[Picklee]

I understand why you want to do a complete water change and scrub everything down. But I must caution you, your fish may not enjoy their clean home as much as you might. I've written an article on cleaning out fish tanks that you might find useful: http://www.helium.com/tm/174139/after-approximately-month-month.
Most don't even feel comfortable doing that. You do not and should not completely clean your plants or gravel. Note--I do mention throwing your plastic decor through a dishwasher cycle, but that's only if you have snails or a really bad algae problem. I would recommend just taking the decor out and setting it aside, they usually harbor tons of good bacteria that you will need and it would be counter-productive to wash them anyway. If it's the gravel that looks dirty to you and is bothering you, then you might want to consider getting a gravel vacuum to suck up all the debris that your tank cannot handle, and perform a small water change. I would strong suggest not to take any action past a 40% water change. Anything more could be quite counter-productive and you will have to cycle your tank for a couple months to restock your bacteria levels before it's truly safe to reintroduce your fish. Vacuum the gravel a little and in the process make a 40% water change. That's it.

 

[Picklee]

Heh, has that happened to you in the past?

I was just thinking, soap is just as harmful as vinegar, even to the bacteria. I've learned though many chemistry labs that bases can be just as harmful as acids (and they both itch). And both acids and bases can be equally harmful to the fish. So soap would work just as effective as vinegar, and either one is probably somehow going to raise or lower the pH of the new water.

 

[Picklee]

I agree, there should be no point to clean the entire fish tank in the first place.

 

[Picklee]

Hm, I always thought that the fish died of suffocation because there wasn't enough oxygen entering their bloodstream, not because this slime covered their gills. Naturally, the nitrogens in ammonia, nitrates and nitrites would rather bond with the oxygen than the hydrogens thus limiting the amount of oxygen in the blood and in the end, suffocating the fish.