A friend who is a Master Gardner said to never mix ferts, and or additives at all. Basically she said you don't want to fert your plants every time you water so rotate what you fert each watering. Example if you water 4 times a week the first watering fert with your bone meal, watering 2 use your calcium, 3 Epsom salts, 4 fish emulsion etc. She said most of the time this will be your safest way to feed the plants. Although you may be able to add everything in one batch it may or may not cause a problem and is probably not worth the risk. I have been doing my ferts this way and haven't had any issues.