diff --git a/Master-Server-API.md b/Master-Server-API.md
index 5399b3c..df122f4 100644
--- a/Master-Server-API.md
+++ b/Master-Server-API.md
@@ -66,6 +66,8 @@ curl "http://localhost:9333/dir/lookup?volumeId=3&collection=turbo"
 
 If your system has many deletions, the deleted file's disk space will not be synchronously re-claimed. There is a background job to check volume disk usage. If empty space is more than the threshold, default to 0.3 which is 30%, the vacuum job will make the volume readonly, create a new volume with only existing files, and switch on the new volume. If you are impatient or doing some testing, vacuum the unused spaces this way.
 
+Currently the garbage collection is hard coded in master to run every 15 minutes. 
+
 ```bash
 curl "http://localhost:9333/vol/vacuum"
 curl "http://localhost:9333/vol/vacuum?garbageThreshold=0.4"