I have been using AlgaeCal and Strontium for two years, daily and consistently. I weight train 2-3 times a week and now can manage 55 poundweights on machines, 15-20 pounds with free weights. It took 2 years to get there. And I do band resistant training once a week as well as HIIT once a week for 20 minutes. Sometimes I walk and I do garden.
My diet is vegetable based, with fish 2-3times a week. No sugar, additives, or white flour, I eat low carb because of gluten intolerance. I eat sprouts, nuts and seeds for protein.
After my 2nd DEXA I saw a 6% increase in my lumbar spine bone density. 2% in the femoral head and 1 % in the hip. I didn't go backwards...but didn't break records either. I am stronger, and satisfied with my progress.
I never had side effects to the Strontium or AlgaeCal products.
This is an anecdotal note, but I have several friends that use AlgeaCal, healthy diets and exercise and they are doing well too.
Hope that helps