A PH tester like the one I have pictured around here somewhere only costs a few bucks and is plenty accurate enough for testing tap water for our needs. Sticky is correct about the stunting and my bet is once your water is corrected they'll take off after a week or so. You can use either bulb during veg but MH is better however I recommend using both and rotating the plants or lights to cover entire grow with both bulbs. Yes it will double your grow's elec usage however you'll see much better results at harvest with fuller, denser and longer buds.