3 replies to this topic

[CoolColJ]

I noticed that in some of my test tube setups, the cotton wool dam moves back as the water drains, and in others the cotton does not move, and you see the water area decrease in size as the water goes down.

So one has a vaccum of sorts I assume, and the other does not.

 

Why the difference?

 

The only thing different I did with the ones that do move back, was not to push the cotton dam all the way down to water level.

I left a few mm from top of cotton to water level.

But not all

 

 

I prefer that the cotton did not move, a lot easier to tell how much water is left.

And it also does not mess with some of my cotton wool chamber setups.

Nor cause light to enter test tubes that have red cellophane around them, when a gap is formed as the cotton moves back....

 

Plus in one test tube I stacked two cotton wool dams, but only the inner one moved as the water drained, leaving a gap between the two now!

I fear the outer one will dry out sooner or later

Edited by CoolColJ, May 21 2018 - 5:38 PM.

[Shifty189]

I have far less experience with ant keeping in General, but I was also wondering about this.

It looks to me like the cotton will move if I quickly pushed it into the water, and was able to avoid making bubbles during set up. In other words if I set up the tube without bubbles that tube will tend to never get bubbles (cotton moves)

[drtrmiller]

You are correct that vacuum forces are responsible for this effect.  The strength of the vacuum is based upon how tightly the cotton is compressed when being inserted into the tube.  A looser cotton stuffing will allow air to enter and displace any liquid which has evaporated.  Therefore, if you don't want your cotton to move, compress the cotton slightly less tightly, so that small air bubbles are immediately observable as the water wicks into the cotton upon first setting it up.

 

A note of caution: do not allow the cotton to be too loose, or liquid may be more likely to drain out.  This all must be done by feel—it is a very difficult thing to measure or to precisely describe the execution. So just attempt it and make adjustments if the desired results are not observed.

Edited by drtrmiller, May 21 2018 - 5:51 PM.

[StayLoki]

@CoolColJ
I noticed the same, and it certainly has to do with some sort of vacuum.
Unlike you, I prefer the water chamber moves down, allowing for more room and drying up which is helpful for getting them to move into new humid attached tube.

The difference has to do with soaking the cotton. If you plunge it down quickly and completely submerge it, it will not move.( I suggest you 'pour out' any excess water before adding your queen, and taking a dry qtip and wicking up any flooded water if you do it this way).

If you want the cotton plug to move, push it down quickly enough to touch the water miniscus, then slowly slowly push it down and stop when the water is just about to wick out.