diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/BloomFilterDuplicateRemover.java b/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/BloomFilterDuplicateRemover.java
index 34d6f7c..1c89e5c 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/BloomFilterDuplicateRemover.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/BloomFilterDuplicateRemover.java
@@ -23,9 +23,14 @@ public class BloomFilterDuplicateRemover implements DuplicateRemover {
     private AtomicInteger counter;
 
     public BloomFilterDuplicateRemover(int expectedInsertions) {
-        this(expectedInsertions, 0.03);
+        this(expectedInsertions, 0.01);
     }
 
+    /**
+     *
+     * @param expectedInsertions the number of expected insertions to the constructed
+     * @param fpp the desired false positive probability (must be positive and less than 1.0)
+     */
     public BloomFilterDuplicateRemover(int expectedInsertions, double fpp) {
         this.expectedInsertions = expectedInsertions;
         this.fpp = fpp;
diff --git a/webmagic-core/src/test/java/us/codecraft/webmagic/scheduler/BloomFilterDuplicateRemoverTest.java b/webmagic-core/src/test/java/us/codecraft/webmagic/scheduler/BloomFilterDuplicateRemoverTest.java
index a82d74e..f8e0b9a 100644
--- a/webmagic-core/src/test/java/us/codecraft/webmagic/scheduler/BloomFilterDuplicateRemoverTest.java
+++ b/webmagic-core/src/test/java/us/codecraft/webmagic/scheduler/BloomFilterDuplicateRemoverTest.java
@@ -1,8 +1,11 @@
 package us.codecraft.webmagic.scheduler;
 
+import org.junit.Ignore;
 import org.junit.Test;
 import us.codecraft.webmagic.Request;
 import us.codecraft.webmagic.scheduler.component.BloomFilterDuplicateRemover;
+import us.codecraft.webmagic.scheduler.component.DuplicateRemover;
+import us.codecraft.webmagic.scheduler.component.HashSetDuplicateRemover;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -24,4 +27,54 @@ public class BloomFilterDuplicateRemoverTest {
         assertThat(isDuplicate).isTrue();
 
     }
+
+    @Ignore("long time")
+    @Test
+    public void testMemory() throws Exception {
+        int times = 5000000;
+        DuplicateRemover duplicateRemover = new BloomFilterDuplicateRemover(times,0.005);
+        long freeMemory = Runtime.getRuntime().freeMemory();
+        long time = System.currentTimeMillis();
+        for (int i = 0; i < times; i++) {
+            duplicateRemover.isDuplicate(new Request(String.valueOf(i)), null);
+        }
+        System.out.println("Time used by bloomfilter:" + (System.currentTimeMillis() - time));
+        System.out.println("Memory used by bloomfilter:" + (freeMemory - Runtime.getRuntime().freeMemory()));
+
+        duplicateRemover = new HashSetDuplicateRemover();
+        System.gc();
+        freeMemory = Runtime.getRuntime().freeMemory();
+        time = System.currentTimeMillis();
+        for (int i = 0; i < times; i++) {
+            duplicateRemover.isDuplicate(new Request(String.valueOf(i)), null);
+        }
+        System.out.println("Time used by hashset:" + (System.currentTimeMillis() - time));
+        System.out.println("Memory used by hashset:" + (freeMemory - Runtime.getRuntime().freeMemory()));
+    }
+
+    @Ignore("long time")
+    @Test
+    public void testMissHit() throws Exception {
+        int times = 5000000;
+        DuplicateRemover duplicateRemover = new BloomFilterDuplicateRemover(times, 0.01);
+        int right = 0;
+        int wrong = 0;
+        int missCheck = 0;
+        for (int i = 0; i < times; i++) {
+            boolean duplicate = duplicateRemover.isDuplicate(new Request(String.valueOf(i)), null);
+            if (duplicate) {
+                wrong++;
+            } else {
+                right++;
+            }
+            duplicate = duplicateRemover.isDuplicate(new Request(String.valueOf(i)), null);
+            if (!duplicate) {
+                missCheck++;
+            }
+        }
+
+        System.out.println("Right count: " + right + " Wrong count: " + wrong + " Miss check: " + missCheck);
+    }
+
+
 }