Yes. Do NOT take magnesium oxide as it's very poorly absorbed. You might as well eat rocks because it's not going to do you any good. The best form to take is magnesium glycinate or chelated magnesium. Magnesium citrate and taurate are ok also.
Shoot - I forgot to mention it was on March 20th. That way you don't have to search back very far. Should be quicker.
Well, I didn't scan all the way back but recently Steph4501 (post titled "Magnesium") shared a website about supplements. Probably covers how much to take. Be aware you can take too much and mag. can be toxic. More isn't always better. Perhaps that website will help.