Newbie Question: Durso Overflow

[r33fermaddness]

This may be a brainless question to some, however I’m fairly new to this and had some queries regarding overflow weirs with Durso standpipes.

Example:

My current project: 90g secondhand tank. Still needs a lot of cleaning, and I have a replacement top frame on the way.
Anyway, the back left corner has an overflow weir with holes drilled on the bottom for drain and return plumbing. (In this picture the Durso pipe was not inserted into the bulkhead.)

Excuse the dirtiness, I still have yet to scrub the inside and cover of the overflow.
So to my understanding, once everything is up and running, as water flows through the teeth into the overflow, it will then be sucked into the durso pipe and down to the sump.
Now my question: will water at the bottom of the overflow make its way to the surface to be drawn into the standpipe, and how so? Because how I understand it, once the overflow fills up, only water that’s freshly entered the overflow will be drawn into the Durso and I would think the water at the bottom will become stagnant until stirred upward by an outside force (ie me, purposefully doing so as part of tank maintenance.)
Maybe I’m just not grasping the whole concept of tank flow, but that was something I’ve been pondering as I go through the motions of planning the tank out.
So will the water at the bottom of the overflow eventually get recycled? Or if it doesn’t, is that something I need to worry about and add to the list of maintenance done on a regular basis?

Thanks for any info!

 

[John08007]

Too much to read, put in a herbie overflow, run return up and over the back. Super quiet, will love it. Had mine for years, never had any issues.

 

[JumboShrimp]

I “think” I understand your question. You are worried water at the bottom of the overflow will essentially stay there and stagnate. No. Won’t happen. Even the slightest water flow (caused by water falling into the overflow from the tank) will cause the water to ‘mix.’

Imagine hypothetically if you could fill the bottom third of the overflow with yellow food coloring. Do you think it would just stay there and not mix with the rest of the water and fail to eventually go into the pipe and down into the sump? No way. Hope this helps!

 

[John08007]

I have a 30" tall tank, I do get detritus at the bottom. I dropped a power head in there to mix it up and keep is suspended in the water column.

 

[JumboShrimp]

Detritus is a slightly different issue, but @John08007 has a decent solution for that. Would probably only take a very tiny powerhead.

 

[John08007]

Detritus is a slightly different issue, but @John08007 has a decent solution for that. Would probably only take a very tiny powerhead.

Yep, I have the smallest rio that they make. Probably under $20 online

 

[r33fermaddness]

Thanks, that’s the info I was after.
@John08007 do you keep that power head in there at all times or just pop it in there occasionally?

 

[John08007]

Thanks, that’s the info I was after.
@John08007 do you keep that power head in there at all times or just pop it in there occasionally?

I leave it in there all the time, occasionally plug it in to stir it up. Probably wouldn't hurt to just let it always run.

It may be a rio 90, 18.99 on amazon. Mine just dangles in there because it is too tight and tall for me to slide my hand down there to stick it onto the glass. I plug it in and pull the wire up and down some to get it all stirred up and unplug it.