The new diet: struvite crystals vs. tarter...

The Els, my 6 y.o., 10.5 lb, Hurricane Katrina-rescued female tabby, was recently diagnosed as having a plethora of struvite crystals in her urine (7.5 pH).

During the two years that I've entertained her presence, she's eaten nothing but Innova reduced fat dry, topped with a spoonful of Evo wet. Gourmet vittles, for sure! After her diagnosis, the vet put her on Hills s/d for two weeks, to be followed by Hills c/d for the remainder of her kitty nine lives.

I've read on this site that better quality diet options exist to address urinary/struvite issues that include:

*low magnesium
*low calcium
*no seafood
*preferably wet

My questions:

1. What foods should I further research that are UTI friendly/certified? (I've heard Nutro Max cat roasted chicken, as well as Purina Pro Plan, mentioned previously)

2. Should I base my decision primarily on low magnesium levels? (considering other quality ingredients, of course)

3. My cat also has a tarter issue. Although I've read that wet food is preferable for urinary health, would dry be a good compromise to provide some tarter-scraping benefits?

Thanks for your insight!

1... ones that have been or are being UTI tested = many RX s and nutro max and pro plan urinary and one urinary

2... magnesium is in dry.085% ( could be .85% no foods in my house list it ) is the better .09 is the ABSOLUTE highest.... In wet .025% is the HIGHEST ....022 preferred

3.... ONLY a few LIKE 4 DRY foods HAVE been tested and tested that they reduce tarter ... on a whole CATS dont CHEW so dry food is a conveince for us not them... wet can help keep tarter under control as can reg toothbrushing or some other dental aids

Since I have three cats and do not want to have the headache of feeding different foods, nor do those foods seem to be very appetizing to most cats, I use Carpon an acidifier, that keeps Fang's PH where it should be so the struvite crystals do not form, or dissolve quickly enough that they are not a problem.
http://www.belfield.com/carpon.php