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Overflow Box?


SmoothSmoke

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My plan was to drill my 29 gallon acrylic tank. But after researching, I've read that an overflow box is needed. I just am not grasping the concept of an overflow box

 

Why cant I just have a bulkhead with a strainer like pictured below? If I need an overflow box, then why drill the tank?

 

UVc5VS8l.jpg

 

 

 

 

 

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an overflow box increases the area from which you take water, so most of the water comes from the surface and "skims" the surface so you don't have a greasy film on the water. I don't know how well a drain like that would accomplish that, maybe very well, maybe not well at all.

 

I've always like this simple style of drain cover, just don't know how well they truly work. I also think it would be easier to clog.

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skimlessinseattle

Overflow box helps to more efficently skim the surface of the water. The drains behind the overflow are lower than the overflow wall itself. With a strainer at the surface, unless you are using a monster pump to move a lot of water, the surface tension of the water wont break, keeping a sludge slick on the top of you water. Gravity assists in breaking this tension with an overflow.

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circusordie16

more importantly than either of those is that the overflow box limits the amount of water that can get sucked back in to your sump in case of a power failure where the return pump goes out. If the pump goes out in your current situation the water in the display will drain down to the bottom of your pipe (an inch or so). if you had an overflow box set only 1/8" or 1/4" below the water surface then only that amount of water would drain down to the sump. if your sump is big enough to hold the inch worth of display water then it doesnt really matter (although corals up top could be exposed).

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skimlessinseattle
more importantly than either of those is that the overflow box limits the amount of water that can get sucked back in to your sump in case of a power failure where the return pump goes out. If the pump goes out in your current situation the water in the display will drain down to the bottom of your pipe (an inch or so). if you had an overflow box set only 1/8" or 1/4" below the water surface then only that amount of water would drain down to the sump. if your sump is big enough to hold the inch worth of display water then it doesnt really matter (although corals up top could be exposed).
This assumes the returns aren't lower.
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That's a pretty valid question. I think the best answer is that as a surface skimmer, an overflow box is more efficient at transmitting a larger flow rate to a pipe of a given diameter than an open orifice of the same diameter as the said pipe.

 

Without the overflow (box of water) in front of it intake velocity is greatly increased, and the bulkhead fitting/strainer would suck air into the pipe which would greatly diminish flow.

 

All that aside, if you aren't running some monster return pump, a bulkhead fitting with a strainer will work just fine.

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An open bulkhead like the one shown will either operate at full siphon which would require a finely tuned return(nearly impossible) or it will suck air and make a lot of noise

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Jackal_Knight

You could, my self and a few other ppl run a just a bulk with screen, works fine and is silent the only down side is when the pump is off the water lvl drop quite a bit.

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If I need an overflow box, then why drill the tank?

 

You don't need to drill to have an overflow box. There are two types of overflow boxes.

 

Ones you have to drill, like this.

1320190053482640143378.jpeg

 

And ones that use a siphon.

lg_pre.gif

 

You can do what you have pictured like Jackal does, and if you ever want a surface skimmer in the future you can buy one and silicone it around the existing drain hole, but the hole would have to be lower than what is pictured to work properly.

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You don't need to drill to have an overflow box. There are two types of overflow boxes.

 

Ones you have to drill, like this.

1320190053482640143378.jpeg

 

And ones that use a siphon.

lg_pre.gif

 

You can do what you have pictured like Jackal does, and if you ever want a surface skimmer in the future you can buy one and silicone it around the existing drain hole, but the hole would have to be lower than what is pictured to work properly.

under no circumstances should you use silicone inside an established tank, you'll nuke everything.

 

you can add a closed overflow box like the first pic (glass holes kit) after the fact becuase it doesn't need silicone, it's completely sealed and sealed to the bulkhead.

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Thanks all! Now I'm getting the picture of the benefit of having an overflow box. I will be drilling my tank. Planning on a 1" bulkhead which will drain approximate 300gph. Return pump will be a 500gph pump to account for the 3-4ft height getting the water from the sump to the tank.

 

This one on Ebay is rated to 500gph. Is this the one that will fit my needs? Anything else missing if I purchase this box?

 

http://www.ebay.com/itm/500GPH-NANO-Overflow-Box-CORAL-REEF-FRAG-AQUARIUM-/161149888781?pt=Fish_Filters&hash=item258548290d



My tank is empty, so it's OK to use silicone to attach the box now? Also, the tank is acrylic if that makes a difference?

