Overflow box - I need help!

lilreefgirl

lilreefgirl

Reefing newb
I am trying to figure out what I need to do to build an internal overflow box/plumbing.

I have a Mag 9.5 pump, the display tank is 47.2 x 15.7 x 19.7 (rimless) approximately 1/2 inch thick, the stand is not built yet, but it will sit approximately 36" high with a 29gallon sump underneath.
I would like the overflow box to sit in the back corner and the PVC inside be hidden by the overflow box (wonder if I can buy black or blue glass and have it cut with the combs at the top??)

I am having someone drill my tank (2 holes - in the bottom, intake and return). I dont know how big the holes need to be drilled & what kind of pvc/plumbing I need with the equipment I have.

Can anyone lend me some advice - is there a standard that should be followed, or do you have to be a plumber to understand what needs to be done? It would be great if someone has a design that I could look at or knows where I could find one!

Everything is coming together, and I dont want to get this wrong and have either a loud overflow or one that does not work as it should!

Thanks everyone!! :bowdown:
 
you can find a lot of info here and there are some good links on the page as well

Melevsreef.com | Acrylic Sumps & Refugiums

as long as it drains faster than the pump can return it there wont be a problem. you can get black acrylic and have it cut pretty easily.

it is easy to do. just draw out what you want and really think it through. you can get bulk head fittings offline in all sizes. for a mag 9 ( depending on head loss) i would say 2 x 1.5 inch drain hole would probably be enough. i have a one on my overflow and it keeps up just fine and i have a mag 7
 
Are you saying 2 drain holes in the DT? each 1.5" in diameter?
Then I need a return hole drilled as well (I dont want anything coming up the back of the tank if I can avoid it)
I was planning on having the return come over the top of the internal overflow box.

If I need to have 3 holes in the bottom of the tank, that is going to take up a lot of room - I may have to rethink the placement if that's the case....:frustrat:

Isnt this fun!? :bounce:
 
You only need two holes -- one drain and one return. Lots of tanks have two drains, but it's not necessary.
 
Bifferwine said:
You only need two holes -- one drain and one return. Lots of tanks have two drains, but it's not necessary.
Click to expand...

*WHEW* that's what I thought...I hadnt seen any others with 2 drains.

I was just thinking, does the PVC have to be 1.5" in diameter, which would make the hole bigger in order to accept the bulkhead?
I really just dont understand the flow rates I guess. :(
 
one large one should do it. i only have one on mine. but i always worry that if it got clogged i would have a mess. and knowing my luck it would happen the one week i would leave for something
 
Is it better to drill the bottom of the tank, or drill the back??
I was told today that I couldnt make my own internal overflow box because the silicone I would need to use would not bond to the silicone already used to put the tank together. He said I "needed" to drill the back of the tank and build the overflow out of acrylic and put it at the top of the tank.
thoughts, comments?
 
Huh? That doesn't make sense to me. If it's getting siliconed to the glass what difference does it make that there's already silicone there? All you do is silicone two piece of acrylic in to make a box, seems simple enough to me.
 
This is a picture of the back of my tank.

IMG_1115a.webp

I probably would've prefered out the back vs. the side but you get what you get second hand. As for drilling the bottom you have to make sure it's not tempered glass.
 
coolhandgoose said:
This is a picture of the back of my tank.

View attachment 6405

I probably would've prefered out the back vs. the side but you get what you get second hand. As for drilling the bottom you have to make sure it's not tempered glass.
Click to expand...

Definitely not tempered glass - I called the company!

He was talking about drilling at the top back of the tank - making an overflow that was not attached to the tank, but to the overflow pvc pipe...basically a "floating box" at the top of the tank....I think it would look stupid.

He was saying that because the tank is siliconed together, there is silicone in all the joints. He said that new silicone would not bond with cured silicone. (personally I think he was full of it) I've seen it a million times , even in the pic you just posted! It is done all the time when people make DIY sumps, right?

Check out the previous post, the PVC-in-PVC idea. My dad and I were talking about this today. I think it would look better than a box in the corner, and I could hide the PVC by aquascaping around it?
 
That would probably look pretty cool. I'm sure someone can chime in about the spacing and size of the holes since you don't want the holes too close together otherwise you can compromise the integrity of the glass.
 
coolhandgoose said:
That would probably look pretty cool. I'm sure someone can chime in about the spacing and size of the holes since you don't want the holes too close together otherwise you can compromise the integrity of the glass.
Click to expand...

That is what I was concerned about...
oh, and how big does PVC come? If it was a 4-5" diameter pipe, it might work?? I guess I would need to know what the standard spacing between pipes normally are, then figure it out from there...
 
Last edited:
that size pipe is going to be huge. i have a 2 inch on mine and it drains really easily. but you can get pvc all the way up to like 10inch. you might have to special order it though
 
Rcchanlder said:
that size pipe is going to be huge. i have a 2 inch on mine and it drains really easily. but you can get pvc all the way up to like 10inch. you might have to special order it though
Click to expand...

Oh, no.... You don't understand, the 4-5" pvc is not drilled. It only sits over the 2 drilled pipes. The big pvc is acting as the overflow box and is only siliconed to the bottom of the tank like any other square overflow box. :D
 
Can anyone lend some advice about this project?

How far apart do the holes in an overflow have to be?
What size do the holes have to be (ie: flow rates using a Mag 9.5 return with a 36-48" rise)?? The stand is not built yet, but will be approximately 36" tall. The sump is about 18-19" high, so the base of the display should only be about 1-1.5 feet above the top of the sump itself) - if any of that information helps?!?!

Can I drill this myself, or would I need to be skilled at glass drilling??
How do I figure out the size the holes need to be to pump the right amount of water back into the DT??

I purchased this tank for an amazing price, to replace it could be over $200 (I paid $62!!) It is a Hagen Waterhome, rimless, the glass is about 1/2" thick!
I called Hagen, and NONE of their tanks have tempered glass.

I am stuck...please help! :shock:
 
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