I just like using hot water, hot fresh water. The filtration components, the decorations, after awhile, their going to get really scummy and nasty, and they are going to need some cleaning. Take them out, use strong, hot water. You want to use a brush that's not going to gouge the filtration, just use an algae cleaning brush, or a sponge. You don't want to use a sponge that's intended for household use, a lot of them have antimicrobial agents and when you put it back in the aquarium, those antimicrobial agents are going to kill the bacteria in the system and result in a pneumonia or nitrate spike so never use household sponges, always use an aquarium sponge, or even a terry cloth, or paper towels works fine, just not a regular household or kitchen or dish sponge.
You just want to use hot water, it's common sense. You don't want to get soap. Make sure you rinse everything really, really well just in case you did spray some soap on it if it was in the sink and you just washed dishes in there. So, that's how you take care of your filtration components but as far as the decorations, you also want to use hot water.
I like to sometimes use a little bit of bleach, be very careful with bleach because bleach will discolor a lot of things. If you find that dark green algae has grown on your plastic plants, sometimes the only way to get them back to their original condition is to use a light bleach solution. What I do is I put the plants in a five gallon bucket filled up with hot water, and I just put like one or two cap full of bleach in there and I leave it for 20 or 30 minutes, stir it with a stick a couple times, you can pull the plants out and see if the green algae has gotten off of it. If it hasn't and the color still looks good on the plants itself, you can add a little bit more bleach, but I'm warning you right now, if you use too much bleach, your plants could turn clear or white. If you have salt water decorations, like bleached shells or coral and its got a lot of algae on it, you can use a light bleach solution too, a couple of cap fulls to a five gallon bucket with hot water, just soak the corals in there for an hour or so until they're nice and clean and then rinse them with hot water, put them in the sunlight for a couple of days. That's the best way to do it.
You do run the risk, if you take the corals out of the bucket, rinse them, and put them back in the aquarium, you run the risk of putting bleach in the water and chlorine, and it's toxic to the tank. When you put the decorations back in that has been bleached, use a good decholorinator, stress code or anything with sodium biosulfate, that's the main ingredient you want to look for, that's going to neutralize a lot of the chlorine and chlorinates. If you let the items air dry for a couple days, preferably in the sun, you're pretty much scot free, you're fine.