Two DIY projects that are easy
recently I have completed two projects, the first is coconut houses and the second was to increase the suction power of a regular tank vac and to give the tank vac some surgical precision so I don't vacuum up baby shrimp.
take a small coconut and drill three holes in the top and drain the milk, then cut in half and take the meat out. next take a pair of diagonal cutters and cut your door in the bottom of the half that has the holes in it. Let the shell dry for a week and put into your tank. This will give surface area for bacteria to grow, a place to anchor moss if you want and breeding or hiding holes for your fish and critters that like to hide (Khuli loaches and freshwater shrimp in my case). I used two coconuts one for the tank with Kulis and the other for the shrimp tank.
I wanted to be able to suck up more pond shrimp so I got a piece of clear rigid tubing that would fit the flexible clear tubing of the tank vac, took the 2 1/2 inch rigid vacuum piece off and replaced with the smaller diameter rigid tubing (tubing has to fit tight into the flexible tubing, I used maybe 1/2 inch diameter rigid tubing and cut to the length I wanted.) This has enough suction to suck up gravel so I have to be careful, but it easily sucks up snails.