Overflow Teeth

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lilredwuck

Guest
I have built my overflow, 16x6x4? Something of that nature. I have (2) 1.5" bulkheads for drainage. Dead center, next to each other. 90 gallon tank. Wondering what size teeth, the spacing, how far down to cut to achieve the right flow. Doesn't need to be exact, but a starting point would work wonders.
 
spanko

spanko

Active Member
In my reading the surface area of the teeth openings should equal to or greater than the surface area of the drain.
A 1.5" circle has a radius of .75"
The surface area of a 1.5" hole therefore is 2.355" and the total opening area of your teeth would be eqaul to or a little greater than that.
That is kind of a simple example not really using any of your dimensions but I hope you get the idea.
 
scsinet

scsinet

Active Member
I use a 1/4" router bit and move the fence on the router table 3/4" to move from one tooth to the next, so my teeth openings are 1/4" wide, and there is a 1/2" space between them. That's what I found to be about the least I can do in 1/4" acrylic without worrying about breaking teeth while building the overflow or when using it.
I usually cut to about 1 to 1.25 inches deep.
I don't know what flow rate you are trying to achieve, but I just did one with (2) 1.5" bulkheads like yours using a 12" x 2" overflow box and was able to run a huge amount of water though it, so I don't think you'll have a problem if you used those figures.
 
veni vidi vici

veni vidi vici

Active Member
Teeth arent even necessary.I built a coast to coast on my tank with no teeth.The overflow is only going to take on as much water as is being returned.

Just have eggcrate over the top to keep out snails and fish.
 
E

eric b 125

Guest
hey VVV, what type of silicone did you use on that? ge type I? the other day when i was at the depot for plumbing and sump stuff i called the information # on the back of ge type I and the lady said it is not safe for aquariums. even though i knew some experienced people on here that have used it, it got me second guessing so rather than spending $5 on a tube of that i spent $28 on Lux.
 
veni vidi vici

veni vidi vici

Active Member
Originally Posted by Eric B 125
http:///forum/post/3199179
hey VVV, what type of silicone did you use on that? ge type I? the other day when i was at the depot for plumbing and sump stuff i called the information # on the back of ge type I and the lady said it is not safe for aquariums. even though i knew some experienced people on here that have used it, it got me second guessing so rather than spending $5 on a tube of that i spent $28 on Lux.
I dont remember,it was 100% pure silicone without the mold and mildew resistant chems in it. I think Type I ill have to look into my build thread.
 
scsinet

scsinet

Active Member
It's a libability issue... the manufacturer doesn't want a tank to fail using it and get sued.
But GE Silicon I Window & Door is the stuff to use.
 
L

lilredwuck

Guest
where about might I mount this thing to get the correct water level. I have an inch of plastic on top, until it hits the lip of the plastic that holds the lids. Once it's mounted it'll be kind of hard to redrill higher holes. LOL
 
scsinet

scsinet

Active Member
You definitely want the water level to be above the plastic, so you don't see the waterline.
If you are building a toothless overflow, I'd mount the top edge about 1/8" to 1/4" above the plastic lip. If you are building a toothed overflow, I'd mount the top edge of the box about 1/4" below the top edge of the tank.
When in operation, water will rise above the bottom of the toothed openings or above the top edge of a toothless overflow to some extent. How much so will be determined by the flow rate, so you want to account for this, but you also want to make sure the waterline is higher than the plastic top frame of the tank.
 
L

lilredwuck

Guest
As I have found out everything is so technical! Better to get it right the first time though huh?
 
L

lilredwuck

Guest
I made my box and am needing a needle applicator to assemble. Teeth on 3 sides 1" deep and 1/4 apart and wide. I think I cut it a little close or off somehow, remember 20 numbers and cutting days later didn't help anything. The top of the box sits flush with the bottom of the plastic lip.....BOOOO.... I guess I have to make a new box, but cutting out the teeth sucked, as I used a 12" miter box. Scary and dangerous!!! (Do not attempt)
 
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