I am in the process of making a 30 Gal - Long Freshwater Refugium/Sump. I currently have a 3D background in my 29 Gallon Lake Mal Cichlid tank so i do not have much room for a "internal" overflow box to carry the water into the external box, where the siphon could be kept during a power outage. I have seen the system that some people have used with the pvc running to the bottom of the tank then going back up and out, tie-ing into a T then running to sump below, but am leery of this idea due to a lot of comments regarding this system loosing suction. My tanks are at my office so i do not want to have a siphon break to cause a massive flood. any ideas on how to make the Internal/External Overflow box work with very minimal space on the inside of the tank?

do i need to have an internal box or can i just have my siphon run from the tank to the external box and have my overflow pipe be above where the two ends of the siphon are?

Yeah, I've seen both of his; as well as, many other videos. The only thing i am leery of, is the likely hood of the siphon to break and not restore flow after a power outage. i was thinking of doing a "hang on back" overflow box, and then having my overflow pipe in that, be just below the surface line i am trying to achieve in the main tank. that would allow for the "u-pipe" to stay in constant siphon, even during a power outage. my main thought with that though is, do i have to have an internal overflow box? i don't have much room at all (maybe 1" of space between the background and back of tank) so wouldn't i be able to just put a strainer on the end of my "u-pipe" which will flow to the external box, and water level will be determined by my overflow pipe in the external box? i just have not seen anyone who did not use the internal box when doing this type of set up?

your right about that. i am definitely over thinking it. if it ever messes up on me, i'll just change the design. i just finished the baffles on my sump/refugium yesterday, i'll post a few pictures once i get it up and running. thanks for the straight forward obvious answer. its what i needed to hear! have a good one.

topic5096.html sorry lol