diff --git a/src/main/java/biomesoplenty/api/block/BlockQueries.java b/src/main/java/biomesoplenty/api/block/BlockQueries.java
index ce8da46ab..3c370a624 100644
--- a/src/main/java/biomesoplenty/api/block/BlockQueries.java
+++ b/src/main/java/biomesoplenty/api/block/BlockQueries.java
@@ -18,6 +18,7 @@ public class BlockQueries
     public static IBlockPosQuery hasWater;
     public static IBlockPosQuery airAbove;
     public static IBlockPosQuery airBelow;
+    public static IBlockPosQuery waterCovered;
     public static IBlockPosQuery breakable;
     public static IBlockPosQuery air;
     public static IBlockPosQuery airOrLeaves;
@@ -43,5 +44,4 @@ public class BlockQueries
     public static IBlockPosQuery underwater;
     public static IBlockPosQuery suitableForReed;
     public static IBlockPosQuery rootsCanDigThrough;
-    
 }
\ No newline at end of file
diff --git a/src/main/java/biomesoplenty/common/biome/overworld/BiomeGenCoralReef.java b/src/main/java/biomesoplenty/common/biome/overworld/BiomeGenCoralReef.java
index 8865dba13..7663e0698 100644
--- a/src/main/java/biomesoplenty/common/biome/overworld/BiomeGenCoralReef.java
+++ b/src/main/java/biomesoplenty/common/biome/overworld/BiomeGenCoralReef.java
@@ -8,29 +8,18 @@
 
 package biomesoplenty.common.biome.overworld;
 
-import net.minecraft.block.BlockTallGrass;
-import net.minecraft.init.Blocks;
-import net.minecraft.util.BlockPos;
-import net.minecraft.world.biome.BiomeGenBase.SpawnListEntry;
 import biomesoplenty.api.biome.BOPBiome;
 import biomesoplenty.api.biome.generation.GeneratorStage;
-import biomesoplenty.api.biome.generation.GeneratorWeighted;
 import biomesoplenty.api.block.BOPBlocks;
+import biomesoplenty.api.block.BlockQueries;
 import biomesoplenty.common.block.BlockBOPCoral;
-import biomesoplenty.common.entities.EntityButterfly;
-import biomesoplenty.common.enums.BOPClimates;
-import biomesoplenty.common.enums.BOPFlowers;
 import biomesoplenty.common.enums.BOPGems;
-import biomesoplenty.common.enums.BOPPlants;
-import biomesoplenty.common.enums.BOPTrees;
-import biomesoplenty.common.enums.BOPWoods;
 import biomesoplenty.common.util.biome.GeneratorUtils.ScatterYMethod;
 import biomesoplenty.common.world.BOPWorldSettings;
+import biomesoplenty.common.world.feature.GeneratorColumns;
 import biomesoplenty.common.world.feature.GeneratorFlora;
-import biomesoplenty.common.world.feature.GeneratorGrass;
 import biomesoplenty.common.world.feature.GeneratorOreSingle;
-import biomesoplenty.common.world.feature.tree.GeneratorBasicTree;
-import biomesoplenty.common.world.feature.tree.GeneratorBigTree;
+import net.minecraft.init.Blocks;
  
 public class BiomeGenCoralReef extends BOPBiome
 {
@@ -54,6 +43,9 @@ public class BiomeGenCoralReef extends BOPBiome
         this.addGenerator("glowing_coral", GeneratorStage.LILYPAD, (new GeneratorFlora.Builder()).amountPerChunk(15.0F).replace(Blocks.water).with(BOPBlocks.coral.getDefaultState().withProperty(BlockBOPCoral.VARIANT, BlockBOPCoral.CoralType.GLOWING)).scatterYMethod(ScatterYMethod.AT_GROUND).create());
         this.addGenerator("algae", GeneratorStage.LILYPAD, (new GeneratorFlora.Builder()).amountPerChunk(3.0F).replace(Blocks.water).with(BOPBlocks.coral.getDefaultState().withProperty(BlockBOPCoral.VARIANT, BlockBOPCoral.CoralType.ALGAE)).scatterYMethod(ScatterYMethod.AT_GROUND).create());
          
