How low to Mount overflow

[guggas]

I'm about to drill the back of my tank to mount an overflow box. My tank trim comes 1" down the glass as you can see in the pic. The teeth on my overflow are also 1" tall. I was thinking I would mount the top of my overflow teeth 1/2" above the bottom of my trim and 1/2" below the top of my tank glass. I would keep my water level about 1/8" below the top of my teeth and that would be 3/8" above the bottom of my tank trim to hide the waterline. Does this sound right or are there any guidelines to this?

[Bc chick]

Hmmm no pic😕

[guggas]

100684100685

[rickztahone]

That looks way too low to me. Keep in mind, the water line will be at the BOTTOM of the slots (teeth)

[LostSouth]

I have a rimless tank and the top of the overflow is a half inch below the top. You want to leave enough for the water to be able to go over the top of the weir gets clogged.

[Neptune]

I don't have teeth on my weir but it is even with the bottom of the trim. This leaves me about 1 inch of safety.

[diegote]

IMO the jump shouldn't be too tall (bottom of the teeth vs level behind the weir), otherwise it can be noisy

[Neptune]

Also do your research, you don't want to cut your holes to close to edges so they crack. I forget what the minimum distance from edges but be sure to check.

[guggas]

Thanks for the feedback guys. I found this calculator posted on reefcentral: http://irrigation.wsu.edu/Content/Calculators/Water-Measurements/Rectangular-Contracted-Weir.php I've been playing with it some to see how much my proposed flow rate will raise the water level above my weir. I think I have a handle on it. I'll post back my results once I get it drilled and tested.

[guggas]

That looks way too low to me. Keep in mind, the water line will be at the BOTTOM of the slots (teeth)

Rick, I think my water level will have to rise over the bottom of my teeth some because my overflow is kinda small compared to my flow rate. I probably should have gotten a bigger one, but I think it will still work. Your overflow is really long compared to your tank, almost coast to coast, probably why you water level is at the bottom of your teeth.

[rickztahone]

Rick, I think my water level will have to rise over the bottom of my teeth some because my overflow is kinda small compared to my flow rate. I probably should have gotten a bigger one, but I think it will still work. Your overflow is really long compared to your tank, almost coast to coast, probably why you water level is at the bottom of your teeth.

I actually don't have "teeth" on my overflow. I didn't want the restriction of only getting half the overflow.

With that said, I accounted for water rise when I made my calculations. If I remember correctly, the water only rises less than 1/4"

[Neptune]

I have less flow rate on my pump, so I only get about an 1/8 going over my weir.

Just curious, how are you going to plumb this. Straight to the sump? External over flow box?

[guggas]

I have less flow rate on my pump, so I only get about an 1/8 going over my weir.

Just curious, how are you going to plumb this. Straight to the sump? External over flow box?

I'm not 100% sure if I'm using the correct terminology but: I have that internal over flow box with two 1" bulkheads in the back. I'm going to drill two holes in the back of my tank for the bulkheads. That will attach to a larger external box with three bulkheads in the bottom. I'm going to do what I think is somewhere between a bean animal and a Herbie. Basically a Herbie but with three drains. One full siphon 1" pvc, 1 trickle drain pipe and one completely empty emergency drain. I'll put some pics up when I make some progress, I'm moving kinda slow due to a needy job, wife and kids.

[Neptune]

I'm not 100% sure if I'm using the correct terminology but: I have that internal over flow box with two 1" bulkheads in the back. I'm going to drill two holes in the back of my tank for the bulkheads. That will attach to a larger external box with three bulkheads in the bottom. I'm going to do what I think is somewhere between a bean animal and a Herbie. Basically a Herbie but with three drains. One full siphon 1" pvc, 1 trickle drain pipe and one completely empty emergency drain. I'll put some pics up when I make some progress, I'm moving kinda slow due to a needy job, wife and kids.
That is EXACTLY how I have mine setup. LOVE IT!