diff --git a/.github/integration-test.py b/.github/integration-test.py
index dfbf65a..7450628 100755
--- a/.github/integration-test.py
+++ b/.github/integration-test.py
@@ -29,9 +29,9 @@ def run_systemd_image(image_name, container_name, bootstrap_pip_spec):
         '--mount', 'type=bind,source=/sys/fs/cgroup,target=/sys/fs/cgroup',
         '--detach',
         '--name', container_name,
-        # This is the minimum VM size we support.
-        # If we change this, need to change all other references to this number.
-        '--memory', '1G',
+        # A bit less than 1GB to ensure TLJH runs on 1GB VMs.
+        # If this is changed all docs references to the required memory must be changed too.
+        '--memory', '900m',
     ]
 
     if bootstrap_pip_spec:
diff --git a/docs/install/amazon.rst b/docs/install/amazon.rst
index 4ee9c86..e8408dc 100644
--- a/docs/install/amazon.rst
+++ b/docs/install/amazon.rst
@@ -76,8 +76,9 @@ Let's create the server on which we can run JupyterHub.
    `Next: Configure Instance Details` in the lower right corner.
 
    Check out our guide on How To :ref:`howto/admin/resource-estimation` to help pick
-   how much Memory / CPU your server needs. You need to have at least **1GB** of
-   RAM. The smallest instance that can fit this is a **t3.small**.
+   how much Memory / CPU your server needs.
+   We recommend you use a server with at least 2GB of RAM, such as a **t3.small**.
+   However, if you need to minimise costs you can use a server with **1GB** RAM such as a **t2.micro**, but performance will be limited.
 
    You may wish to consult the listing `here <https://www.ec2instances.info/>`_
    because it shows cost per hour. The **On Demand** price is the pertinent cost.
diff --git a/tests/test_conda.py b/tests/test_conda.py
index 12dbd81..539e646 100644
--- a/tests/test_conda.py
+++ b/tests/test_conda.py
@@ -13,14 +13,14 @@ def prefix():
     """
     Provide a temporary directory with a conda environment
     """
-    miniconda_version = '4.7.10'
-    miniconda_installer_sha256 = "8a324adcc9eaf1c09e22a992bb6234d91a94146840ee6b11c114ecadafc68121"
-    installer_url = "https://repo.continuum.io/miniconda/Miniconda3-{}-Linux-x86_64.sh".format(miniconda_version)
+    mambaforge_version = '4.10.3-7'
+    installer_sha256 = "fc872522ec427fcab10167a93e802efaf251024b58cc27b084b915a9a73c4474"
+    installer_url = "https://github.com/conda-forge/miniforge/releases/download/{v}/Mambaforge-{v}-Linux-x86_64.sh".format(v=mambaforge_version)
     with tempfile.TemporaryDirectory() as tmpdir:
-        with conda.download_miniconda_installer(installer_url, miniconda_installer_sha256) as installer_path:
+        with conda.download_miniconda_installer(installer_url, installer_sha256) as installer_path:
             conda.install_miniconda(installer_path, tmpdir)
         conda.ensure_conda_packages(tmpdir, [
-            'conda==4.8.1'
+            'conda==4.10.3'
         ])
         yield tmpdir
 
diff --git a/tljh/conda.py b/tljh/conda.py
index 3fa8a87..9c8c749 100644
--- a/tljh/conda.py
+++ b/tljh/conda.py
@@ -94,7 +94,7 @@ def ensure_conda_packages(prefix, packages):
     """
     Ensure packages (from conda-forge) are installed in the conda prefix.
     """
-    conda_executable = [os.path.join(prefix, 'bin', 'python'), '-m', 'conda']
+    conda_executable = [os.path.join(prefix, 'bin', 'mamba')]
     abspath = os.path.abspath(prefix)
     # Let subprocess errors propagate
     # Explicitly do *not* capture stderr, since that's not always JSON!
diff --git a/tljh/installer.py b/tljh/installer.py
index 2a68a19..05b4ce4 100644
--- a/tljh/installer.py
+++ b/tljh/installer.py
@@ -172,24 +172,33 @@ def ensure_user_environment(user_requirements_txt_file):
 
     miniconda_old_version = '4.5.4'
     miniconda_new_version = '4.7.10'
-    miniconda_installer_sha256 = "8a324adcc9eaf1c09e22a992bb6234d91a94146840ee6b11c114ecadafc68121"
+    # Install mambaforge using an installer from
+    # https://github.com/conda-forge/miniforge/releases
+    mambaforge_new_version = '4.10.3-7'
+    installer_sha256 = "fc872522ec427fcab10167a93e802efaf251024b58cc27b084b915a9a73c4474"
+    # Then run `mamba --version` to get the conda and mamba versions
+    # Keep these in sync with tests/test_conda.py::prefix
+    mambaforge_conda_new_version = '4.10.3'
+    mambaforge_mamba_version = '0.16.0'
 
-    if conda.check_miniconda_version(USER_ENV_PREFIX, miniconda_new_version):
+    if conda.check_miniconda_version(USER_ENV_PREFIX, mambaforge_conda_new_version):
+        conda_version = '4.10.3'
+    elif conda.check_miniconda_version(USER_ENV_PREFIX, miniconda_new_version):
         conda_version = '4.8.1'
     elif conda.check_miniconda_version(USER_ENV_PREFIX, miniconda_old_version):
         conda_version = '4.5.8'
     # If no prior miniconda installation is found, we can install a newer version
     else:
         logger.info('Downloading & setting up user environment...')
-        # FIXME: allow using miniforge
-        installer_url = "https://repo.continuum.io/miniconda/Miniconda3-{}-Linux-x86_64.sh".format(miniconda_new_version)
-        with conda.download_miniconda_installer(installer_url, miniconda_installer_sha256) as installer_path:
+        installer_url = "https://github.com/conda-forge/miniforge/releases/download/{v}/Mambaforge-{v}-Linux-x86_64.sh".format(v=mambaforge_new_version)
+        with conda.download_miniconda_installer(installer_url, installer_sha256) as installer_path:
             conda.install_miniconda(installer_path, USER_ENV_PREFIX)
-        conda_version = '4.8.1'
+        conda_version = '4.10.3'
 
     conda.ensure_conda_packages(USER_ENV_PREFIX, [
         # Conda's latest version is on conda much more so than on PyPI.
-        'conda==' + conda_version
+        'conda==' + conda_version,
+        'mamba==' + mambaforge_mamba_version,
     ])
 
     conda.ensure_pip_requirements(