I would not use gravel that has been laying around outside, as it might be contaminated with harmful chemicals like pesticides, oils, fertilizers, etc. However I frequently use bagged pea gravel bought from the local hardware store. It is very inexpensive and has a nice, natural look. But unlike the clean, prepared gravel you buy at pet stores, pea gravel will be very dirty. You must rinse and rinse and rinse it to clean it properly. Pour some in a clean bucket and rinse repeatedly with the garden hose while stirring the gravel until the water runs absolutely clear.
you have to use your hands....
Do not use gravel in a turtle tank. They will eat it and it can cause serious problemlems - even death. If you do want to use gravel it must be very large gravel so that they cannot eat it but you may also just have a bare bottom - it is easier to clean also.
of coarse if clean gravel.
All you would be doing is storing poisons in the tank for release later if there is a power out. This would result in death to the whole population in the tank. Most experienced aquarists believe that poisons should be collected and treated outside the tank in a properly cycled filter where the Ammonia is converted biologically into harmless Nitrate.
There are under the gravel filters, hang on filters and canister filters. There are also reactors that can be used for filtration. Under gravel filters are actually under the gravel in your tank and use a air pump to create suction to pull dirt and debris down into the gravel trapping it there. A gravel cleaner, sometimes referred to a gravel filter is generally a plastic tube attached to a length of hose that uses siphoning to draw dirt, debris and water out of tank into a drain or holding container to be disposed of.
Aquarium gravel is simply gravel that goes in the bottom of your aquarium. You can also use sand instead of gravel. The gravel has several purposes: It makes your tank look nice, it hides waste (which is why you should gravel vacuum once a month or so), and it provides surface area for good bacteria to live on. It comes in many colors, including brown, white, black, and neon colors.
It is best to use pea sized gravel or sand. This is safe for them to eat as it will pass through them easier than gravel which can get stuck in their digestive system.
Use a syphon, a gravel vacuum, or get a crayfish because they just eat fish feces all night long.
You use an anti-rust enamel.
If your water is acid, coral may be of use in buffering the acid since it is alkaline. Otherwise it could well be detrimental. Coral must be properly cleaned before being placed in a freshwater tank.
I would not recommend the use of gravel for a driveway as everytime you drive over it gravel is flicked about by the car tyres.
To clean debris that falls in the gravel, you should buy a gravel vacuum available at pet stores. You should use the vacuum during each weekly water change to keep the debris to a minimum and avoid making your fish sick.