I just found out, my less than half full bottle of Dektol and XTOL solutions have the appearance of air being sucked out. That is, the plastic bottles have significantly caved inward. Fixer bottle is unaffected. Is this a result of these chemicals absorbing air and as a result creating vacuum inside the bottle? How do I prevent this. These bottles are only few weeks old since mixed to full strength. Nearly full bottle is unaffected.