Modular Marine overflow sizing question

[BAPrince]

JUST (last week) placed my order with Planet Aquariums for a 220g (66x30x24). I'm going to have them drill it for a Modular Marine overflow, which I need to order soon so they can ship it to Planet. I am going with a minimum of their 2400 model, because it comes with 1 1/2" drains. Question.... is there ANY disadvantage to going bigger with the skimmer box, other than visual... and can it be TOO big? The only difference I can see between the 2400, 3000, and 3600 is the length of the skimmer box (24", 30", and 36"), and they are all rated "up to 300g".... so, how do you choose? Thanks in advance!

 

[Gablami]

By skimmer box you mean the internal box inside the tank, right?

No, in my opinion, besides the visual aspect, no downside to having a longer box. You might already know this, but the weir extends along the front and the back of the box. Pretty cool.

 

[BAPrince]

I did NOT know the weir was also on the backside... that IS cool!

So... follow up question then... is there any ADVANTAGE to having, let's say, a 36" weir on a 220g tank? With the tank being 66" long, I can fit any size. And, I don't want it be huge with no benefit. Can the weir be TOO big and cause other problems?

 

[Gablami]

You’ll get more surface skimming the longer the internal box is. It can drop the water level very slightly if you’re running the same amount of return flow.

 

[DaneGer21]

I have a 60x36x24 tank and I went with a Modular Marine 36” internal box, but I had them make it with the “smaller” external box and 1” drains. They flow plenty for me. I love it.

 

[billwill]

Better make darn sure that Modular Marine can provide you an overflow in the first place. When I got my 150G a month ago, Modular Marine had no plans for making anything for anyone. I went with Synergy Reef instead. As far as wider weir, it's all about velocity. Same GPM, a wider weir will be lower velocity. I'd recommend sizing to the real flow rate you're planning.