Drilling for Overflow and Size Recommendations

Ryan98720 · Mar 2, 2021

I recently purchased a 36-gallon Bowfront tank with the intent of establishing a reef. It has been a dream of mine for years now! After watching some videos I think that I will be able to drill it! Just have to call and confirm that the back is not tempered first.

My question is... what size overflow do I need? I am thinking about running a Jebao 3500 return pump. From the sump to the top of the tank is about 4 feet. Marine Depot has a kit that I was thinking about using; however, I cannot find a GPH listing... Should I go with the small or the medium size?

Aquarium Overflows

Bulk Reef Supply - Saltwater Aquarium Supplies for Reef Tanks

www.marinedepot.com

DCR · Mar 2, 2021

Those overflows are basically a clone of the Eshopps overflows. The 6" small box Eshopps rates for 600 gph. I don't think I would be comfortable running it at that rate, but it should be good for 250-300 gph which is adequate for your application. Note the reviews about the leaks due to an inadequate number of supplied gaskets. You will have to deal with that. A lot of people do not like the noise and tuning problems created by the low elevation of the external box. There is a recent thread on this. It is a budget friendly option if you are willing to accept those issues.

Ryan98720 · Mar 2, 2021

I have definitely seen the reviews about the leaking gasket... I figured I could just fix it by just getting an extra gasket from Home Depot or something... As far as gurgling and noise complaints I have not heard that.... If I were to put a ball valve on the main overflow and dial it in to match my return pump could I prevent the noise? I know you don't want to put a valve on the emergency drain, but wouldn't a ball valve on the main drain help? I'm thinking I may just spend the extra $10 on the Medium size just as a precaution. I'd rather just dial back the flow than not have enough. Is that a bad way to think? Also, I figure if I ever upgrade to a larger tank, I could take the medium off and use it.... Is this a poor way of thinking about it?

DCR · Mar 2, 2021

My impression is that the noise comes from the water fall inside the internal overflow box. The water level in the external box is largely fixed by the elevation of the box which is about 2" below the internal box. Consequently, there is a 2" water fall inside the internal overflow box. With low flows, it may not matter that much, but that may be a reason to go with a medium size box. The better overflows like Modular Marine and Exotic Marine have the the internal and external boxes at about the same level

Ryan98720 · Mar 3, 2021

Oh okay! Well! I looked at the Modular Marine and Exotic Marine and they both appear to be out of my budget! Hopefully the Marine Depot will work well enough! I though maybe I could put some filter floss or something in that compartment to keep the sound down if I had too! But I hope it isnt too bad! You have definitely convinced me to go ahead and get the medium size overflow.