I don't know why anyone is having issues with this overflow unless they didn't read the description. I have it installed on my 40 ga breeder reef tank and it took maybe 15 min to get it up and going, but only because I washed it prior to putting it on due to the strong new acrylic smell. I will say the tube to suck the air out is a little bit too short if you can't get beside your aquarium, however, if you own an aquarium I'm sure you have plenty lying about so it wasn't a big deal. If you run into the issue of not being able to get all the air out of the u-tube, once you start up the pump and flow is going just wiggle the tube until the moving water pushes it out (shouldn't take more than 5 minutes depending on your return pump strength. If it seems to not be keeping up with your pump then you need to add a piece of tubing under the u-tube like I did because it means the bottom of the tube is too close to the bottom of the skimmer box (I included a picture of what I mean) I have a rio+ 2500 pump with a 4ft rise and am very sure I could use an even stronger pump with no issues.

Great product and never lost siphon after ~6 months. However, it is LOUD and the sounds is inconsistent depending on how the water flows down. But it does the job.

Product itself is great but eshops instructions with this an just about everything they make could be written better by my pug dog or anything else without opposable thumbs. The products for aquariums are already overpriced, would it be that awful to include pictures with your instructions? Especially if you are going to be clear as mud with your details.

Pricey but good. The only complaint is it's very loud. Even with the "noise reducer" which is a clear tube made into the pcv pipe. Ditch that and do a DIY silencer, look it up on youtube. Costs less than $5 to make from pvc pipe. The only other minor issue is the plastic wing nut screws on the overflow, turn them the opposite way than what the directions say. You cannot adjust it once it's on the tank if you install how they tell you to because you can't get to the wing nuts because they'll be between the box and your tank. Stupid design in my opinion on that part. But no further issues after.

I'm kind of shocked here and maybe I'm missing something but I trust Eshopps as I've bought plenty of their products in the past. This is a fairly good overflow but don't expect to out 800gph thru it as it comes out of the package or probably at all. I had a Danner Mag Drive 5 running 500pgh and this overflow struggled to keep up not to mention how long it was. I eventually dropped the flow down to about 300gph and put in a stockman standpipe and its now running fine and quiet. Just don't expect to get out of this what it's advertised. I bought it thinking I would only be using about half it's capacity, truth being it can only handle a bit over half of what it's advertising.