Internal or External Overflows

[Roc83]

Hi everyone, after doing a little research on the sump I want to build, I can't seem to decide on whether I want to add an external overflow or drill my tank and put in the internal. Usually when I cannot decide, it means I don't have enough info. So I wanted to ask y'all the pro's and con's of each method from experience? Any info would help.

 

[JoshH]

So to start off, so there is no confusion. The two different overflows you are discussing are external (typically drilled through the glass but can be notched in the glass) and HOB (Hang On Back) overflows. Internal overflows typically describe the horrendous vertical plastic overflows on many "Reef Ready" systems

Between the two either external or HOB, External is BY FAR the best overflow. And really the best overflow there is out of the 3 options. It provides you with the most flexibility for drain options (Bean animal and herbie) they can also handle MUCH more flow (up to 4 times the amount) than a HOB and usually look more appealing.

The only downside I can think of is the fact that you have to drill your tank. This can be daunting for a newbie and it might not even be possible depending on whether or not your glass is tempered. Oh and I'll add that an external overflow once you add up all the costs, usually works out to about 2-3 times the cost of a HOB if cost is an issue this is something to keep in mind.

HOB overflows are pretty easy to set up, there are a few options out there the best IMO (Not personal experience) is the Lifereef overflow. Eshopps makes almost the exact same design with some slight differences and these come in at a close second. The major downside to them is if the siphon breaks, your tank will more than likely flood over the top depending on how your sump is set up.

If you take this into consideration before hand you can design your sump in such a way that this doesn't happen. If your sump does run dry even if it doesnt flood your tank you will likely burn out the return pump unless you have something set up to shut the pump off if the water level gets too low in the return chamber. Pumps like the RO Varios come with float sensors for just this application.

 

[LiveWire]

Unless things have changed from the last time I had a HOB overflow The hang on the backs normally needs a Toms aqua lifter pump as well to start and help keep the siphon going. If you loose power there is a chance that the siphon will not start again and your sump will overfill your display.

If you can drill it I also would recommend drilling it. What size is your tank? and what are you planning on keeping in the system?

 

[JoshH]

Unless things have changed from the last time I had a HOB overflow The hang on the backs normally needs a Toms aqua lifter pump as well to start and help keep the siphon going. If you loose power there is a chance that the siphon will not start again and your sump will overfill your display.

If you can drill it I also would recommend drilling it. What size is your tank? and what are you planning on keeping in the system?

Both the Lifereef and the Eshopps overflows do not require the aqualifter to function. There design helps prevent the buildup of air in the elbow over the top.

But I second the questions you have, another important question is how much flow does the OP want running through his sump. Typically HOB overflows max out around the 5-700GPH range.

 

[Roc83]

So to start off, so there is no confusion. The two different overflows you are discussing are external (typically drilled through the glass but can be notched in the glass) and HOB (Hang On Back) overflows. Internal overflows typically describe the horrendous vertical plastic overflows on many "Reef Ready" systems [emoji14]

Between the two either external or HOB, External is BY FAR the best overflow. And really the best overflow there is out of the 3 options. It provides you with the most flexibility for drain options (Bean animal and herbie) they can also handle MUCH more flow (up to 4 times the amount) than a HOB and usually look more appealing.

The only downside I can think of is the fact that you have to drill your tank. This can be daunting for a newbie and it might not even be possible depending on whether or not your glass is tempered. Oh and I'll add that an external overflow once you add up all the costs, usually works out to about 2-3 times the cost of a HOB if cost is an issue this is something to keep in mind.

HOB overflows are pretty easy to set up, there are a few options out there the best IMO (Not personal experience) is the Lifereef overflow. Eshopps makes almost the exact same design with some slight differences and these come in at a close second. The major downside to them is if the siphon breaks, your tank will more than likely flood over the top depending on how your sump is set up.

If you take this into consideration before hand you can design your sump in such a way that this doesn't happen. If your sump does run dry even if it doesnt flood your tank you will likely burn out the return pump unless you have something set up to shut the pump off if the water level gets too low in the return chamber. Pumps like the RO Varios come with float sensors for just this application.

Good info, believe it are not my last reef in 2009 was ran off of two fx5's and hob aquaclear 110 as a refugium and I never had a issue, with my coral or fish. Thank you.

 

[Roc83]

Unless things have changed from the last time I had a HOB overflow The hang on the backs normally needs a Toms aqua lifter pump as well to start and help keep the siphon going. If you loose power there is a chance that the siphon will not start again and your sump will overfill your display.

If you can drill it I also would recommend drilling it. What size is your tank? and what are you planning on keeping in the system?

I definitely have the capability of drilling, I have my personal shop, been building paladariums, terrariums, and turtle tanks for years, just miss the beauty of a reef tank so I'm diving back in.

 

[Roc83]

Both the Lifereef and the Eshopps overflows do not require the aqualifter to function. There design helps prevent the buildup of air in the elbow over the top.

