Installing a weir into your marine tank
The weir is another element of your tank which at first seems quite difficult to understand how and where the weir should be installed and also where to get all the materials together and install yourself. But once you have a small amount of information at your disposal you can quite easily design and create your tank weir.
Location of the tank weir
You can basically install your weir anywhere, so if you are drilling a hole and placing a weir around it as long as the weir creates a separation area from the main body of water and the hole is below the top of the weir I would say anything goes. It could be in the centre, the right corner, left corner, somewhere in-between or a combination of these options. The drilled hole can either be drilled in the bottom of the tank or in the back of the tank. I would say the ideal place is in the bottom but the fear that the bottom maybe made of tempered glass often means people opt from drilling in the back. To be honest there is no really disadvantage to this other than it may be easier to hide the pipe work if drilled in the bottom.
There are so many setup combinations depending on the size and shape of your tank but most will achieve similar results. Basically think about the setup you want and decide where you would prefer the weir to be. Taking into account the size and how many drain holes / return holes you want. You might not even want a hole for the return water as you could be simply bringing it back over the top of the tank.
Material it's made of
Basically you can make your weir out of glass or plastic. If you go for glass and you are able to cut it yourself or know someone who can do it then I don’t think you will go too far wrong with this method. As for plastic that’s another matter, you may have seen plastic referred to as Acrylic, Perspex, polycarbonate or even Lexan.
So what is the difference and which should you use. Well for starters Perspex is the same as Acrylic; Perspex is just a brand name for acrylic. It is the same for polycarbonate and Lexan with Lexan being a brand name for polycarbonate. According to this very useful video on YouTube (DIY Sump) the one you should use is Lexan/polycarbonate as over time Acrylic/Perspex can absorb water and warp.
The weir comb is attached to the top of the weir so that large debris does not get into the weir area but there is no restriction for the water. This can be placed on all sides of the weir or just one or two, it’s up to you and what’s best for your setup.