Need help to pick overflow box

[lpsouth1978]

Yes, both boxes are very similar. I think the fiji cube is a quality box also. Only real difference is the cubes external box sits lower than the internal. I have since learned the height of your primary should determine the lowest water level your tank will drain to. At least that’s what MM told me in a recent email. I had figured water loss to the bottom of the bulkhead fittings. I guess this was incorrect. Here’s a picture to the lowest water level. Not my pic, but an example. Of course you’d have to use a siphon break on the primary to stop it at this point. Which then upon start up it wouldn’t become a full siphon until the hole was submerged. Fluid dynamics mess with my head. Lol!!! I sent them a pic of this and asked if this would be the lowest water level. They replied yes. So that would also be the lowest water level in the aquarium also. I’m thinking they both should equalize.

If they told you that would be the lowest water level in your tank, STAY AWAY!!! If my tank drained to that level I would have a serious mess on my hands. Is that because of the way the internal box attaches to the external? My tank only drains to the bottom of the weir, which is well above the level you marked. I have the EMS overflow, but my old Eshopps Eclopse was the same way, just drained to the bottom of the weir.

 

[JCTReefer]

If they told you that would be the lowest water level in your tank, STAY AWAY!!! If my tank drained to that level I would have a serious mess on my hands. Is that because of the way the internal box attaches to the external? My tank only drains to the bottom of the weir, which is well above the level you marked. I have the EMS overflow, but my old Eshopps Eclopse was the same way, just drained to the bottom of the weir.

That was just an example. I would actually plumb the primary higher than the picture. Modular marine is not a sealed design. It’s different the Eshopps and EMS overflow. The internal weir is removable. The size sump I’m going with should accommodate a worst case scenario if that is the lowest point it would drain to. I’ll just have to do some experimenting in the garage to make sure there’s no overflowing of the sump issue. Water seepage would be minimal I think around the inserts. I could always just glue it into the bulkhead and be done with it, but that would kind of defeat the purpose of a serviceable/removable weir. It’s too late now, I’ve already received the custom box. And on top of that, I had the bulkhead holes made to whee they would meet custom Aquariums hole spacing requirements. So that even further down from the top than a stock overflow. So that would mean even more water. But, I’m thinking if I plumb it right, I should be able to make up for that water loss. Time will tell!!! It’s giving me a headache just thinking about it.