Nanomano, I can tell by looking at your tank that the alkalinity is
not at 27 dKH. I think you goofed on the test. Re-read the instructions from beginning to end, then test again following the steps one by one. The alkalinity kit is really easy, and the API alkalinity kit is actually quite a good one even though it is cheaper. The Salifert alkalinity kit will test 1-2 dKH higher than it actually is, so I don't like Salifert for alkalinity, but API and Elos are both good for alkalinity and will both give you a really similar reading.
IIRC, the API kit is 1 drop = 1 dKH. First it turns blue, then it turns yellow. When it is clear yellow you stop adding drops. Is that what you did? Did you have to add 27 drops to get it to turn yellow? I have a feeling that the dKH is half of that, and you goofed some weird calculation you did...?
The AragaMILK is essentially really, really fine aragonite sand and at saltwater pH values it will not dissolve. It doesn't really do anything at all.
Reef Crystals out of the bucket will be around 500 ppm calcium, 8 dKH, and mg I can't remember. Mix up a batch of saltwater (to 35 ppt or 1.025-6), let it mix with a powerhead for 24 hours. Double check salinity then test calcium, alkalinity, and magnesium. This will tell you what the waterchange water is, which is important to know. Are you using tap water or RO or RO/DI?
Since you got your hydrometer calibrated, you can still use it will no issues. Just remember to re-calibrate it every 6 months.
From Wetaskiwin, Blue World is probably the closest "REAL" saltwater store to you. It is actually only a few blocks away from the Big Al's in the south end. Go there instead!
Red Coral in the north end is good too, and Aquarium Illusions is up there too (more west of Red Coral), but I haven't talked much to the staff at AI so I can't vouch for them.