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Thanks all! Now I'm getting the picture of the benefit of having an overflow box. I will be drilling my tank. Planning on a 1" bulkhead which will drain approximate 300gph. Return pump will be a 500gph pump to account for the 3-4ft height getting the water from the sump to the tank.

 

This one on Ebay is rated to 500gph. Is this the one that will fit my needs? Anything else missing if I purchase this box?

 

http://www.ebay.com/itm/500GPH-NANO-Overflow-Box-CORAL-REEF-FRAG-AQUARIUM-/161149888781?pt=Fish_Filters&hash=item258548290d

 

My tank is empty, so it's OK to use silicone to attach the box now? Also, the tank is acrylic if that makes a difference?

what overflow box are you wanting?

 

personally I'd go with something similar to the glass holes box, then you don't have a bunch of messy silicone in your tank. I'm really happy with mine and it has a low profile. also allows you to take it off if you need to.

 

if you are attaching it to acrylic, the proper way would be with an acrylic bonding agent..

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what overflow box are you wanting?

 

personally I'd go with something similar to the glass holes box, then you don't have a bunch of messy silicone in your tank. I'm really happy with mine and it has a low profile. also allows you to take it off if you need to.

 

if you are attaching it to acrylic, the proper way would be with an acrylic bonding agent..

 

You're absoultely right. The glass holes kit looks better, and no silicon needed.

 

Would this work for my tank? It says rated to 300gph, but below it says 200gph.

 

http://www.glass-holes.com/Super-Nano-con-Dientes-Overflow-Box-Complete-Kit-ghsndienteskit.htm

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You're absoultely right. The glass holes kit looks better, and no silicon needed.

 

Would this work for my tank? It says rated to 300gph, but below it says 200gph.

 

http://www.glass-holes.com/Super-Nano-con-Dientes-Overflow-Box-Complete-Kit-ghsndienteskit.htm'>http://www.glass-holes.com/Super-Nano-con-Dientes-Overflow-Box-Complete-Kit-ghsndienteskit.htm

 

The 200gph is the recommended max, it can run more but that is what they recommend. Keeps a nice buffer there so people don't flood..

 

It's based on how much flow you want. If you're looking to push 400 or 500gph (anything overt about 250 really) through it I'd recommend the 700gph box. Even the 700 is pretty small, but obviously more expensive.

 

What pump did you say you wanted to use?

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The 200gph is the recommended max, it can run more but that is what they recommend. Keeps a nice buffer there so people don't flood.. It's based on how much flow you want. If you're looking to push 400 or 500gph (anything overt about 250 really) through it I'd recommend the 700gph box. Even the 700 is pretty small, but obviously more expensive. What pump did you say you wanted to use?

 

Not sure on the pump. I wanted to purchase the overflow box. Then I'd match it up with a pump. I'm probably wrong on the way I'm going about it. Maybe I should just buy a pump first, then match the box to it.

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Doesn't matter either way really. What size sump are you using?

 

Also, reef central has an excellent head pressure calculator on their home page.. Not that I'm trying to push anyone to reef central..

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My sump is only 10 gallons. It will be only 2 chambers. Here is my design thus far. I'll probably be making it this weekend.

 

sump.jpg

 

I just did a quick search on pumps. The Lifeguard Aquatics 2200 has caught my eye. Not too expensive and it's rated up to 594gph. Their 3000 model is rated up to 819gph and just a few bucks more. If I can control the return flow with a ball valve, I may end up going with the 3000.

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You're not going to want anywhere near that much flow through a 10g sump IMO.. The 594 pump is the biggest pump I would use and that's really pushing it. I have a 500gph mag 5 running my 20g sump (but it's also a fuge).

 

And if you're going with either of those pumps you'll need at least the 700gph kit. Probably an even larger one for the 819gph pump.

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You're not going to want anywhere near that much flow through a 10g sump IMO.. The 594 pump is the biggest pump I would use and that's really pushing it. I have a 500gph mag 5 running my 20g sump (but it's also a fuge).

 

And if you're going with either of those pumps you'll need at least the 700gph kit. Probably an even larger one for the 819gph pump.

