I am planning a 75 gal tank with a 29 gal sump underneath it. I was thinking a mag pump or gen-x. How big do you think it needs to be?

What are your goals for the tank? A mag7 would prolly work at a minimum.

gwen right.. a mag 7 or 9.5 would probably be good, but it depends on what you need, and what your overflows can handle.
the pump rate has to be less than your overflow rate.

Is there a certain formula for calculating the overflow rate?

I dont have the tank yet, but I know it has dual overflows. dont know how big the bulk heads arethough.

Is there a certain formula for calculating the overflow rate?
that i do not know.
i would check with who makes the tank/overflow box.

Mine was calculated on a 1" bulkhead dumping 600 gph into the sump, with 9" of linear overflow length. I have two 1" overflow bulkheads for a total of 1200 gph. I have a Rio 2500 pushing about 490 to 500 gph back up. All of the calcs were based on the calculators available on the side bar of the main page at www.reefcentral.com. Here is a quick link to both of them.

Drain Line Calculator (http://www.reefcentral.com/calc/drain.php)

Head Loss Calculator (http://www.reefcentral.com/calc/hlc2.php)

The head loss calculator tell you the approx GPH after taking all of the piping bends and vertical flow. In my example the RIO pushed 748GPH, but due to head loss, I only get 490-500 out of it.

I think most of the bulkheads on the 75 gallon tanks are 3/4" and typically you get one supply and one return bulkhead. I would suggest you look into the different methods of handling your overflows and returns, There are things called Durso's, and Stockman Standpipes (both are modifications from the standard issue tank overflow piping) that cut the noise of the tank down tremendously. I just got mine running (all holes and piping from scratch) and it is quieter than the fans on the PC I am typing this on. You can see what i did in My Tank Journal (http://www.reefcentral.com/calc/hlc2.php).

I have done alot of research and I am willing to answer any questions I can, just let me know. Good luck and welcome to Talkingreef!

Great stuff- thanks!! I just need to get someone like you to teach me- I'm afraid if I try, I would get all confused and never figure it out-- one day, maybe one day.

Thanks for the info. I may be looking you up when I start putting it together.

christensonjes - Welcome to TR!

Lots of luck setting up your new system.

I'm not sure about the brand of the pumps that you have available to you over there, but I would suggest trying to get a 4-5X turnover through your sump. For the rest of the flow, you should aim at getting it within the display, either through a closed loop manifold or powerheads within the main display, or a combination of both.

Once you find your GPH try a Mag Drive. I swear that thing literally has no head loss for a return. Their just massive and extremely silent.

duane, thanks for the info, it answered all my questions. thanks again for your help :)

I agree with posts above, a mag 7 or 9 would be perfect and you could always throttle the outlet to the return lines a bit if your overflows can't keep up.

chris, way back in post 2 gwen asked what the goals of the tank are?
this has to answered when u can buddy! all the products & formula's given are great, & thanks for posting up guys, but without knowing if your going to keep clams vs gonia how can we advise accuately what types of flow rate in the main or sump. giving models that could handle the overall volume wilst helpful doesn't answer this question head on with simple things like bulkhead & pipework sizes, stand height ect ect, i say yet! cause once u do have the spec u need, u'll prob find all the answers are compltely relevant

Hi, Just sitting here reading all your post about the seventy five gallon FOLRO. I am at the point of just reading all I can and have the seventy five gallon glass aquiriam and need directions of how to set the overflows into the sump system. I would appreciate any help that any of you can help me with.

Phil