Hi, Melissa - Chloe is lovely!  Thanks for the case history - good work.  What breed is she?

I went and double-checked the All Phase stats.  Starch in the products varies from 10% to 12% (much, much too high for any IR horse, even fed at the recommended rates) and ESC from 5% to 7% or so. I can tell you from experience that one of my mares can't tolerate more than half a pound (250 grams) of the Pro Fibre Crunch, which is only 4.5% starch and 4% ESC. (so she doesn't get any, to her annoyance)

The Step 7 supplement comes in at a whopping 29% starch, unfortunately.

Since you are in Victoria, I assume you can only get stuff from Otter Co-op, not from Champion?  The Otter beet pulp pellets are quite variable in molasses content; interestingly, my horses won't touch them, although they will eat the Pro Form and the Champion beet pulp pellets just fine. (all being rinsed, soaked, rinsed, of course) If you can get the Step 7, you should be able to get Pro Form beet pulp (same company)  They also make soy hull pellets.

To determine what minerals to feed, testing the hay is better than blood samples (except selenium and vitamin E) The other minerals don't show up as abnormal in the blood until they are seriously and wildly out of whack in the tissues.  The only real way to check mineral stores in the body is by liver biopsy, but nobody in their right mind would do that as a routine check! So testing the hay is the way to go (although doing blood selenium and E is still nice, especially if you need to check for excess selenium)

I use Hi Pro for a quick turn-around test if I am trying to figure out what hay to buy, but once I get the hay home I send a sample of 20 or so cores to Nutrilytical in Calgary. http://www.nutrilytical.ca/  They are affiliated with Equi Analytical in New York, and will send the sample on.   Ask for Trainer # 603

In the meantime, commercial supplements that are good to use while waiting for the analysis are California Trace and Arizona Copper Complete.  Both are from the States, unfortunately, so shipping is a killer.

In Canada, the Mad Barn Basic Mineral Mix is good for Alberta hay (but too high in manganese for BC hay), although there is selenium in there as well:  https://www.madbarn.com/product/madbarn-trace-mineral-pak/ There are no major minerals in it, but it is easy to add a teaspoon or so of magnesium oxide.  The owner of Mad Barn (whose name escapes me at the moment) has also expressed an interest in doing custom mixes for Canadians.

Other choices are Dr. Reed's No. 2 mix, and Hoffman's Performance mix (again, too much manganese for BC, and one has to add magnesium)

Vitamin E has to be touching oil to be properly absorbed, so most of us use 400 IU capsules with soya oil in them. One has to read the label, because some are manufactured with just glycerine and no oil.  I get mine from National Nutrition Canada http://www.nationalnutrition.ca/

Hope that helps!