AGA overflow with Mag9 - Need help

[foxthorn]

I can't seem to get my water level correct... I've got a 90gal with the AGA built in overflow. I'm using a MAG 9.5 in the stand directly under the tank. I also have a Durso with 1.25 inch pipe down through a 1 inch bulkhead.
I'm wondering if the AGA overflow just can't handle the MAG9 at about 5 feet of head. Or is it my Durso setup that is causing the problem?
Has anyone gotten the MAG9 to flow full out on a 90 or 75 gal AGA without altering the overflow slots??
TIA

 

[foxthorn]

Good suggestion...
I took off the durso and what I noticed was that the water in the overflow chamber did not rise much. It appears that the water is just not getting into the overflow fast enough.
Any suggestions on the best way to widen the slots. I read some posts that suggested removing a few slots and another that suggested drilling 1.4 inch holes at the bottom of each slot.

 

[foxthorn]

The water inside of the corner overflow stays low - so the water is getting down the drain fast enough.
The water in the tank rises higher and higher until it is over the slots. I think I need to increase the water flow into the overflow chamber - by possibly opening the slots a little wider to increase volume of water entering.

 

[foxthorn]

I increased the width of the slots and now the slots are keeping up with the MAG9. The water flow is such that just the very top of the slots are shown - the rest is under water.
I don't think you want the water going over the overflow wall above the slots -- this would allow fish etc to fall into the overflow.
What is interesting though is the slots are somewhat tall - so the water seems to flow faster toward the bottom of the slots and thus not much surface skimming is done.
Any ideas on how to get the surface to skim better?

 

[david s]

there are slots at the bottom of the overflow also did you cover them with sand???. my slots are below the water but it does not spill over the top of the overflow

 

[david s]

hmm maybe I will pump up the volume and open that mak4 all the way up

 

[foxthorn]

Instead of gonig OVER the top of the slots what if you just made the slots wider. This way more volume of water will pass through the slots and thus lower the water level to be lower in the slots --- should create more surface skimming - right?

 

[broomer5]

foxthorn
I don't have this type of overflow - so I'm making some assumptions here.
Is it the All Glass Twin Flow design ?
The curved black partition overflow in the corner of your 90 ?
If so, I agree with you on increasing the size of the slots.
I would not mess with changing the vertical sizing - only horizontal width of the openings.
Changing the height of slots will change the level of the tankwater. Increasing the horizontal space only, would allow more water to pass through to the inner area.
From the looks of what I've seen - it appears like there's some plastic material between each slot.
I would cut out that material - basically making two slots into one longer horizontal slot.
Then skip a slot leaving it the way it is.
Then remove another plastic area between two more slots - making another longer horizontal slot.
Widen them to make them larger.
Don't make them any deeper though.
In theory then - you would increase the water flow capacity through the entire overflow - and the water level would drop somewhat in your tank. But only down to the lowest point ( lowest point of all slots ) when pump is off, and slightly above this level when pump is on.
Make each weir/slot wider - not deeper.
A small Dremel cutting tool and file might be handy.
Maybe something like this ?

 

[foxthorn]

Thanks for the ideas... I did make the slots a little wider -- I used a drill bit a little wider than the slots and opened them up a bit. (It's a standard AGA corner overflow).
Right now my slots are very close to being fully covered in water flow. So I think this has solved my original problem of getting my overflow to 'keep-up' with the pump. My MAG9 is now running wide open. But given the water level it appears that it's just keeping up with it.
My only concern now is that it doesn't seem like the surface water is flowing into the overlfow since most of the water is falling into the overflow from the _bottom_ of the slots. This whole AGA overflow slot deal seems like a bad design to me. I've added a powerhead pointed at the surface and this seems to have helped.
I'm thinking if I made the slots even wider that this would drop the water level such that more of the surface water is overflowing like it should.