A couple of questiosn reguarding changing substrate....

1) I would take everything out and remove what you can of the gravel (don't kill yourself to get it all btw).
- 1.a) Place the fish in a rubber barrel w/ your old tank water - just add an air line and heater and they should be okay for a quite a while.
- 1.b) Remember sand will take a LONG time top settle down...

2-3) Possibly, but I would wait a week or two after a filter maintenance and test often! They worse case is a WC.

if you have a lot of decorations and well established filter media you should hopefully be able to avoid the mini cycle. dont 'wash' any of our stuff after you take it out of your tank

Don't forget to keep your filter media wet during the process as well! I just did this a couple of months ago and it really wasn't as difficult as I thought it was going to be. Not difficult, just a bit time consuming. Good luck!

Time consuming, smelly and messy!. I'd suction the gravel as much as possible before starting too. The less fish poop you need to sift through the better. Don't try to get it all out. Spread whats left thinly across the bottom and add your (well-rinced) new gravel. Unless you are switching from bright blue to black, you shouldn't be able to tell that you ever changed the gravel out.

1. Put fish in a bucket with tank water (if you think it might tank a long time or water temp might drop add a heater and thermomenter, check temp often).

2. Put tank decor and filter media in another bucket with tank water to keep wet.

3. Empty tank and start scooping. Ditto on not breaking your back to get every little pebble. You'll probably never even see the handful that's left in the tank.

4. You might want to rinse out all the sand before you start messing with the tank itself to avoid leaving the fish and everything in the buckets for too long. Then you just have to dump it in and refill. Make sure to rinse it really, really well to avoid clouding/silt deposits on everything. In the long run, it's much less hassle.

5. It might cause a little cycle, depends on how much bio media you've got in the filter, etc. You could pick up a bottle of Tetra SafeStart (formerly BioSpira) to prevent it if you want. You might have to ask for it as some places keep in in the refridgerator in back (can be shelf stable but lasts longer when refridgerated).