High FG question

[Borneogoat]

About 3wks ago I brewed my first AG batch in many years. I did a SMaSH of:

12# Maris Otter
1oz Cascade @ 60/20/5min
Mash for 75min @ 154F
Target OG = 1.054
Actual OG = 1.050 with about 5.5gal into the fermenter
Pitched WLP0028 at ~ 64F, 1.5L healthy starter, target FG = 1.012
Note: no pH testing or conversion testing during mash, didn't wanna play with H2O chemistry until more experienced.

I kept my fermenter at a steady 62-64F for the first week. Airlock started burping along between 12-24hrs later. Bubbled from Day #2 till Day #4 and then paused. Day#5 SG was 1.030. Day #6 she started bubbling again. Around Day #8 weather got cold and fermenter fell to ~58F at night. Bubbling stopped, SG = 1.023. I brought it back up to a steady 68F and held there since. Day #14, SG = 1.023, pitched some SA-05 hoping to kick the action back up, bubbling occurs. Day #20 (today) still SG = 1.023.

So I've concluded FG isn't going to drop below 1.023, because 2wks steady. Still a little airlock activity, bubble every 5-10min. Gonna bottle tonight, because it doesn't appear to be dropping and the hyrdo samples taste sweetish but drinkable.

What happened here; why the high FG?

I didn't test pH or starch conversion during the mash. The local water (Hobart, Tasmania) is quite soft. I added a bit of gypsum, but that's it. If my pH was high, might I have had poor conversion and thus too many unfermentables in my wort? Or something else?

Next batch is tomorrow, but now I have a pH meter and iodine....

 

[FastAndy]

That seems pretty inline with a medium attenuation yeast like WLP0028.

 

[BlueHouseBrewhaus]

Actually, it looks like you only have about 54% attenuation. First question is have you checked your thermometer? You are mashing on the high end so if your thermometer is even a few degrees off, you may have mashed too high and hurt your conversion.

You mentioned chemistry (or lack of it). With no dark grains, your pH could have been high. Not sure how/if that effects conversion. I have pretty soft water and still need acid (or acid malt) for my light brews.

Other than that, I don't have any other suggestions. MO should convert very well and your starter seems to be big enough. Your temps are OK. WLP28 should give you decent attenuation.

 

[Nate]

Second the thermometer check. As Blue House stated, just a few degrees and what you're seeing is expected.

 

[pricelessbrewing]

I have to ask, are you using a hydrometer or refractometer?

 

[Borneogoat]

I've confirmed my mash thermometer is good. Tested against a Thermapen and less than 1F difference.

Yes, hydrometer. Which I've double checked against water, but not a known wort SG. I'll try that this week.

Currently mashing for the next brew. Got some chocolate malt & acid malt in this recipe. Going smoothly and we'll see what happens. I expected to use an iodine test and pH meter this time, but a fail on both! pH sensor requires distilled water to calibrate, none available, and I can see the out-of-box calibration is off significantly. Tried the iodine test at 10/20/30/45mins. No black tinted reaction! So I've either got no starch at all (not likely!) or the iodine is not the right stuff. Using Betadine Antiseptic Liquid with 10% Povidone-Iodine = 1% available iodine.

I guess .... relax, have a beer and a BLT!

 

[Borneogoat]

Follow up for future readers. Upon very careful retesting my hydrometer in DI water and then a wort of known gravity, my hydrometer was waaaaay off! New lab grad hydrometers on the way and the old one will be junked.