After a diy design for overflow box, or site

[dearis]

Hi there,
I am planning my 4x2x2, I am getting it drilled for standpipe and returns. I am after a DIY design for the overflow box with parts fairly easily found. Alternatively a sound Australian site the sells them at reasonable cost.
I have done my searching but to be honest I don't know if it is called an overflow box or weir or something else
any help would be great
Regards Darren

[OneDummHikk]

An internal overflow box? It can be as simple as a thin sheet of acrylic from a building supply store (not sure how easy it will be to find down under though). The acrylic doesn't have to be very thick because there is equal water pressure on both sides of the plastic.

It needs to be as tall as your tank is deep. Then, cut it to width to wrap around your overflow drains. Simply take a heatgun, torch, or an oven and heat the acrylic up enough to bend it. Then bend the corners into it (that prevents having to glue it together). When you get it the right shape, let it cool.

Then, it is simply siliconed into the tank using reef safe silicone.

[crvz]

Do you have room to make an external end-to-end overflow (coast-to-coast)? May not be feasible if the tank is already built, but it would be a great solution. Otherwise, if the tank is being drilled, the overflow is just a couple piece of acrylic or glass to make a box over the holes.

[OneDummHikk]

Internal coast to coast overflow