New Masher - Sluggish Fermentations

I've done two mashes so far. The first one was a small all grain batch using DeathBrewer's stove top mash method. The second one was a partial mash using Bobby_M's cooler MLT.

Both times, the fermentation has been sluggish. The blow-off tube would start bubbling after about 24 hours, and then quit after about 8-16 hours of activity (getting stuck around 1.019-1.022). For both batches I pitched sufficient yeast according to the mrmalty pitching rate calculator.

My water is real low in Mg and for both brews I diluted my tap water by at least 67%. For one, I didn't add any Mg back at all, leaving the wort with less than 1ppm. For the other, I added Epsom salt to give me about 5ppm (plus whatever Mg is in 2.5lbs of Munton's Amber DME).

My question is, can the low Mg concentration in my water be the source of my problems? I never worried much about the Mg concentration since Palmer says that the malt usually provides enough Mg nutrient for the yeast.

Thoughts?

I've never had to worry about Mg (but I may just be lucky). What kind of yeast have you been using? Starters? What is your efficiency?

Yeah my first question would be, are you hitting your target OGs?

Batch 1 (~1ppm Mg) was an all grain wheat, 3.5 gallon batch from here:
https://www.homebrewtalk.com/f70/crop-circle-wheat-clone-65816/
For that batch, the mrmalty calculator recommended pitching 1.3 Activator packs, so I pitched 1 pack of Wyeast 3068. I did hit my gravity of 1.052 and had a mash efficiency of 82%. Fermented at 68F. Blow-off tube started bubbling after 24 hours and stopped less than 8 hours later. About 12 hours after that, I took a gravity measurement of 1.019, stirred up the beer and had more blow-off activity for 2-3 days. Finished at 1.013 (dead center of range for 3068), but it required the stirring.

Batch 2 was a partial mash ESB. I ended up having 73% efficiency and an OG of 1.056. For this batch, I got 62% of my points from the mash and 38 from Munton's Amber DME. The water I used had ~5ppm Mg, and the final wort had more (whatever came along with the DME). 24 hours prior to pitching, I made a 1.5L starter for this, which was exactly what the mrmalty calculator recommended. I used an Activator pack of Wyeast 1968. I fermented at 68F, and after about 16 hours I decided to rock the fermenter since this strain tends to drop out early. Immediately after, I had blow-off activity of about 30 bubbles/minute. That lasted anywhere from 12-19 hours (stopped some time in my sleep). At 48 hours after pitching, I tried rocking the fermenter. The blow-off tube wouldn't start up again though. I measured the gravity at 1.022. You can find more details about this one in this thread:
https://www.homebrewtalk.com/f12/wyeast-1968-london-esb-experience-127716/

I just noticed a common theme that once I started mashing, my fermentations became sluggish. It could just be a coincidence along with the strains that I'm using. I know for a fact that 1968 can be picky especially at low temperatures. Also, another person reported a stuck fermentation with 3068.

One other factor for sluggish fermentation is aeration. Maybe your wort isn't aerated as much with AG the way it was when you were doing extract. I've got soft water myself....but I haven't noticed a lack of minerals does much for the attenuation. I only add minerals during the boil for styles that need it: my mash pH always seems to be in line. Getting an oxygen tank really got my fermentations to take off.

What temperature are you mashing at?

For batch 1, I planned to mash at 154F. My thermometer was faulty and I wasn't able to control my temp on the stove very well. I originally thought I mashed higher than 154F, but it eventually fermented down to 1.014 (it just took the stirring).

For batch 2, I had much better control since I mashed in a Rubbermaid cooler. I did hit my mash temperature of 149F. I also added 2oz. of corn sugar to the boil to get more attenuation since 38% of my gravity came from DME.

Don't judge fermentation activity by the airlock or blow off. It may be at 1.022 now but it sounds like its only been in the fermenter since sunday. Once the yeast goes in and it looks like fermentation has started I don't touch my beers for at least two weeks. I've had plenty of beers that started off fast, but took weeks to get to FG.

jrkettle said:

Don't judge fermentation activity by the airlock or blow off.

