I've not actually used it yet or worked out ppm/ec I'm still in early stages of veg.
Apparently like silicon it's best applied as a foliar feed, i don't like foliar feeding so I'll be putting it into the roots.
I am not a fan of foliar feeding either. I have had issues in the past that put me off.
My problem is that I am having a minor calcium deficiency on a few plants in the latter stages of flowering, which shouldn't be as they get more than enough calcium. I think I have figured out why it is happening, but I won't know if I am right until my next run. So I want something to go to if I need it.
I could just use CalMag, but I don't like that for a number of reasons. Mainly it is the price. Like you say I can get Epsom Salts in a huge bag for £1.99 and I can get enough calcium chloride for years for £9.99. My other problem with Calmag is it contains Nitrogen. I don't really want to be adding more Nitrogen in flower.
I have a friend who is a Chemist and he sees no reason why Calcium Chloride can't be applied to the roots as part of a mixed solution or as a top dress, the question he can't answer is how much? The best answer I can come up with is from a veg growers forum that suggests 5g per Imperial Gallon of water.