In the back left (actually left side of the tank) I have the AC filter and a limewood airstone under the outflow diffusing diy co2. Works good, get bubbling at the end of the day but im sure i dont get 100% not even 80% diffusion.
thats a really good price. I was lucky to skip on shipping and got them 6 for $6. I would really suggest these to anyone with a 10g tank or even a 20-30g.. getting a school of 20 would be so hot!!