Gravity Reading from a Fermzilla?

[Brewelder]

Hi All,

I’ve just acquired a Fermzilla (Gen3) and plan to do a brew over the coming weekend, it’s either going to be a NEIPA or a Neck Oil clone both from the good folk at KegThat, I just haven’t decided which one to do first yet.

But, not having used the Fermzilla yet i was wondering how to take a gravity reading once the fermentation is under way? Both kits being susceptible to oxidation i didn’t want to open the lid to take a reading. Also after fermentation is complete both brews will be close transferred to kegs So how do i get an accurate reading?

 

[Rwilts]

Will you be fermenting under pressure and/or access to CO2 and do you have the floating Dip tube?

 

[Brewelder]

Will you be fermenting under pressure and/or access to CO2 and do you have the floating Dip tube?

Yes i have C02 & the dip tube, but not sure wether to ferment under pressure or just like a closed ferment with the spunding valve set at a couple of psi

 

[Rwilts]

Yes i have C02 & the dip tube, but not sure wether to ferment under pressure or just like a closed ferment with the spunding valve set at a couple of psi

I think your only options are to inject some pressure and draw sample from dip tube. Or. Open the lid ... I use a ispindle it's not brilliantly accurate at later stages but is reassuring that fermentation is ongoing

 

[Theoriginalrich]

I also use an ispindel, it’s the only readings I do and trust what ever numbers it kicks out. It gives you an idea how things are going.
I’ve got my Tropical England in at the moment, day 4 and pressured at 2.5 psi.
The really good thing about the Fermzilla that I can never got bored at is watching your brew at work when fermenting, amazing.

 

[Rwilts]

I also use an ispindel, it’s the only readings I do and trust what ever numbers it kicks out. It gives you an idea how things are going.
I’ve got my Tropical England in at the moment, day 4 and pressured at 2.5 psi.
The really good thing about the Fermzilla that I can never got bored at is watching your brew at work when fermenting, amazing.

Best lava lamp in the world.

 

[Brewelder]

I think your only options are to inject some pressure and draw sample from dip tube. Or. Open the lid ... I use a ispindle it's not brilliantly accurate at later stages but is reassuring that fermentation is ongoing

I don’t have an iSpindle so i guess the only way is to draw some off via the liquid out post

 

[Rwilts]

This youtuber has a lot of videos on fermzilla (gash I think)

 

[buddsy]

I usually open the top and use a wine thief. Theres a blanket of CO2 in there so will be fine.

buddsy

 

[hoppyscotty]

Well I have an ispindel to monitor trend and pay little attention to the actual value. I only take hydrometer readings after a good 4 or so days of no change once it looks like fermentation is completely done and take one hydrometer reading at that point to confirm FG. I don't see the need to monitor gravity during fermentation unless you're looking to add hops or change temp profile based on gravity. But if no ispindel the I use a party tap to pull some off.

 

[Brewelder]

Well I have an ispindel to monitor trend and pay little attention to the actual value. I only take hydrometer readings after a good 4 or so days of no change once it looks like fermentation is completely done and take one hydrometer reading at that point to confirm FG. I don't see the need to monitor gravity during fermentation unless you're looking to add hops or change temp profile based on gravity. But if no ispindel the I use a party tap to pull some off.

I need to get a party tap, i reckon i could improvise as i have a few valves which would act as a tap when connected to the liquid out post i guess?

 

[Brewelder]

I usually open the top and use a wine thief. Theres a blanket of CO2 in there so will be fine.

buddsy

I’m sure this would work but don’t want to risk opening the fermenter to atmosphere

 

[buddsy]

I’m sure this would work but don’t want to risk opening the fermenter to atmosphere

What is the risk? You are going to drop something in?

buddsy

 

[Brewelder]

What is the risk? You are going to drop something in?

buddsy

Possible exposure to oxygen mate.

I’m sure your method might work, but i just don’t want to risk opening the vessel up during fermentation.

 

[Agentgonzo]

Theres a blanket of CO2 in there so will be fine

The blanket of CO2 is a bit of a myth. Yes, there is CO2 filling the headspace on top of your fermenter, and yes, CO2 is denser than air, so it won't immediately escape the fermenter when you remove the lid in the way that, say, helium would.

However, gases mix easily (left open, oxygen will rapidly diffuse into the CO2 blanket). But you should also consider turbulence.

If it helps, think about what would happen if you did all underwater in a swimming pool:
Let's pretend for a second that he CO2 in the headspace is represented by plain water. And the swimming pool is filled with milk. Now imagine what would happen if you opened the fermenter underwater. Would you expect the fermenter to stay filled with 'just' water, or would you expect some milk to get in and mix with the water due to turbulence/water currents as you lifted the lid? I'd expect a lot of milk to get in, and in the same method, a lot of air to get into your fermenter.

Let's look at what happens if you just lift up the lid on your fermenter:

As you lift the lid (green arrow), it pushes the air on top out of the way. This causes suction underneath the lid, which sucks the CO2 up (blue arrow from the headspace, causing a low pressure area. Air from the atmosphere is sucked into this low pressure area (red arrow), and turbulence mixes it with the CO2 in the headspace.

A better way of doing it would be to crack the lid, and slide it off. There will still be mixing, but less of it.

Those with narrow-necked fermentation vessels will have less mixing due to the smaller opening, which results in less suck-back of air and less turbulence

 

[buddsy]

I do understand what you are saying but we are talking about unscrewing the lid on a fermzilla.

Besides people have fermented in open vats for many years.

buddsy

 

[Agentgonzo]

I do understand what you are saying but we are talking about unscrewing the lid on a fermzilla.

Besides people have fermented in open vats for many years.

. Just wanting people to understand what happens.
I don't think that oxygen is the big boogeyman that it's made out to be. People have been pouring fermented beer into oxygen-containing barrels for many many years too.

 

[LeeH]

I do understand what you are saying but we are talking about unscrewing the lid on a fermzilla.

Besides people have fermented in open vats for many years.

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buddsy

Black sheep still do and make great beers. The public even stand above them.

 

[Brewelder]

I do appreciate all the advice lads and i do understand how gases work as I’ve worked with them all my working life, but after having 2 failed attempts at brewing NEIPA’s, even after taking all the necessary precautions, i still had “spoiled” results. Having said that i didn’t have the Fermzilla back then.

I just thought there would be an easy way to take a gravity sample without having to open the lid. Seems like the easiest solution is to draw a sample via a party tap connected to the liquid out post, or in my case a concocted tap as i don’t have one yet and this is probably how i will do it.

 

[Mayor of Simpleton]

For what it's worth, I bought my Fermzilla all rounder to improve my NEIPAs. I ferment mine at about 2 psi and take samples via a party tap on the liquid out post as you describe (if I don't use my ispindel). With that and completely closed transfers, I improved my NEIPAs massively. In particular, the fresh taste is retained for much longer.