langcjl
The baffles that some folks use can serve several purposes.
1)
Help to eliminate air bubbles.
As water drains down from the overflow/display tank, it basically is falling. Ever pour liquid from a pitcher into a glass ? The higher you pour from, the farther the liquid has to fall right.
When it hits the glass of liquid, it creates bubbles.
Imagine pouring a glass of ice tea, with the pitcher 4 feet above the glass. You're going to get bubbles in the glass of tea.
Same thing happens in our drainline to the sump.
Tankwater rushing down sometimes makes bubbles in the sumpwater. Not just large air bubbles you can see, but also lots of tiny bubbles you have to really look hard to notice.
In an open sump without baffles, it's likely that many of these smaller bubbles will stay in the water. They would like to rise up and pop, as bubbles do. But in a smaller sump with a return pump in it - these little bubbles get sucked back up and ride up to the display tank. When the water shoots out into the tank for the spraybar/fitting ...... so do these bubbles.
Then the tank fills with little air bubbles and that's not such a great thing.
Baffles are simply little walls or dividers, that are normally placed so as the draining tankwater hits the sumpwater, the air bubbles produced are contained in the first area. Some of them rise and pop, but some fall over to the next baffle/area.
Some bubbles rise and pop there too, but some don't.
The water carries these bubbles over to the next baffle/area.
Same thing happens ... some bubbles rise and pop, while others still move on through.
The baffles just allow the water to be forced to follow a course. This path or course allows what's called "dwell" time.
Dwell is just the length of time it takes for the water to move through the course.
Baffles don't slow down the water. So many gallons are going to race through the sump whether you have baffles or not.
The baffles just make the water go a certain way through the sump - instead of just swirling around randomly.
Making the sumpwater follow this path of up and over and up and over each baffle will give many of the tiny air bubbles a chance to rise and pop. When they pop - they're gone.
The more baffles - the more the sumpwater has to follow this path. Normally the more baffles/dividers - the less chance for air bubbles reaching the return pump at the other end of the sump.
2)
Baffles or dividers also create areas to place equipment.
You can place a protein skimmer in one area.
You can place heater(s) in another area.
You can run carbon in another area.
Dose chemicals in another area.
And so on.
3)
In a sump/refugium combo - the baffles serve as dividers as well. You can make an area in the sump to have a sandbed or live rock and grow pods/algae.
Normally the flowrate through our sumps is too high for these sump/refugiums to work efficiently. Some people can do it - they just have to modify the flow path so all of the tankwater is not rushing through the area containing the sandbed.
You don't need baffles - I don't use them right now. I just have an el cheapo rubbermaid sump.
When I re-do my sump someday in acrylic - I plan on installing baffles for sure.
