How much headspace is too little

[Sonikos]

Hello,
I have a conical stainsteel fermenter 26lt and I want to make a 23lt batch (Mangrove Jack’s New Zealand Brewer’s Series Pale Ale). Is the 3lt headspace too little? If it is, I could devide the batch in two parts (because I have a small plastic fermenter). But in that case how can I devide the yeast correctly? I suppose I will need a precise kitchen scale. Any ideas? But first of all, will I have a problem with the 3lt headspace? Could I put less water and make it a 22lt batch? Thank you very much in advance!

 

[SBENCIV]

I personally wouldn't divide the batch or use less water. I would probably just roll with it as is. Do you have a blow off tube on your fermenter? Or is it a spunding valve?? If it's a blowoff - I definitely wouldn't worry as any excess krausen would just spill out through the blowoff tube. But if it's a spunding valve, then yes, I guess you may want to be cautious as you wouldn't want to gum up the valve. Also tough to know how vigorous fermentation will be. You could also add a foam control for fermentation such as Fermcap-S as some added insurance? Sorry, I know this isn't much of a direct answer.