Ok, this is one of my favorite things I built for this tank. I pull out about 1 1/2 to 2 gallons a day from my skimmer, so the standard collection cups just don't cut it for me. So I came up with this DIY collection cup that works great, took less than an hour to build and costs all of about $15 or $20.
It consists of a
five gallon bucket with a toilet flush valve mounted upside down in the lid.
Top view when full (Flush valve closed)
The flush valve closes (which shuts down the skimmer) while the skimate level is still 4 or 5 inches down in the bucket which makes disposal easy.
Skimmer when cup is full
Flush valve when cup is not full
Flush valve assembly. The foam provides more than enough floatation to clamp the float shut very tight.
The chain prevents the flapper from swinging to far
I used silicon to plug the flush valve standpipe. This is necessary so that there is back pressure on the skimmer when the cup is full. The cup must be air-tight when it is full.
It's just a tad bigger. 
