Last week I had fermented a beer that used WLP002 English Ale Yeast. I created an extra big starter and decanted when I used it in my other brew but the rest I poured into a ball jar and topped off with fresh room temp seltzer water. After leaving it in the fridge for a week I noticed a greenish layer on the top, should I be concerned? I am currently making a starter with this for another beer, should i not use it? Should I try and decant that green layer? Anyone ever see anything like this? Could it be malt and proteins from the starter?