The size (ie gals) does not matter. You need enough air flow or CFM to do the job. The big units have over 100 cfm. Some recommend at least 40 cfm. I rented a 15-20 cfm unit since no body rented a 40, and it did the job just fine. My system is 3/4 poly, with no sprinkler heads - it is just a burried system to provide water at remote locations. I collected the water at the outlet of the system, and all water was out in a few minutes. Most home compressures only have about 5 cfm. It might be of interest to know how to connect the unit. I took off the standard compressure connector (screws to the hose) and the remaining piece fit just perfectly in 1/2 inch hose, which I connect to the system.

vvesper- There is a cv of River Birch that is very heat tolerant. Came out of Georgia I believe called Betula nigra 'Dura Heat'. It does have a little smaller leaf. The White Bark Birch that Dax mentioned is Betula papyrifera, the Paper Bark/White/Canoe Birch. They are beautiful trees, and the ones Indians used to make canoes out of, but I'm afraid you will have problems growing them. They are rated to Zone 7, but they DON'T like humidity. Grandpa had a huge one on his farm in western Ohio growing up, I have tried to grow them, but the years I planted them were rough, and they never made it. I think I still have a couple potted up out in the nursery, but I can't remember for sure. I want to grow one in my yard. I used the Hybrid Poplar behind the Spruce and inline with Thuja to get height and block the neighbors house. I planted them all as 6-12" tall sticks in the middle of a blazing HOT July of 07 with a terrible drought. I watered them through August and then forgot about them. The ones that have been left to mother nature are about 6-10 feet tall, and there are a few on the back of a planting bed that are nicely mulched and very occasionally watered (not intentionally, just catch the sprinkler when watering the bed) and are pushing 20 feet or better with a lush full canopy and a trunk caliper of 8-10". I'm contemplating cutting those two down already b/c I'm not sure I like them there and are starting to put off a lot of shade. That gives you an idea of how well they will fill in and grow to block the view, but they are still small enough to cut down easily. Not to mention that I paid about $2 a piece for them. Def. got my money's worth. Eliot

I posted this earlier but I always water by hand. Last summer, my alarm would go off and before I even brushed my teeth, I was outside with the hose watering the veggies. I found it to be a great way to start the day. And by doing it by hand, I was able to look at each plant and see what was going on. Sometimes I missed the morning watering because I was so busy. When that happened, I made sure to get out there at the end of the day. Took a glass of wine or a beer, got the hose and watered. And relaxed, knowing that for once, I can see the results of my hard work and labor grow before my eyes.

I have a 1500 gallon built-in wildlife pond w/ waterfall (moving water helps with attracting things) in my double lot yard. It attracts the local box turtles, tons of dragon flys & other insect as well as a myriad of birds. The most unusual is the sharp-shin hawk which has bathed there the past 2 winters. The squirrels & other local mammals also use it. We keep a red eared slider & a native mud turtle as well as native fish. We also have mosquito fish (gambusia) & have had no problems with mosquitos. We keep the fish in our rainbarrels too & they are equally free of larvae. It sounds like you have room & if so I would definitely advocate a pond. It does take some maintenance but I would say it can't be beat for wildlife attracting ability. If you do make one be sure to put in a shallow area for the birds to bathe in. We collect rainwater to fill ours & suplement with city water if absolutely neccesary.