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You're right. I should know better.

davesrose said:

One other factor for sluggish fermentation is aeration. Maybe your wort isn't aerated as much with AG the way it was when you were doing extract. I've got soft water myself....but I haven't noticed a lack of minerals does much for the attenuation. I only add minerals during the boil for styles that need it: my mash pH always seems to be in line. Getting an oxygen tank really got my fermentations to take off.

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Aeration is one area I think I can improve in. For all of my brews, I've used a Venturi tube nearly identical to the one in this post:
https://www.homebrewtalk.com/f51/cheap-easy-aeration-gadget-68218/index4.html#post974317

I insert it about in the middle of my racking tube, about 2 feet from the exit. I always rack from my brew kettle to a plastic bucket. I wouldn't expect the effectiveness of the Venturi tube to change just by going to AG/PM.

Where did you get your oxygen tank?

jescholler said:

I wouldn't expect the effectiveness of the Venturi tube to change just by going to AG/PM.

Where did you get your oxygen tank?

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Yeah, I don't know what your methods were for PM to know if there's a big difference in aerating vs all grain. At least IMO, AG might have more chance for less air because you wind up boiling all of your wort instead of some of it in say extract (and there may be more chance for mixing in more air when topping off with water with extract). I was just throwing out aeration as a possiblity to eliminate. At least I found that when I got an O2 system, that was the main element that got my ferments to take off quickly (even more so then making starters). Starters and ferment temp just seem to let the ferment stay consistant and attenuate fully. All 3 factors are the main elements for full ferments IMO.

I just got a regulator and stone from my LHBS store...they fit disposable O2 tanks that you get at Home Depot for around $10. The odd thing is that I've noticed some posters on this site say they go through quite a few of the tanks because their regulators are releasing or leaking too much gas. I'm still on my first tank after many, many batches....so I don't know if there is some sort of quality control with these simple O2 regulators.

I don't think there's anything wrong with my fermentations, just me. See this thread:
https://www.homebrewtalk.com/f12/wyeast-1968-london-esb-experience-127716/index2.html#post1437677

Sorry for the troubles, but all of the advice is good stuff to make sure I have the best practices on (aeration, pitch rate, ferment temperatures, mash temperatures, yeast nutrients). Also, I didn't mean to get the same topic going on 2 different threads, but they kind of got steered in that direction.

jescholler said:

Aeration is one area I think I can improve in. For all of my brews, I've used a Venturi tube nearly identical to the one in this post:
https://www.homebrewtalk.com/f51/cheap-easy-aeration-gadget-68218/index4.html#post974317

I insert it about in the middle of my racking tube, about 2 feet from the exit. I always rack from my brew kettle to a plastic bucket. I wouldn't expect the effectiveness of the Venturi tube to change just by going to AG/PM.

Where did you get your oxygen tank?

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I'm pretty sure Orfy only uses a venturi tube from the kettle for aeration and has good results.

I use an aquarium pump for 30 minutes or so, which works fine.

I'm not sure what the issue here is. I either suspect a faulty thermometer, or the water chemistry is somehow jacked up. Since I'm ignorant of water chemistry, though, I'll have to go with the thermometer theory!

YooperBrew said:

I'm not sure what the issue here is.

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I'm pretty sure I'm the issue. My blow-off tube stopped bubbling after around 24 hours and I freaked out both times. I bet if I just let the yeasties do their job, they would have been (and are) just fine. Both of these beers will have normal finishing gravities.

I'm pretty sure my new thermometer (used on the 2nd mash) is accurate. It's a floating thermometer from Northern Brewer. I checked it at 100F with a medical thermometer, and it was on.

Just a newbie here that can't relax. This is a good lesson though.

As far as water chemistry, is there anything else I need to add back if I use mostly distilled water? So far, the things I know to watch are calcium, magnesium, sodium, chloride, and sulfate. Those together dictate hardness, alkalinity, residual alkalinity, and mash pH. Is there something else I'm missing like a yeast nutrient?

IMHO William's Brewing, Home Brewing Supplies, Winemaking Supplies, and Home Coffee Roasting. @ Williams Brewing has the best oxygen regulator/wand setup.