not really a sump but part of the filteration

[whodini]

i have a 90gal w/ heavy bio-load so have battling high nitrates. with silver dollars will eat all the plants if it were to be planted. So got an idea from my lfs ;
heavely plant my 30 gal tank and use my fluval 304, leave output in the 90 and install the input in the 30 , and connect the two tanks via a siphen hose.
I'm a paraniod about my tanks and if something is going to happen, it'll happen when i'm at work!!! My question is ..
Does anyone have/ideas of a DIY water level control system ?
Like if the power goes out and the siphen keeps siphening water and over flowing my 30 , or something gets stuck in the siphen tube and the fluval sucks all the water out of the 30 and overflowing the 90. or any variation happening.
i just need to know how it should be setup , and how much lower is the 30 gal then the 90gal water levels.
I would be setting up the 30 gal beside the 90gal

 

[dskidmore]

If the two tanks are set up so the tops are level with each other, the siphon will stop when the pump stops. There will be no problem in the event of a power outage.

If one tank is lower than the other, the upper tank should get an overflow box. The overflow box will only pass through water above a certian water level, so it will pass to the lower tank exactly the same amount of water as is getting pumped back up. If the power goes out, the water level in the upper tank will fall to the level the overflow box is set to, and stop flowing. A properly set up box will not loose siphon when this occurs, and start right back up again when the pump turns on.

You are describing a refugium, set up for nutrient removal. You might try doing searches on refugium for ideas.