Modular Marine External Overflow or Permanent Built in External Overflow?

[~MD~Reefs~]

Hey Guys! I am getting a custom acrylic tank done. Would you guys go with Modular Marine External Overflow or Permanent Built in External Overflow? I didn’t even know a built in external overflow was an option until recently, anyone know the pros/cons to it? Also, would I be ok with 2 drain holes or should I really go for 3? Tank will be between 75 gallons-100 gallons.

Appreciate any input

 

[exnisstech]

I like the cleaner look of the permanent overflow and no bulk heads to deal with and no lost real-estate in the DT.
I'll let someone else comment on the number of drains.

 

[Rothric]

3 drains, no question. You'll be able to set up a Bean Animal style overflow and tune it so it's extremely quiet.

 

[cilyjr]

3 drains, no question. You'll be able to set up a Bean Animal style overflow and tune it so it's extremely quiet.

2 holes can also allow for a quiet syphon style drain system as well.

The 2nd trickle drain is modified so the air intake is just above the water height so if the water rises above the air intake the second will siphon the water down. If it happens it will make sounds similar to a toilet flush and alert you to an issue that needs correcting.

 

[Fish Fan]

I prefer external and 3 holes, but I will say if you go with a typical overflow, I think the Modular Marine is the way to go.

Good luck!

 

[X-37B]

I have 2 IM ext systems and one RS internal.
Permanent overflows would be my choice over the MM.

 

[Rothric]

2 holes can also allow for a quiet syphon style drain system as well.

The 2nd trickle drain is modified so the air intake is just above the water height so if the water rises above the air intake the second will siphon the water down. If it happens it will make sounds similar to a toilet flush and alert you to an issue that needs correcting.

More difficult to keep a 2 drain system quiet in my experience. 2 drain systems require frequent adjustment of the gate valve as things change (pump efficiency, algae buildup, etc). The 3 drain style is much more a set it and forget it.

OP, If you have the option right now as you design the tank, I'd highly suggest getting 3. You'll be happier in the long run.

 

[~MD~Reefs~]

More difficult to keep a 2 drain system quiet in my experience. 2 drain systems require frequent adjustment of the gate valve as things change (pump efficiency, algae buildup, etc). The 3 drain style is much more a set it and forget it.

OP, If you have the option right now as you design the tank, I'd highly suggest getting 3. You'll be happier in the long run.

Long story short, I inquired about a 48x24x16 custom acrylic tank. Builder told me he actually has the materials for a 48”x24”x18” on hand, probably someone backed out? He gave me an insane deal, $700 shipped. Polished rounded edges, black back, black bottom. Crazy deal. Butttt…. it seems like he already has the external overflow drilled for only two 1” holes. I will ask him tomorrow morning if it’s not too late to add a third hole. Looking back at the pictures now, it seems like there’d be space to drill another hole in the center? Should be easy enough. Or I’d even be willing to pay for labor+materials to cut a new piece if they haven’t already started welding. I was ok settling for two drains given the good deal but can’t hurt to ask if it’s possible to make a third hole.

 

[Fish Fan]

I would prefer to have three drain holes, but a deal is a deal. See if they or you can get another hole in there.

 

[cilyjr]

More difficult to keep a 2 drain system quiet in my experience. 2 drain systems require frequent adjustment of the gate valve as things change (pump efficiency, algae buildup, etc). The 3 drain style is much more a set it and forget it.

Why? When the third drain is supposed to be completely unused except for an emergency?

 

[~MD~Reefs~]

Why? When the third drain is supposed to be completely unused except for an emergency?

Thats what im confused about too. I keep hearing that comment. But in my current bean animal setup, the third drain is completely dry, not water has ever gone through it. Ive only ever played around with primary/secondary drain to fix noise

 

[exnisstech]

I would prefer to have three drain holes, but a deal is a deal. See if they or you can get another hole in there.

Why? When the third drain is supposed to be completely unused except for an emergency?

Thats what im confused about too. I keep hearing that comment. But in my current bean animal setup, the third drain is completely dry, not water has ever gone through it. Ive only ever played around with primary/secondary drain to fix noise

I have two tanks running with two drain pipes. I also have a tank running with three drain pipes. Given a choice I would choose three but I wouldn't hesitate to buy a two drain system for the right price. While it's possible to get both quiet the two drain systems require occasional tweaking of the gate valve where the three hole system is more set it and forget it. I can't explain why this is but it has been my first hand experience.

 

[~MD~Reefs~]

I have two tanks running with two drain pipes. I also have a tank running with three drain pipes. Given a choice I would choose three but I wouldn't hesitate to buy a two drain system for the right price. While it's possible to get both quiet the two drain systems require occasional tweaking of the gate valve where the three hole system is more set it and forget it. I can't explain why this is but it has been my first hand experience.

I talked to builder and he’s going to add another hole and add an overflow lid for $65 which I can’t really complain about since I already got a crazy deal on the tank

 

[X-37B]

I Ran the 2 hole system for 30 years and it worked well. Never had an issue. My 3 current systems are 3 hole.

I will run 3 hole now on any future system. The 3 hole is there to protect your main if a snail crawls into it.
I always cleaned the main drain on my 2 hole systems once a year.
I always pull out snails but no trochus or larger types found.

Good that you got a cover on the overflow. I have never had a large snail get in with a cover.

I have picked up snails that climb out of the system and end up on the floor.

Get a lid for your new system, along with the overflow cover you will be good to go.