But I second the questions you have, another important question is how much flow does the OP want running through his sump. Typically HOB overflows max out around the 5-700GPH range.

My new build will be about 70 to 74 gallons tank only, depending on how I mod the used 75g I bought.

 

[jd371]

I have a HOB on my 75g running now for almost 5 years without any issues, no siphon breaks, no bubbles collecting in the U-tube over time and the siphon starts right up again after a WC or power failure. No chance of flooding if the siphon was ever to break because there's not enough volume in the return section to flood, it would run dry way before flooding. If you could drill I would, more options on the set up of a drilled tank and a much cleaner look.

 

[WVNed]

Both work equally well. I didn't want a hole in the tank so I could use it for something else later.

 

[Roc83]

Here is another question. Is better to have your protein skimmer after your refugium and run the skimmer outlet back to the initial drain area or have the skimmer next to your sock or sponge and the outlet go into the refugium? Hopefully that was not confusing.

 

[JoshH]

I have a HOB on my 75g running now for almost 5 years without any issues, no siphon breaks, no bubbles collecting in the U-tube over time and the siphon starts right up again after a WC or power failure. No chance of flooding if the siphon was ever to break because there's not enough volume in the return section to flood, it would run dry way before flooding. If you could drill I would, more options on the set up of a drilled tank and a much cleaner look.

This is exactly what I was referring to @Roc83, as long as you plan for it in advance you will not have a flood if the siphon breaks. The key thing is to know about it before you set your sump up

 

[Water Dog]

If you have a shop and drilling experience, then go ahead and drill it for a sleek, low profile ghost style overflow. As said earlier, it gives you the flexibility of using a Beananimal or Herbie style drain and gives you the ability to dial it in to make it silent. I’m partial to the Modular Marine ghost style overflows.

 

[Aardvark1134]

1) I would never use an over the back siphon style unless there is no other option. They are loud and ugly and if not done perfect they can flood.
2) I Strongly prefer internal overflows as long as the tank is at least 24 inches wide. If the tank is under 24 inches wide you can't really spare any width to the overflow and will need to go external drilled through the back not over the rim.

 

[Roc83]

If you have a shop and drilling experience, then go ahead and drill it for a sleek, low profile ghost style overflow. As said earlier, it gives you the flexibility of using a Beananimal or Herbie style drain and gives you the ability to dial it in to make it silent. I’m partial to the Modular Marine ghost style overflows.

That looks nice

 

[jd371]

If you have a shop and drilling experience, then go ahead and drill it for a sleek, low profile ghost style overflow. As said earlier, it gives you the flexibility of using a Beananimal or Herbie style drain and gives you the ability to dial it in to make it silent. I’m partial to the Modular Marine ghost style overflows.

Sexy isn't a word we use to describe things in this hobby, but that's one sexy looking overflow.

1) I would never use an over the back siphon style unless there is no other option. They are loud and ugly and if not done perfect they can flood.
2) I Strongly prefer internal overflows as long as the tank is at least 24 inches wide. If the tank is under 24 inches wide you can't really spare any width to the overflow and will need to go external drilled through the back not over the rim.

They are loud out of the box but a simple and inexpensive diy Stockman Standpipe will quiet it down drastically. I have my tank next to where I watch TV and it's super quiet. Flooding won't be a problem if set up correctly. You got me at ugly though.

 

[ca1ore]

If you have the facility to grind holes in the tank, that’s what I would do. Haven’t used an HOB overflow in probably 20 years. Maybe they’re reliable, maybe they’re not .... but to me they’re UUUUUUGLY. I also am done with mass market reef ready tanks. Better than HOB, but still mostly poorly designed and functionally limited. I would never again do anything other than an external ghost-style overflow running a triple bean-style drain. Works better .... looks better ..... no brainer IMO/E.

 

[Aardvark1134]

"external ghost-style overflow running a triple bean-style drain. Works better .... looks better"
Well unless someone can see your tank from the side then all the plumbing down the outside back looks terrible, assuming you didn't run it through the wall. Black trapezoid internals against a black back look the best by far. I will give you that HOB are ugly and so are corner internal overflows.

 

[ca1ore]

Unless, of course you design the stand with an external overflow in mind (hardly rocket science). Does sit proud of the wall if room space is problematic, but I’ll take the extra internal real estate every time.

 

[Roc83]

Unless, of course you design the stand with an external overflow in mind (hardly rocket science). Does sit proud of the wall if room space is problematic, but I’ll take the extra internal real estate every time.

Wow is that your build, if so it looks good.

 

[JumboShrimp]

Personally I'm too "chicken" to ever drill a tank myself (as opposed to have the manufacturer drill it), but there are wooden templates and drill-bit packages at CustomAquariums.com for under $25.00 if you are brave enough. Best wishes.