Greetings!

I am a COMPLETE novice and could really use your advice. For a little over a year, I've had an Areca palm in a very large clay pot inside my pool cage (approximately 5-6 ft tall). About three weeks ago it started to get a little yellow. I thought it was because I wasn't watering it enough. I had been filling the pot to the top approximately once every two weeks. Once it started yellowing I started filling the pot twice a week for about three weeks in a row. (there is a drainage hole, but I don't think it actually drains). This week there were at least 6 new fronds growing out, but three large stems with new fronds growing out of them literally fell off. The stems were completely mushy like they were rotted. It's a shame, because it was obviously growing. Am I watering it too much?