 

Their smaller model is only rated at 296gph. I'm thinking the 594gph with a ball valve to control the return flow? I just used the calculation on the other site and came up with 520-560gph. Thanks a lot! I really appreciate the help. You're making everything make more sense. In essence the return pump regulates the drain pressure as well?

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Well, you want your drain rated for more than what you can pump with the ball valve wide open. Another thing you'll want to do is make sure your drain line is larger diameter than the return pump line.

 

It's really simple one you've done it.. It's all a bit confusing until you've plumbed one and understand it all.. Twice as confusing if you're using a hob overflow..

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So the overflow kit from glass-holes rated at 700gph, combined with the return pump rated at 594gph should do the trick?

 

Just heard back from Glass-Holes. Sounds like either or will work, but the 700 is the better choice. Here is what he wrote.

 

 

29’s can usually get by with a super nano con dientes, but a 700 is a better choice if you have space for the plumbing. For an acrylic tank, use the ‘delete hole saw’ option, and get a hole saw at your local hardware store. For a return pump, something in the 250-300gph range, a little less if you go with the super nano con dientes, 250 max at your head loss.

 

Just don't get what the head loss is about.

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Head loss is the amount of pressure lost by pumping vertically from your sump. The pumps are rated for "x"pressure at the pump outlet, so

"x"- headloss = the flow rate at the return in your display.

 

A 500gph pump after 3 feet of head may only pump 380gph at the display tank.. Make sense?

 

Sounds like your have it pretty well figured out. Do some googling on how to drill acrylic, you don't wanna screw that up.. I'm no help there, I've never used a hole saw on acrylic.

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Thanks a lot! Went with your suggestion and purchased the 700 box at Glass-Holes.

 

Now it's time to decide on a return pump. Looking at these two in particular. They're practically the same price.

 

Livegard Aquatics 1200 - 296gph

http://shop.marinedepot.com/lifegard-aquatics-quiet-one-pro-series-aquarium-pump-1200

 

Hydor Seltz L30 - 320gph

http://shop.marinedepot.com/hydor-seltz-l30-pump-320-gph

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My sump is only 10 gallons. It will be only 2 chambers. Here is my design thus far. I'll probably be making it this weekend. sump.jpg I just did a quick search on pumps. The Lifeguard Aquatics 2200 has caught my eye. Not too expensive and it's rated up to 594gph. Their 3000 model is rated up to 819gph and just a few bucks more. If I can control the return flow with a ball valve, I may end up going with the 3000.
Only thing I suggest is making your skimmer area 12 inches and your return 6.5. You always want your skimmer area big as possible. Also 250-300 gallons is more than enough for a 29 gallon tank. I run 300 gph thru my 60 gallon tank.

 

Thanks a lot! Went with your suggestion and purchased the 700 box at Glass-Holes. Now it's time to decide on a return pump. Looking at these two in particular. They're practically the same price. Livegard Aquatics 1200 - 296gphhttp://shop.marinedepot.com/lifegard-aquatics-quiet-one-pro-series-aquarium-pump-1200'>http://shop.marinedepot.com/lifegard-aquatics-quiet-one-pro-series-aquarium-pump-1200 Hydor Seltz L30 - 320gphhttp://shop.marinedepot.com/hydor-seltz-l30-pump-320-gph'>http://shop.marinedepot.com/hydor-seltz-l30-pump-320-gph
Bad ass return pump here you won't be sorry. http://www.ebay.com/itm/Sicce-Syncra-1-5-Silent-10-mt-357-GPH-/200959966882?pt=LH_DefaultDomain_0&hash=item2eca25bea2

 

Also you can burn up some pumps by restricting the flow with a ball valve. The back pressure the valve creates shortens the life of a pump.

 

Drilling acrylic is super easy! Just like drilling wood if you ask me.

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Thanks Lawnman. So as to no damage the pump. I should look for something in the 200-250gph range? I see the Sicce has a 1.0 version that is rated at 251gph max. Should be suffice for my 29gallon DT, 10 gallon sump?

 

Also I made the return zone bigger on the design so I wont have to worry about flooding the sump? If the skimmer area is bigger, it really doesn't make a difference to prevent flooding if a power failure were to happen?

 

In other words, it doesn't matter which zone is bigger when trying to prevent a flood as the whole sump itself will be the safety measure? Not just 1 zone in specific.

 

Hope that makes sense, I can ramble sometimes.

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