I have a number of commericial accounts where there are hundreds of annuals to water/fertilize every couple of weeks. Did a search and there wasn't allot there on backpacks. What brand and model would you recommend? Lesco was mentioned as well as Echo and something Home Depot sells. Dont need the casillac of sprayers...rather, larger capacity, reliable, and holds pressure. If you could note the price that would be appreciated...thanks.