With colitis you have the additional problem that Miracle-Mineral-Supplement can sometimes irritate the stomach, and with colitis it's possible the whole digective system can have some inflammation and be prone to this depending on how bad it is
I don't think it would irritate the colon directly though but I built it up very very slowly just case. You may also have some inflammation in the small intestine. More dilution may help and split up smaller doses possibly.
I wouldn't go over the 15 drops in any case and you could get good results with less.
I diluted with pinapple juice and used lime juice to activate it at 10-15 drops and only took it in the evening. 10% citric acid with water is quite strong