I don't have any meters, the water is well water (what my house has) so it doesn't have a lot of the additives city water has. Using MG tomato, what if always used and mixing at 1tbsp/gal, 8 gal in res. Temp of water varies, 56 to 70f, mostly mid ways of that set.
I just started a hydro with my well water, It started at 550 ppm but after reverse osmosis its literally 7 ppm. That gives me literally full control over my water instead of like 50%. I know its expensive but I would strongly suggest getting a RO setup.
If you cant, i'd suggest doing an organic soil; where PH matters the least.
But, if you want to stick with your current hydro, or if you have learned to work with your water; then a simple tote bin hydro setup will work great for starting your plants.
I would maybe try to get some better nutrients than Miracle Grow. I use CX hydroponics, if you email them you can get a full sample pack for the price of shipping; like $30. Easily my favorite hydro nutrient line; i almost never have to PH my water after mixing the nutes and my plants are healthy as hell.
Again, just some thoughts