Sounds like it is just you and Tank in your household. If so, Tank's needs are not being met during the night when he needs to go out and you are at work. Have someone come to your house to take him out, if you aren't able to leave work to do so. During the day when you are sleeping set the alarm to take him out on a regular schedule also.
Here are some general guidelines that I found to increase your chances of success.
- First thing in the morning when he wakes up.
- About 15 minutes after drinking water.
- About 30 minutes after eating.
- Immediately after waking up from a nap.
- During any excitement, such as when you arrive home or guests come to visit.
- At least once every hour during the day.
- Last thing at night.
Of course puppies are individuals and you may need to tweak or adjust to fit your puppies needs.
Good Luck!