Please help me with my overflow box

[itzafugasi]

my new tank is a 55 gallon and will be fowlr. i have an overflow box going down to a sump and a mag 7 pumping water back up into the aquarium. please help w/ the following issues:

1. my overflow is rated at 500gph, and the mag 7 is probably between 450-480 w/ the 3 1/2 - less than 4ft head height i have. my overflow box is not filling up all the way and is creating air bubbles when the water splashes down. is this a common issue and is it a problem if the overflow box does not fill up all way? i have no restriction on the pump. i have a ball valve on the return line but it is all the way open. please see picture

2. i solved the problem with the back siphoning issue on the return line. the overflow i am using has a u tube. when i shut the power off, the u tube does not lose siphon...right away. but i let it sit overnight to test it and the next morning i checked the u tube and it lost its siphon. i dont know how much time it takes for the u tube to lose its siphon. if the power goes out for a long time (and it happend in NY last summer) and the u tube loses its siphon, the return pump will overflow the tank...then a nice flood in my basement. is the problem in the u tube? if i shut the power off for a few minutes or maybe even an hour, the u tube has no problem starting back up....its only for long periods of no power.

thank you for reading this and tia for any replies!!!

 

[mr_tee0419]

where is the u tube connected on the overflow?

 

[itzafugasi]

on the left side of the pic... u can barely see it if u look closely.

 

[mr_tee0419]

I am not familiar with overflows with u tubes, but I dont understand why the tank would overflow. When the power came back on, wouldnt the water flow into the overflow at the same rate of the return pump? I dont see how the tank could overflow unless there was an unmanagable amount of water being dumped into the aquarium. Maybe I just dont understand, but the basic principle of an overflow is that the water cycle of the system is dependent and consistent with the return pump flow rate.

 

[loganj]

I believe you will find that if you can raise the operating level in the outside box, your problem will be solved. I don't know exactly how your overflow is designed, but there should be a pipe extending up into the outside box. If you can raise the level of this pipe, or raise the level of the openings in the pipe, you will also raise the operating level in the inside box. If your U tube is losing siphon overnight, I'd also suspect a small leak in the outer box that is allowing the water level to drop to the point that air can enter the U tube. If this doesn't make sense, please don't hesitate to post again. If you can post some pics of the outer box and the drain design inside the outer box, I can make a more specific recommendation. I don't get the chance, due to my work, to get on here as much as I used to so I may be delayed in getting back to you. Feel free to PM me with a reminder to check your post if I can be of assistance.

 

[indy]

Your overflow should not fill up all the way, and you don't want it to. If it did it would mean your pump is supplying more than the overflow can handle. You want the overflow to be able to pull more water than the pump can push. This will keep the water levels balanced. Little air bubbles from the water drop are normal. If you slide the tube towards the center of the box they generally won't enter the tube. If your tube is losing its siphon, one of your boxes isn't holding water correctly, or your tube is cut too short on one side allowing air to eventually enter when the water level drops. Check to see if one side is right at the water line when you power down.

 

[itzafugasi]

After a night of powering the system down again, the u tube did not lose its siphon. i think water just evaporated and air got into the u tube, so i am no longer worried about that. everything seems to be working well. i was just concerned about the air bubbles in the overflow box but i understand now that it is normal.
loganj - i understand what u are saying, and i will try to play around w/ it and see what happends. thanks for the replies.... now its almost time for some live rock!!