Personally I say get them to grind out the glass and smooth it to the 1.5". Then come ip with a plan. I recommend using 1.5" anyways. As you flow water over the weir, the actual water height will be above the edge of the weir. By how much depends on the flow. At moderate flow rate you might only have .25" between the top of the glass and the water if you stick with .75". What were the dimensions you were shooting for in the weir? What flow rate will you have? I'll do the math for you and tell you what the water height will be.

my thoughts.. how did you order this? did you supply the glass and have them notch it or are you buying a finnished product? if you supplied the glass and it cracked then yes you have to make due but if you phone up and go a quote on a chunk of glass cut to your spec, then they need to fufill the order and there mistake is on them, not you.

in my opinion 1.5" is hugeand unless you realy crank up the flow you are only going to have 1/4" of water above that. to me gluing a chunk of plastic or glass on the inside is just going to be ugly, but that is my opinion.. see what it would cost for a new pane of glass with the notch, then decide which way.. mind you if it is a big chunk could be expensive so that might make up your mind right there. but it would also give you the opertunity to go to a bigger glass thickness which would reduce the chance of breakage due to the cutout.

Steve

ya and there is no silicone on an ecrylic tank. won't work.

Steve

Yeah he's outta luck Steve I had asked him that already:

Still sucks tho. Rounded corners would certainly be better too. It seems pretty common for shops to use circular bits for the corners and then to cut the horizontal out. Sharp turns are a weak point too but at least this is not a high-pressure area... silicone and acrylic will be strong enough.

When we cut glass, it doesn't always work out as planned. There are some cuts that are so complicated that we have to take them to a professional glass cutter. The best example of this is our one piece euro bracing. Part of the cost of these cuts is the risk that the glass will break. If it does break, the glass cutter will redo the cut, but we have to supply the replacement glass. There is also considerable over cuts on a one piece euro needed by the machines while working on the center cuts.

The point is, glass breaks. We assume the risk when building a tank, but would never do so on a prebuilt tank. Part of calculating the cost of a custom tank is the risk of breakage. We have lost money on tank builds due to inaccurate cuts, scratches and breaks.

Nonetheless, I think a 1.5 inch overflow will work fine. If you put a wave box in the tank, it's pretty close to ideal.

- Brad

ok what you could do if it is too deep is ask them to make a new pannel to the original spec. then just replace the pannel of glass. I had to do this on a tank I broke when moving.

Steve

we didn't know it was a prebuilt at the time hence the question on weather it is or isn't. and we all know that if you take a tank in and ask for a hole in it you do so at your own risk.. the whole issue was if he took a tank in and asked for it to be modified or if he ordered a tank this way..

it turns out it was a tank he just took in for modification.. so ya he is out and either replace the pannel or make due...

if he ordered it that way then it is the tank builders dime not his.

Steve

Thanks for the input guys, I'll probably just get him to try and smooth it out so I'm sure the water level will flow over the entire length. I think I can live with 1.5". I'll let you know how it goes.