I understand the majority of the beneficial bacteria live in the filter system but some live in the gravel/substrate. Say I had a established 20 gallon tank with fish and everything. And i had a spare 20 gallon tank that's empty. What if I were to slowly (to keep water clear) siphon the water into the empty tank, catch the fish and transfer them. Pick up ornaments and decorations and transfer them and the fake plants, heater filter basically EVERYTHING BESIDES THE GRAVEL. Then empty the gravel in a wheelbarrow and fill it up with hose water. Then rinse the tank and sponge clean it and dry it then put it aside. Then go back to the gravel in the wheelbarrow and stir it up then dump water and fill again stir and dump again and again without losing gravel to clean the poop and possible left over food and whatever else. Then put the really clean gravel back in. Then the fake plants and decorations and the water and fish, filter and heater back. What if I did that every year or 6 months? The gravel gets completely clean but bacteria on the plants and ornaments and in the water go right back in? I feel like it would be ok but I'm here asking more knowledgeable and experienced people. Thanks