@MattDMo I know that. And this is how I do this - I expect people to learn something. But this guy is careless, he doesn't listen properly, then thinks he knows things better and can improve them by himself etc. Really annoying.

Especially the last thing. It is ok to think about why we do things, but for some there are clear reasons. And if you don't even ask why we do things in a certain way, but want to change them immediately it gets difficult. And if he doesn't change that, I am going to kick him out of the cell culture room where I am responsible for. Before we all get his frequent contaminations.

@Chris Let him do what he wants. He'll only end up ruining his own experiments. As a lab incharge, issue him restricted amount of reagents.

If it is a central cell culture room then you should impose restrictions. Allowing too many people always creates a mess.

@WYSIWYG I do that. He is not one of "our" students where I would care more (and who have learned to listen :-) ), so he can do that. It only costs some money, but ok.

And I make very sure that he is not going to affect other people.

we basically have 2 cell culture rooms with 2 hoods in each. Not optimal, but ok.

@Chris but you (or someone from your lab) are the one who provides media and other reagents to him, right. Just don't give him anything unless he follows instructions :D

And when he gets back to his "own" lab he can do whatever he wants to do.

We don't handle it that strict with the reagents, since usually people know what they do. And it takes too much time to do that.

The dangerous stuff (toxins and so on) is of course locked up - but this is a safety requirement.

I used to be in charge of our lab's cell culture room once.

I used to prepare media (the powder one) for everyone and co-ordinate cleaning activities.

I do the ordering anyway, so I have an overview of what we have and need. And luckily we order ready to use media for cell culture.

So we had a sheet where you have to enter how much media is spent. I used to reserve my share and if anyone is wasting stuff, they won't get any more.

Media on the other hand is not really expensive. There are other things like the westerns and the gels which really add up. Or the extensive usage of some kits.

Powder media has a longer shelf life. We have a stupid bureaucracy: the money (to the institute) would be provided in bulk and if it is not spent in some time, then the remainder is taken back.

So people do bulk orderings. Or you should hire a good accountant to handle these expenditures in a way so that you have constant supply throughout the year.

The first options seems easier for most people (plus the accounts handling has to be done at the institute level).

I often find that people order too much stuff in anticipation and they get expired.

You're right. But since we also put in our work time (at least when we argued against it :-) ), it doesn't make a real difference.

the problem with the spending is the same everywhere. If we don't finish it by the end of the year, it'S gone. And this will of course not happen.

So we order quite a lot of stuff by the end of the year and our storage is full.

@Chris OK, that's a different situation than I was imagining. In that case, feel free to rule with an iron fist. I welcome discussions from people about why we do things the way we do, and if there are places where it's OK to have a personal preference, what the possible options are that still get the same, high-quality results. But taking it upon yourself to change things just because you feel like it, or are lazy, or whatever, is no good.

And if it results in contamination, boot him now. Your work and time is too important.

Doesn't premade media last at least a year if it's kept from light?

@MattDMo I'll take the time to explain stuff and show people how to do things when they listen and obviously learn something from it. This is important and that's how I learned the stuff. So I hand it on...

@MattDMo Yup, exactly. And not only me...

@MattDMo Depends on the media. Most are pretty stable (except for glutamin) and can even be used after expiry. As long as they are not cloudy :-)

@Chris I usually try to use a separate container of GlutaMAX if possible. It's really cool stuff.

@MattDMo We use so much media, that it is easier for us to use the one which is ready to use. Additionally it is one item less which needs to be ordered and which people use up without giving notice some time ahead.

That's true. Some media comes with GlutaMAX already in it - DMEM, RPMI, Ham's F12, DMEM/F12, MEM, IMDM, Opti-MEM... so maybe you could check that out. On the other hand, it's not necessarily a good idea to switch media in the middle of a study, because who knows what is affecting your process of interest.

I completely sympathize with running out of stuff because no one said anything. I was halfway through splitting a bunch of flasks one day when I noticed there was zero trypsin left. Fortunately someone had received a sample of a couple of bottles of a new kind that can be stored at RT, so I stole that :)

Here it is - TrypLE Express. It's about twice as much as their regular Trypsin-EDTA.

@MattDMo We basically use either DMEM or RPMI for most of our cells. Sometimes a bit more obscure melanocyte media for primary cell culture, but thats basically it.

@MattDMo And it's not even much work. They simply need to notify me or write it down in our order list and I take care of it. But I shouldn't complain too much here, since it got much better in the last month. But it happened once or twice that people had no reagents.