Sump baffles: Over/under or under/over

[dugthefish]

Setting up a new sump, using a 40L and an EMS baffle kit.

Regarding the last baffle set between skimmer chamber and return pump, as title states, what is better configuration? O/U or U/O?

I've been, and very well may continue, using a coarse sponge as a bubble trap in my existing sump. I have found that if I don't clean this sponge 2-3 times a week, the skimmer chamber water level begins to run high and messes up my skim.

 

[Peace River]

Setting up a new sump, using a 40L and an EMS baffle kit.

Regarding the last baffle set between skimmer chamber and return pump, as title states, what is better configuration? O/U or U/O?

I've been, and very well may continue, using a coarse sponge as a bubble trap in my existing sump. I have found that if I don't clean this sponge 2-3 times a week, the skimmer chamber water level begins to run high and messes up my skim.

I would go O/U and continue using the sponge. Good luck!

 

[ca1ore]

I prefer over as the final baffle. If over-under-over isn’t possible in your application, then I’d do under-over.

 

[Brett S]

Over is definitely best as the last baffle because the pump pulls from the bottom, so if you have an under baffle last it just puts all the water (as well as any remaining micro bubbles) right at the pump intake.

Additionally over is best for the first baffle. If you don’t have an over baffle to start with the top of the water level in the fuge or skimmer chamber or whatever is before that baffle will become very stagnant and oil and junk will start to build up on the water surface. The over baffle provides surface skimming for that chamber and keeps the water surface clean.

So, based on the above you definitely want over, under, over.