+        // kelp
+        this.addGenerator("kelp", GeneratorStage.LILYPAD, (new GeneratorColumns.Builder()).replace(BlockQueries.waterCovered).placeOn(BlockQueries.groundBlocks).with(BOPBlocks.seaweed.getDefaultState()).scatterYMethod(ScatterYMethod.AT_GROUND).create());
+        
         // gem
         this.addGenerator("sapphire", GeneratorStage.SAND, (new GeneratorOreSingle.Builder()).amountPerChunk(12).with(BOPGems.SAPPHIRE).create()); 
     }
diff --git a/src/main/java/biomesoplenty/common/init/ModBlockQueries.java b/src/main/java/biomesoplenty/common/init/ModBlockQueries.java
index 7ad19cb8f..c77e9ed71 100644
--- a/src/main/java/biomesoplenty/common/init/ModBlockQueries.java
+++ b/src/main/java/biomesoplenty/common/init/ModBlockQueries.java
@@ -61,6 +61,16 @@ public class ModBlockQueries
             }
         };
         
+        // Match block positions with water above
+        waterCovered = new IBlockPosQuery()
+        {
+            @Override
+            public boolean matches(World world, BlockPos pos)
+            {
+                return world.getBlockState(pos).getBlock().getMaterial() == Material.water && world.getBlockState(pos.up()).getBlock().getMaterial() == Material.water;
+            }
+        };
+        
         // Match blocks which are not unbreakable - IE not bedrock, barrier, command blocks
         breakable = new IBlockPosQuery()
         {
diff --git a/src/main/java/biomesoplenty/common/world/feature/GeneratorColumns.java b/src/main/java/biomesoplenty/common/world/feature/GeneratorColumns.java
index d9b317f08..09b39c928 100644
--- a/src/main/java/biomesoplenty/common/world/feature/GeneratorColumns.java
+++ b/src/main/java/biomesoplenty/common/world/feature/GeneratorColumns.java
@@ -75,17 +75,16 @@ public class GeneratorColumns extends GeneratorReplacing
             BlockPos genPos = pos.add(rand.nextInt(4) - rand.nextInt(4), rand.nextInt(3) - rand.nextInt(3), rand.nextInt(4) - rand.nextInt(4));
                 
             // see if we can place the column
-            if (this.placeOn.matches(world, genPos.down()))
+            if (this.placeOn.matches(world, genPos.down()) && this.replace.matches(world, genPos))
             {
                 // choose random target height
-                int height = GeneratorUtils.nextIntBetween(rand, this.minHeight, this.maxHeight);
+                int targetHeight = GeneratorUtils.nextIntBetween(rand, this.minHeight, this.maxHeight);
                 
                 // keep placing blocks upwards (if there's room)
-                while(height > 0 && world.isAirBlock(genPos))
+                for (int height = targetHeight; height >= 0 && replace.matches(world, genPos); height--)
                 {
                     world.setBlockState(genPos, this.with);
                     genPos = genPos.up();
-                    height--;
                 }
             }
         }
diff --git a/src/main/java/biomesoplenty/common/world/feature/tree/GeneratorTreeBase.java b/src/main/java/biomesoplenty/common/world/feature/tree/GeneratorTreeBase.java
index b3c261706..8c90f14e8 100644
--- a/src/main/java/biomesoplenty/common/world/feature/tree/GeneratorTreeBase.java
+++ b/src/main/java/biomesoplenty/common/world/feature/tree/GeneratorTreeBase.java
@@ -113,26 +113,12 @@ public abstract class GeneratorTreeBase extends BOPGeneratorBase
         }
         public T vine(IBlockState a)
         {
-            if (a == null)
-            {
-                this.vine = null;
-            }
-            else
-            {
-                this.vine = a;
-            }
+            this.vine = a;
             return this.self();
         }
         public T hanging(IBlockState a)
         {
-            if (a == null)
-            {
-                this.hanging = null;
-            }
-            else
-            {
-                this.hanging = a;
-            }
+            this.hanging = a;
             return this.self();
         }