I am assuming you diluted that. If not, that could be the reason.
I usually dilute 1 bottle of Mag citrate laxative with 3 bottles of drinking water and drink that over a period of 2 hours first thing in the morning. Diarrhea starts around noon and done by the end of the day.
Ugh I didn’t dilute. Now I feel dumb. My prep instructions were to drink 3 cups of water 3 hours before and then 3 cups of water after drinking the prep. Thanks for the response.