Originally Posted by Babyboomerboy
I think you a little short on air intake. If you go back and read how to build a UDS, you will see that the plan was for 3 1" holes a couple of inches off the bottom. Then install 3 3/4" threaded nipples into these holes. Cap off 2 of them and use your 1" valve on the third. Remember what all these guys say about changing the proven UDS plan on your first build, kiss.
I set my latest up with 4. Maybe overkill, but on other sites it has been suggested that 4 can offer more control in windy situations