I built my own heated phosphate tank. It was pretty easy to build because it's small. A large one would be a bit more difficult. I used a product called BSP 245. It's ok, but requires a temp of 90 to 140f, and is kind of expensive due to the amounts you have to buy. If you intend to spray it I would use a small garden sprayer and heat the solution up in a pot, pour it in the sprayer and spray the frames. You do not need to rinse afterward. Just make sure you work quickly. Go here
http://www.caswellplating.com/powder/pcprimer.html
You can buy smaller amounts and it's less expensive.