Hmmm, I bought an Eheim 2217 aff of Amazon for about $140 after shipping. It has shutoff valves on both the tank hoses and the canister hoses, so that no water goes spraying when you disconnect it. Then you just take it to you bathtub or whatever to release the pressure before opening it. So easy.
Here's what I do when taking down my canisters for maintenance:
1. Turn off inlet valve
2. Wait a few seconds
3. Turn off outlet valve
4. Immediately turn off power
5. Remove quick disconnects
6. Turn filter upside down over a bucket to drain some of the water out
7. Open it up
This works like a charm. Sequentially turning off the input before the output lets the filter purge a little extra water so it doesn't spurt out when you remove the quick disconnects.
