That's the pump that does not come with a controller correct? What are the air stones for? Did you say and I missed it. Were you using a dosing pump before? I have a bio cube 29 too and am struggling with keeping calcium up. I was gonna do kalk in ato but heard its not great for smaller tanks. Also thought about calcium reactor but I don't have a controller (apex) yet so wasn't sure how It would work. I currently dose manually and it's too much trouble.