Water Hardness and Calcium

Just listening to the Brew Strong show on water analysis right now. I notice that my Calcium is way too low. But the total hardness on my report isn't too bad. Palmer says you can estimate that you have a calcium:magnesium ratio of 3:1 or 4:1 and determine the calcium from that. Eg 50ppm total hardness = 10 magnesium and 40 calcium assuming 4:1. Here's my water report

Total Alkalinity (as CaCO3) - 48.9 mg/L
Total Hardness (as CaCO3) - 54.5 mg/L
Chloride ------------------- 1.07 mg/L
Sulfate -------------------- 8.0 mg/L
Calcium -------------------- 16.9 mg/L
Magnesium ----------------- 3.0 mg/L

I have been struggling a bit with cloudy beer, so it's possibly my calcium is so low that I'm not getting proper flocculation. I'm going to get some salts and adjust my calcium. But I'm wondering why the hardness correlation that Palmer gives, doesn't seem to match up here.

I found a similar thread:
https://www.homebrewtalk.com/f128/total-hardness-calcium-magnesium-153586/
With a link to Palmer's Site:
http://howtobrew.com/section3/chapter15-1.html

I guess total hardness is not equal to Ca (ppm) and Mg (ppm):

(Ca (ppm)/20 + Mg (ppm)/12.1) x 50 = Total Hardness as CaCO3

My units are in mg/L on my analysis, with if you talk ions in equal to ppm, but not when talking molecules (CaCO3). So I believe the below statements are true, but I'm just guessing at this point:

Ca (ppm) + Mg (ppm) = Total Hardness as CaCO3 (ppm)
Or
Ca (mg/L) + Mg (mg/L) + CO3 (mg/L) = Total Hardness as CaCO3 (mg/L)