I also had a high output stoma (2800 mL) and needed to be hospitalized several times for dehydration. Imodium was a huge help in slowing things down. I got the dehydration and output under control by drinking 2 L of Gatorade, 2 L of water and taking 6 Imodium per day. I didn't realize it at the time, but my output increased as I decreased my pain meds. The pain meds helped slow things down. My bag leaked all of the time before Imodium, but I never had issues after I started taking it.

I had really high output after my JPouch creation - while waiting for closure.  I think I was at 4,000cc some days.  I was hospitalized also and got a pic line for hydration.  Imodium and Lomotil helped.  It honestly took about 12 weeks for things to slow down.  Try not to drink too much sugar - that speeds stuff up.  Some say that medamucil can help bulk a bit and slow down.  There are also shots of Octreotide that slow things down super well.  I used those here and there and it kept me out of the ER.  Those are the big guns.

Thank you so much for the input

Avoid anything containing sugar. Avoid fibrous foods. Try imodium/loperamide. Take two pills/caps 30 min. before each meal. You can also try Metamucil powder or cookies before meals, which will thicken output. If there's an advice nurse  connected to your surgeon's office, run the above by them. Urgent care should have offered some advice before discharging you.

Thank you so much for your advice.