# possible overflow design? what do you think



## jzon414 (Nov 1, 2009)

ok so im new to the auquarium world here, so i really have no idea what im talking about here but bear with me... iv been reading up on here about how to set up a tank. im getting a 105Gal tank from a buddy and i want to make it a salt tank. obviously i want as little in the tank (equipment wise) as possible. its a non drilled tank, and i really dont want a hang on overflow to be seen in the tank. so i was thinking about how to do it with as little showing as possible. once again i dont know what im doing for sure so if its a stupid ass idea dont hesitate to tell me that. or if this has already been done, but i havent seen it 


k so here it is...

i want to take the tank to a glass shop and have them drill 2 holes on the back wall, in the top left and top right corners. install a bulkhead grommet in each and run them (with PVC) to the sump along the back. the red in the pic is the pressure/return pipe, purple is suction/ sump feed. i would keep both holes up high in case of power outage/pump failure. the dark blue shows normal operating water level, and the light blue shows theoretical level of each tank in the event of a failure. the yellow and red thing on the pic is a ball valve to maybe control the sump feed flow so as to not overfill or put more water in the sump then the pump is taking out.

please look and let me know your oppinions on why this will/wont work. thank you


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## nfored (Mar 31, 2008)

It should work, however be 100% sure its not tempered before taking it to the glass shop. If they don't check or can't tell its tempered and they put the drill on there, good bye tank.

The drain will need to be able to flow more then the return, and because its a horizontal overflow it will flow slower then the same sized vertical overflow. in your sketch you mention a ball valve so the sump doesn't fill faster then it drains. This is the opposite of what you want if that happens the sump will run dry, you can never ever match the flow of drain and pump the flow changes over time. The goal is to drain way more then you can pump out. As long as the sump can hold all the water you drain out your in good shape. This is controlled by how high or low you set the drain intake. 

Also you will need a check valve on the return, if its lower then the drain, otherwise when the power/pump stop it will siphon back into the sump.


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## jzon414 (Nov 1, 2009)

i dont think it can be tempered at this point cuz it has a chip in it already and survived so.... and the return would be at the same level as the drain, the first picture just doesnt show that, but either way should have a check valve in it anyways though.

and what do you mean cuz its a horizontal overvlow? what would make it a vertical one? cuz its only horizontal at the point where it comes out of the tank which i would think would be the case with any overflow


EDIT** unless yout talking about a hole drilled in the bottom of tank right? if thats the case would it be better to build a corner overflow box and have the bottom drilled for thte drain?


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## willieturnip (Aug 30, 2009)

Tempered glass can chip and still maintain integrity. How deep is the chip? 

The reason that tempered glass shatters with so much energy is in it's making.

They heat the glass to about 1400 degrees IIRC, then cool it very rapidly. This toughens (and also shrinks, which is the key to the problem) the outside of the glass faster than the inside. The inner glass is then restricted in growth and this creates huge pressure, which in turn creates the "explosion".

If it's a shallow chip the strength of the glass is still enough to hold the pressure, which is why a chip cannot reveal if glass is tempered or not.


It's hugely likely that the base is tempered and the sides, back and front are not. But why take the risk?

There might be a tiny mark somewhere to indicate the glass type. It's a requirement that they mark tempered glass when it's made (sensible health and safety for once!) but often it's just a sticker that gets removed (silly)..



Edit: Also, this is very similar to the drilling on my 150. Though I only have the one hole for an overflow. I couldn't see the advantage for a hole for return..


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## jzon414 (Nov 1, 2009)

this is a pic of the chip. its kinda deep... the chip is on the front glass. its about 1-1.5 inches tall, and maybe 1/4 wide (it exposes about half of the side glass and i think its 1/2 inch glass)


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## nfored (Mar 31, 2008)

jzon414 said:


> i dont think it can be tempered at this point cuz it has a chip in it already and survived so.... and the return would be at the same level as the drain, the first picture just doesnt show that, but either way should have a check valve in it anyways though.
> 
> and what do you mean cuz its a horizontal overvlow? what would make it a vertical one? cuz its only horizontal at the point where it comes out of the tank which i would think would be the case with any overflow
> 
> ...



Yes bottom drilled means vertical, which has faster flow rate; this is not important if you plan for it, I like horizontal overflows and make them on all my tanks, they are quieter and safer. If my overflow fails I lose 5 inches of water out of 25 at the most. If a bottom overflow fails you loose 25 inches of water. The reason vertical is faster is the flow is aided by gravity, the whole time. Where as a horizontal its only aided by gravity after it leaves the tank, it still has to flow sideways to exit the tank.

If the return and drain are the same height a check valve on the return only adds restriction and no safety. 

Another nice part about horizontal is if you design it right you can change it to be a drain for water changes. For example when I want to change the water I used to just turn the 90 degree elbow so instead of facing up at the top of the tank it faced the bottom, I then added the proper length of pipe. this would drain the tank to that level very easy. 

Since then I have drilled a dedicated water drain just for water changes, and placed a ball valve on it, now my water change is consist of truning two ball valves. I turn the first one go get a snack come back and the tank is drained to the proper level, I close that valve and open the one that adds new water to the from the houses water main.


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## willieturnip (Aug 30, 2009)

Fill it outside and leave it for at least 24 hours.

Thats a seriously big chip. I would be worried about how structurally sound the tank is..


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## jzon414 (Nov 1, 2009)

nfored - thx for the info, and i like the water change idea

willieturnip - im not worried about that too much because its my friends current tank. it is full and running right now. he just wants a bigger one so when he buys it, ill buy his. so like i said im not worried about it leaking or anything, and im thinking that with the tank surviving a crack like that its probably not tempered.


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## wake49 (Jul 2, 2008)

How big is the tank?


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## willieturnip (Aug 30, 2009)

Ah that's alright then!


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## Kellsindell (Sep 15, 2008)

Didn't see it as address so i'll say it just in case... Make sure you have it near the surface or have it going to an over flow box then being drained that way. IF you don't then you run the risk of draining too much water and causing the sump to overflow if the power turns off, and that's a great big mess.


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## jzon414 (Nov 1, 2009)

105 gal

so when u say thats alright then do u mean that you agree with me that its prolly not tempered?

and kellsindell - yeah i already knew that one, but thanks anyway for lookin out


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## willieturnip (Aug 30, 2009)

When I say that, I mean "that's alright, the tanks sound then". 

It's impossible to tell if it's tempered or not. The only way to know is to drill it and see, not that I would recommend that.


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