AIO not necessarily water tight?

[Razorwitz]

I just picked up a JBJ Nano RL 20 and filled it last night for the first time.  I noticed that as I filled the main compartment the rear compartments filled as well, at almost the same rate.  It seems that they are not sealed from the main area.  Is this normal, or should it be more watertight?

[paulsz]

There's a hole an inch or two from the bottom, near the side with the overflow weir. Could it just be filling through that? Or is it just spilling over through the seams?

[Razorwitz]

I just noticed the holes...  I'm sure that's where it's coming from.  That's odd.  I had assumed that the back chambers were supposed to be more water tight...  I feel stupid now...

[paulsz]

all good. Same goes for the fluval evo and i'm sure alot of other AIO. People tend to plug them (i used a bit of epoxy but if you can buy a specific plug for it if you want). That way it doesn't shortcut the filtering process. 

 

I think it's meant to keep the levels stable on both sides. If you do a large waterchange, you won't have pressure from one side of the wall on the other. I think that's the reasoning for the hole. But i only do like 20% waterchanges so it's never that different between the two sides. 

[Clown79]

The water from the display needs to get into the back chambers as well as the display, it will fill from the overflow or any little filter holes in the wall.

 

The water level will not change in the back until a pump is running.