Gravity Hasn't Dropped In My Wort

[MrClark721]

I'm making my own recipe I know it's probably not smart for a beginner to do that but I like doing things my way that's what I love about the freedom of brewing! Anyways I am using WLP099 High Gravity Ale Yeast and you need to feed it sugar over the span of a few days so I was doing that and yesterday I added the most sugar when it was at 6% alcohol so I raised it from 11% potential alcohol to 15% so I can hit my target ABV of about 20% but it seems that there hasn't been any activity besides the sugar I added carbonating the wort which I wasn't intending for but I've been taking hydrometer readings over the past 24 hours on it and it hasn't dropped past the 15% potential mark there is also no krausen at least I don't think there is a green layer on top but I think that it's just my hops because I didn't use a brew bag. Any help is appreciated. (Also I understand people use the gravity to measure but for me I have the potential alcohol content and its easier for me to measure that way since its my first batch.) I can post a picture if that can help too i'm only on day 4!

 

[jerbrew]

Day four total? That's a lot of sugar. I'm sure there will be a more detailed and informative post shortly but it seems to me that you may have "overloaded" the yeast. By increasing the sugar content of the wort too quickly, before the yeast has had a chance to knock it down from it's OG, you have created an osmotic pressure greater than what the yeast cell can deal with or overcome (or you started too high). Essentially, the driver for moisture to leave the cell is greater than the cell can withstand and damages the cell wall of the yeast. That or it simply cannot transport food, sugar, into the cell for respiration. This is one reason you need a metric poop ton of yeast to start a high gravity beer.

Here is a short article by WYEAST talking a little about consideration for high gravity brewing. Here is another more in depth article talking about it and more consideration for high gravity brewing.

 

[davidabcd]

I think the large starter, as mentioned, is important. WLP099, in my experience, wants to continue to ferment slowly. I created gushers when I used it despite an apparent finished fermentation. That it is diastaticus is a little scary to me.
I will be interested as well to see what someone with a lot of experience with WLP099 has to say.