Gravity feeding frag tank from main display

[Boxofpurplerocks]

Question for you all: Has anybody set up there tank to be gravity fed from there main display, which then drains to your sump? Basically what I’m thinking of is having my overflow from my main tank drain to my frag tank (tank will be lower in elevation) as the main flow/return, then from there drain to my sump. Attached is a rudimentary pic. What is the downside to this? In my mind it’s free flow without having to add a second pump to my sump.. what am I missing here? Thanks I’m advance!

edit: to clarify, my tank is already drilled with an external overflow which drains to the sump underneath. What I’m proposing is instead of draining right to the sump, my overflow drains down to the frag tank, then the frag tank drains to the sump.

 

[lapin]

I dont see any problems. I have never done it.
You will have to drill your main tank or use some sort of reliable overflow

 

[Boxofpurplerocks]

Should have clarified.. my main tank is already drilled with an external overflow which goes right to the sump. So what I’m proposing is instead of it draining to the sump, it drains to the frag tank, which then drains to the sump.

 

[clowndog]

Should have clarified.. my main tank is already drilled with an external overflow which goes right to the sump. So what I’m proposing is instead of it draining to the sump, it drains to the frag tank, which then drains to the sump.

Would suggest to keep it simple. Every overflow carries its own risk of overflowing. Why not to have a separated pump from sump to your frag tank with its own drain back to sump, and leave the main's drain/pipes to sump as it is? Both frag and main drain directly to sump. This way, you can control the flow rate individually pending on the different needs of frag and main, and create kind of redundancy for protection. Otherwise, if you connect all three tanks together with one set of drain, any segment main/frag or frag/sump goes wrong, the whole system mess up.