Cleaning 10% and its after effects

Yes, just the way you clean your home, the fish tank needs cleaning ... removal of food decay and daily wastes. We bought small gravel vacuum, by Topfin. It is easy to us. The first time we did it, it was interesting to see the changes in the fish tank after cleaning. Here are a few steps:

• Turned off the filter and heater and of course the light! 
• Introduced the cleaning pipe, which works mainly using the principle of siphonage. 
• Placed a large container and emptied about 10%-15% of the water. Food particles were scattered all over the place. Removed a terracotta ornament that we had placed in there, and thought the Tetras wont miss it! 

Oh boy! As soon as we were done with the cleaning, tetras were breathing hard, and swimming frantically. They were hitting the glass surface and the place where we had the terracotta piece, they collectively stood there starring at us from inside!