Creamy starter won't stay bubbly or float
I have probably about 3 cups starter in the jar. It is two weeks old and smells deliciously sour. I remove about a half cup each day and replace with half cup water and half cup flour. It doubles in size but then quickly deflates. I can't keep it bubbly and get it to float so I can use it. What am I doing wrong? I started it out on the counter for 6 days. Refrigerated it 3 days and now it had been out on the counter again for several days.