Creeper and Evaporation

Hey all,
Some of you may be familiar with my post in the Support section asking about creeper evaporation.
I've been doing some tests and discovered that the creeper evaporates if the interval is long enough and the creeper intensity is low enough.
The emitter needs to be a few levels above the target area to hit (base level is 2 and emitter level is 5 in my map) and has to have a certain surface area (in the terrain editor I used the sqaure brush, selecting the "3" count for how big the brush is. I center the emitter on the tower and occasionally add crazonium walls to control the flow (I do not know if this affects the creeper output/evaporation effect)
To illustrate my point, I threw together a map to help you see what I mean and will attach it here (note: This map is intended solely for examination, NOT for gameplay or future submission to the CW1 custom map database).

Has anyone used this in a custom map?
I'm planning on making a map based around these mechanics, i've been trying to figure out a way to make it work in a custom map.