DIY dual overflow

[FishyFishy!]

If those are plastic/acrylic dividers in that sump, be prepared to replace them, or have to tear down the sump to re-silicone them in. I did the same thing, and 6 months down the road all the dividers had come loose. Silicone has a very poor bond to acrylic.

If you're thinking long term, might want to consider glass baffles.

Ever considered just drilling the tank and making a normal overflow? That contraption, though it looks like it is working well, would scare the crap out of me lol. I wouldn't be able to sleep at night.