10s
   hosts: ["localhost:2181"]
diff --git a/metricbeat/module/zookeeper/_meta/docs.asciidoc b/metricbeat/module/zookeeper/_meta/docs.asciidoc
index 8675c576c480..34b3f9500102 100644
--- a/metricbeat/module/zookeeper/_meta/docs.asciidoc
+++ b/metricbeat/module/zookeeper/_meta/docs.asciidoc
@@ -1,4 +1,5 @@
-The ZooKeeper module fetches statistics from the ZooKeeper service.
+The ZooKeeper module fetches statistics from the ZooKeeper service. The default
+metricset is `mntr`.
 
 [float]
 === Compatibility
diff --git a/metricbeat/module/zookeeper/mntr/mntr.go b/metricbeat/module/zookeeper/mntr/mntr.go
index 2cc27c71ef65..396bc0f0f9b6 100644
--- a/metricbeat/module/zookeeper/mntr/mntr.go
+++ b/metricbeat/module/zookeeper/mntr/mntr.go
@@ -36,9 +36,10 @@ import (
 )
 
 func init() {
-	if err := mb.Registry.AddMetricSet("zookeeper", "mntr", New, parse.PassThruHostParser); err != nil {
-		panic(err)
-	}
+	mb.Registry.MustAddMetricSet("zookeeper", "mntr", New,
+		mb.WithHostParser(parse.PassThruHostParser),
+		mb.DefaultMetricSet(),
+	)
 }
 
 // MetricSet for fetching ZooKeeper health metrics.
diff --git a/metricbeat/modules.d/aerospike.yml.disabled b/metricbeat/modules.d/aerospike.yml.disabled
index 787e314dc60d..0a4a883f4749 100644
--- a/metricbeat/modules.d/aerospike.yml.disabled
+++ b/metricbeat/modules.d/aerospike.yml.disabled
@@ -1,5 +1,2 @@
 - module: aerospike
-  metricsets: ["namespace"]
-  enabled: false
-  period: 10s
   hosts: ["localhost:3000"]
diff --git a/metricbeat/modules.d/zookeeper.yml.disabled b/metricbeat/modules.d/zookeeper.yml.disabled
index 63543cefdd71..fb77d08fffa9 100644
--- a/metricbeat/modules.d/zookeeper.yml.disabled
+++ b/metricbeat/modules.d/zookeeper.yml.disabled
@@ -1,4 +1,3 @@
 - module: zookeeper
-  metricsets: ["mntr"]
   period: 10s
   hosts: ["localhost:2181"]