diff --git a/brozzler/frontier.py b/brozzler/frontier.py
index dd3ceb3..3b3c8f9 100644
--- a/brozzler/frontier.py
+++ b/brozzler/frontier.py
@@ -4,6 +4,7 @@ import random
 import time
 import datetime
 import rethinkdb
+import rethinkstuff
 
 class UnexpectedDbResult(Exception):
     pass
@@ -91,9 +92,13 @@ class RethinkDbFrontier:
         # XXX keep track of aggregate priority and prioritize sites accordingly?
         while True:
             result = (self.r.table("sites")
-                    .between(["ACTIVE",False,0], ["ACTIVE",False,250000000000], index="sites_last_disclaimed")
+                    .between(
+                        ["ACTIVE",False,rethinkdb.minval],
+                        ["ACTIVE",False,rethinkdb.maxval],
+                        index="sites_last_disclaimed")
                     .order_by(index="sites_last_disclaimed").limit(1)
-                    .update({"claimed":True,"last_claimed_by":worker_id},return_changes=True)).run()
+                    .update({"claimed":True,"last_claimed_by":worker_id},
+                        return_changes=True)).run()
             self._vet_result(result, replaced=[0,1], unchanged=[0,1])
             if result["replaced"] == 1:
                 site = brozzler.Site(**result["changes"][0]["new_val"])
@@ -108,7 +113,7 @@ class RethinkDbFrontier:
 
     def _enforce_time_limit(self, site):
         if (site.time_limit and site.time_limit > 0
-                and time.time() - site.start_time > site.time_limit):
+                and (rethinkstuff.utcnow() - site.start_time).total_seconds() > site.time_limit):
             self.logger.debug("site FINISHED_TIME_LIMIT! time_limit=%s start_time=%s elapsed=%s %s",
                     site.time_limit, site.start_time, time.time() - site.start_time, site)
             self.finished(site, "FINISHED_TIME_LIMIT")
@@ -177,7 +182,7 @@ class RethinkDbFrontier:
 
         self.logger.info("all %s sites finished, job %s is FINISHED!", n, job.id)
         job.status = "FINISHED"
-        job.finished = datetime.datetime.utcnow().strftime("%Y-%m-%dT%H:%M:%SZ")
+        job.finished = rethinkdb.utcnow()
         self.update_job(job)
         return True
 
@@ -185,13 +190,13 @@ class RethinkDbFrontier:
         self.logger.info("%s %s", site, status)
         site.status = status
         self.update_site(site)
-        if site.job_id: 
+        if site.job_id:
             self._maybe_finish_job(site.job_id)
 
     def disclaim_site(self, site, page=None):
         self.logger.info("disclaiming %s", site)
         site.claimed = False
-        site.last_disclaimed = time.time()  # XXX use string or rethinkdb time type?
+        site.last_disclaimed = rethinkstuff.utcnow()
         if not page and not self.has_outstanding_pages(site):
             self.finished(site, "FINISHED")
         else:
diff --git a/brozzler/job.py b/brozzler/job.py
index 276f924..ff6858a 100644
--- a/brozzler/job.py
+++ b/brozzler/job.py
@@ -4,6 +4,7 @@ import yaml
 import json
 import datetime
 import uuid
+import rethinkstuff
 
 def merge(a, b):
     if isinstance(a, dict) and isinstance(b, dict):
@@ -26,18 +27,18 @@ def new_job_file(frontier, job_conf_file):
 
 def new_job(frontier, job_conf):
     job = Job(id=job_conf.get("id"), conf=job_conf, status="ACTIVE",
-        started=datetime.datetime.utcnow().strftime("%Y-%m-%dT%H:%M:%SZ"))
+        started=rethinkstuff.utcnow())
 
     sites = []
     for seed_conf in job_conf["seeds"]:
         merged_conf = merge(seed_conf, job_conf)
         # XXX check for unknown settings, invalid url, etc
-    
+
         extra_headers = None
         if "warcprox_meta" in merged_conf:
             warcprox_meta = json.dumps(merged_conf["warcprox_meta"], separators=(',', ':'))
             extra_headers = {"Warcprox-Meta":warcprox_meta}
-    
+
         site = brozzler.Site(job_id=job.id,
                 seed=merged_conf["url"],
                 scope=merged_conf.get("scope"),
diff --git a/brozzler/site.py b/brozzler/site.py
index 5aecc34..af030da 100644
--- a/brozzler/site.py
+++ b/brozzler/site.py
@@ -1,11 +1,13 @@
-# vim: set sw=4 et:
-
 import surt
 import json
 import logging
 import brozzler
 import hashlib
 import time
+import rethinkstuff
+import datetime
+
+_EPOCH_UTC = datetime.datetime.utcfromtimestamp(0.0).replace(tzinfo=rethinkstuff.UTC)
 
 class Site(brozzler.BaseDictable):
     logger = logging.getLogger(__module__ + "." + __qualname__)
@@ -13,8 +15,8 @@ class Site(brozzler.BaseDictable):
     def __init__(self, seed, id=None, job_id=None, scope=None, proxy=None,
         ignore_robots=False, time_limit=None, extra_headers=None,
         enable_warcprox_features=False, reached_limit=None, status="ACTIVE",
-        claimed=False, start_time=time.time(), last_disclaimed=0,
-        last_claimed_by=None):
+        claimed=False, start_time=rethinkstuff.utcnow(),
+        last_disclaimed=_EPOCH_UTC, last_claimed_by=None):
 
         self.seed = seed
         self.id = id
@@ -28,7 +30,6 @@ class Site(brozzler.BaseDictable):
         self.status = status
         self.claimed = bool(claimed)
         self.last_claimed_by = last_claimed_by
-        # times as seconds since epoch
         self.start_time = start_time
         self.last_disclaimed = last_disclaimed