Thanks for all the ideas, they are very interesting.
I'm thinking the main problem is not the gravel vac itself, but the tank. The shape of it combined with the fact that I have quite a lot of plants, doesn't give me much room to work with. I can use the gravel vac to lower the water level by about 2 inches. After that, the top of the vac is no longer submerged which doesn't allow for any more water to come out.
I have pipettes that I've been using to put water into test tubes. I tried using one to pick up the poo but it just doesn't work. I may give a turkey baster a try next.
Originally Posted by vaygirl
What's the diameter on the vac? I have one that's an inch diameter and I use that for all my tanks. It works really well on the small ones.
It's about 3/4 of an inch in diameter.