Alk supp precipitating?

[alten78]

Recently ive had a rough time maintaining cal and alk just to find my mag was low. I mixed up a batch of Randy's 2 part solution (#1 recipe,) got my mag where it needed to be, and used the online calculator to see how much I needed to bring all levels within range. Dosing the calcium part seems ok, but when I drip the alk portion, it looks to precipitate out of the water? Im assuming this is the calcium carbonate (if im reading and understanding correctly?)

Not exactly sure where I went wrong, I've used this method of dosing about a year ago but I don't remember running into this problem. Any thoughts are greatly appreciated!

Thanks