Hi all, any help on the matter will be greatly appreciated. I recently generated bacterial pour plates using the protocol for artificial sea water medium (Kester et al., 1967). I separated the volume in half and added two different carbon sources (fucoidan to the first 500ml and alginic acid to the second 500ml). After autoclaving and while pouring the plates in a sterile fume hood, I noticed that the plates containing alginic acid did not set properly. What may be the possible reasons for this?, may it simply be, that more agar must be added to the protocol, or possibly that the high pH of the tris base (pH 11) is interacting with the alginic acid?