You do realize that using SLS will result in an instaban here right?

Seriously, though, I can't help you with volume, since I have a lot of medium/coarse hair. I use a PT about twice a week, which really helps, and a DT once a week. I think it's a good idea to do a DT weekly, unless you get OC'd quickly.

As for using a sulfate poo to get rid of hard water build up, IAgirl has done a little experiment regarding low-poos and sulfate poos. She concluded that using a diluted sulfate poo does not damage hair, so as long as you dilute it well, you should be fine. You could also use Del's Spritz&Condish method, and use a sulfate poo after you've put a lot of conditioner in your hair.

Wurly 2b/2c/3a Miii - high porosity

Cuius testiculos habes, habeas cardia et cerebellum.

Sodomy non sapiens.

- Terry Pratchett