Small batch Issues

Hi gang,
              I have a question regarding small batch. I have done 5-6 all grain tradition 5 gallon batchs with complete success. I have dropped to small batch ( 1.5 gallon ) to try out special recipes. I did two batches about 3 weeks ago and then another two last night. Here is the question; what is killing/ delaying my fermentation?
The batched from three weeks ago never took off.
No, I have not done a recent SG check. I will tonight to r/o a missed observation of fermentation.
Originally I thought it was temperature. The second session I kept/will keep upstairs where the ambient temp is 68-70. The OG of the first two batches were 1.07 &1.072; last nights batches were 1.07 & 1.068.
My basement is 62-64. The yeast WLP002 was done in a starter ( perfect - no issues) in both sessions. These are variables I think may be at fault.

Too low ambient room temp.
Too low of a pH - the water I used was Dasani bottled water ( original pH is 4-5 per the interweb) I do not have a pH meter so I do not know what the wort pH is.
Scalding of mash grain ( 1st session only ; last night went perfect at 153-154 ) - my thermometer was off / broken 3 weeks ago and I lauteres above 170.
Grain amylase concern - I smoked 2row American and it was <6% of the entire grain bill; I smoked the grain at 170~

I have never had an infection; and I am not concerned about that problem.I am meticulous about staying sanitized.
I use Star-san ; can a too high of a concentration kill/stress the yeast? I usually make 3 gallon batches and use .75 ounces of concentrate.

I will grab a SG in the three week batches.
Last nights effort was not bubbling this morning.

Thanks,
C

Are you using a different fermentation container? I had a similar issue when I started doing small batches. I used a glass carboy for the 5-gallon batches but used smaller buckets for the small batches. The buckets don’t seal well and I never saw any airlock activity. But a gravity measurement after a week proved it had pretty much fermented all the way through. Only way to be sure is to take a gravity measurement.

It’s difficult to say.  For whatever it’s worth, I usually make 1.5 to 2-gallon batches these days, and I don’t notice a lag or anything different about the fermentation compared to the occasional 5-6 gallon batches that I do about once a year.

As you suspect, the batch size itself has nothing to do with it.  Let,s not get distracted by that and look for a real solution.

Tim: I have a sneaking suspicion that may be the problem. I had thought that the seal was not “tight” I will check my SG and compare.

D: what are you using for fermenting vessel?

Thanks,
Clint

I use 3-gallon carboys or 1-gallon pickle jars, depending on whether I split the batches.  All glass, not plastic.

I use 5 gal. buckets for 1.25, 2 and 3 qal. batches, as well as my usual 5.5 gal. batches.

Update:
            I finally got to check a SG. I was at 1.051, the OSG was 1.072-1.073.
It seems I got a short amount of fermentation. I could even see a trace amount of Krausen. When I spoke with my local brew shop guru he said I scaled my grains - my thermometer was broke and I guessed at the temp of my strike water. I know I was above 170f.
The batch is phenomenal- just low alcohol and not “finished” thoughts on how to proceed? Should I just dump it and start over?

Thanks,
Clint

Try adding Nottingham ale yeast.  It can eat maltotriose, which WLP002 cannot eat.  This should help.

Look up fast ferment test. It’s a very easy way to find out if the wort will ferment more.

How are you making your smaller batches? I brew mostly smaller batches exclusively (1.5 gallons), but my mash is done with the BIAB method. I haven’t had any issues with fermentation, but have my process pretty well dialed in.

What kind of ambient temp is your fermenter sitting in? If you’re under 60 degrees, that could be part of the problem. Yeast might be dormant and need to be “waken up” a bit.