Drill a siphon break in your return lines?
 

I have dual 1 1/2" return lines that empty down to my sump when the power kicks off, Could i drill a hole in the side of the elbows so the water that would blow out of it would stay in my overflows and would it work to keep the water in the pipes and not drain back to my sump?

not sure what you're meaning, siphon breaks are in the return line so you are not draining back from the display. Whatever water in your return lines between the siphon break and pump will still flow back to the sump.

LOL i was reading that right after i clicked post... didnt make much sense still having first coffee :)
My return bulkheads are below the level for my overflow so my display will drain about 2" to the bottom of those bulkheads... this is what im trying to avoid as its like 80 gallons or so.
http://img.photobucket.com/albums/v6...1ca/001-17.jpg
So if i were to drill a hole at the top of the elbow behing that bulkhead it would stop at the top of the bulkhead?

yours is like mine, they don't go "up and over" so there's no siphon when the pump is off, just a free flow line, so a siphon break hole won't help. Can you redo your return line within the overflow something like:
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| |___
|
|

I would said no. The water would still flow by gravity to the sump until the water level gets to bottom of return bulkhead

I would make an output piece with a couple of 30 deg fittings to bring the out put higher, then you also have the ability to adjust the flow. I had to do this to my 110g as the output was up through the overflow also. Stupid design IMO.

http://i589.photobucket.com/albums/s...0/IMG_4815.jpg

I used Loc-Line & Plastic Modular Piping. To raise the outlet just below the water line
http://www.jlaquatics.com/info/213/L...ar+Piping.html

Just notice that you have 1 1/2" return line, this may not help.

I was thinking this as a first option aswell, i need some kind of 1 1/2" threaded fittings and then try to either make a manifold of 3/4 Lok lines or use 45's as high as the overflows???
but keep it all black abs...

You should not be using ABS in any salt water tank, PVC pipe only.

From my ABS thread just a few posts down....

Well i went with the extentions :)
Im happy with em but im getting micro bubbles and i assume its them causing it so Ill have to glue them together... but i did a test and only lost 10 gallons and the ATO should cover that so i "should" be home free in a power outage :)
http://img.photobucket.com/albums/v6...h1ca/009-7.jpg

I dont understand this ? You dont want your sensors of the tunze in the display, keep them in the sump.

If your really concerned about drain back. I have always thrown in a check valve more so on the fact my skimmer is very sensitive to water levels and if the pump fails i don't want skimmate everywhere. The Wye valves are really good ones.

http://www.bulkreefsupply.com/store/...s/check-valves

oh no, Sensors in the sump... but the water level would go down there in the event... so when the power kicks back on the ato would fill the missing water till i got home and had to add salt...
My sump drains to the sewer so any extra water is just gone lol

Im looking into checks... I need to add 2 to my system, My skimmer is seperate to my return so he will be just fine with a water drop.
You need to be an engineer to do this hobby lol....its going on my resume lol

I wonder if they would be ok submerged? then i could put them into my overflows and not have to see them or add them too far down my lines?

I dont see why not they are sealed units and act on head pressure to shut them. What size of plumbing did you use i have a few sitting around.

That seems dangerous. I don't know if you realize the tunze will only pump for max 5-10 mins then cut off and go into a safety mode as a backup. 10 mins of pumping with the pump is not all that much water. I would re consider your plans here.

My returns are 1 1/2"

Wait so you're saying that all the water that flows down from the display during an outage is going direct to the city sewers? You have no room to handle the 10 gallons?

Any excess in the sump...2" give or take goes down the drain before it hits my floors... I used to run a constant drip with the freshwater like an auto water changer so now its a fail safe.... but maybe at the cost of a return pump in an outage...

Any well built sump can handle all the back flow. Why so complicated?

it wasnt designed for a 100 gallon refuge lol... that changed everything....
Instead of dealing with a total square footage im now dealing with the bubble trap at the end....and thats like 20 gallons a foot give or take x2 lol