brewing at home

I believe that any time you pour a carbonated beverage between containers, you lose some of the carbonation because CO2 escapes. Pouring a carbonated beverage through a regular sieve causes CO2 to escape even more, and pouring it through a mesh sieve (at least it looks like a mesh sieve in the picture) will cause even more loss of carbonation.

So I would say yes, you are losing carbonation by using that sieve. If it's to filter out the fruits and what ever is in the kombucha, I would just do my best to have larger chunks that would fit through a regular wide holed sieve.

I count my F1 containers as 1 batch each. But I have heard of people counting their F2's as batches, since from 1 container of F1 they could make 4 different F2 flavors, each their own "batch".

I count each F1 as a batch. I usually have 2-3 F1s going at the same time, I count each of them as a batch, so that's 2-3 batches at once.

I am in the middle of my F2, some are natural flavor and some are flavored with fruit or herbs, I decided to lay them all down because I read somewhere that it helps with potential carbonation leaks, and I can tell you that none of them carbonated. They were more fizzy after the initial F1 than they are now after F2.

Though, to be fair, I left them for just 2-3 days for F2, and while it has been HOT here, my F1 is at 83 degrees constantly, maybe I should have left them longer, so I am standing them up now and going to give them a few more days.

That's my experience with laying them down, it would be interesting to know how this goes for others, maybe it just takes longer when they are laid down vs stood up?