New Tank

Hi,

This is my new Tank and Stand I made in the goal creating a reef fish tank... its a 78 gallon(US) Tank, the stand isnt done yes its full of water i'm testing and compacting before i stain & varnish. However before all that I would like to build my own sump. That being said I have a few queries. I'll be using an overflow box already understanding that its not the best way, however I don't trust my glass cutting skills nor do i wanna transport the tank 2 someone who can. anywho ive read around and .. believing ive understood the main idee behind it all, I have one question overflow .2.. swmp.. compartments.. heater... return pump how do i know what to use? if its 2 powerful wont it empty the sump? thats the major part i don't get(so far)
Thanks
Terry

Well Terry, first pick a flowrate you want through your sump. If I may make a reccomendation, try to aim for about 500-1000gph for a tank of that size. Then, measure the height from the bottom of your stand to the top of your display tank to get a head pressure rating to choose your pump. I'm going to guess your tank is ~5 feet off the ground. Then you need to pick a pump that outputs 500-1000gph at that head pressure. As an example I'm pretty sure Iwaki 20RT or 30RT pumps can do that. So now that you have a target flowrate, you need a properly sized overflow. If you're buying one commercially, get one rated for over 1000gph. If you're building one yourself, build it with at least a 1" drain pipe which can handle flowrates up to 1200gph I believe.

1" drain will get you 600gph flow rate.

Basically this is how an overflow works.
First step water enters the overflow and by gravity drains to the sump area below. Then it goes through the sump getting filtered and heated along the way (typically anyway). Next the water is pumped back up to the display where it displaces water from the display into the overflow and the process starts all over again.

Two things can go wrong here to cause a flood. First the overflow can get plugged or for a HOB style can break sifon or airlock. This causes the water in the overflow to fail to drain to the sump and the pump can pump too much water for the display to hold causing the tank to overflow. The second way for the tank to flood is if the pump fills the tank faster than the drain can remove water.

Personally if you want a refuge type sump setup I like around 600gph flow through it. I have set all my tanks up with a single one inch drain and a mag7 return pump. I use powerheads or closed loops to get better flow inside the display tank.

Really? I thought 3/4" was 600gph and 1" was 1000gph... I was way off

Thanks guys

you can push 1000gph through 1" but only with a suction effect caused by the vacum created by the falling water. If you set up this way you have to be extremely careful dialing in the return pump as it is easier to overrun the drain this way. IME its easier to add drains if you want more flow.