unplanned water change (also posted in reef tanks)

leigh

Active Member
well, detroit edison, in their infinite ineptness, has managed to black out isolated areas for short time periods in addition to the thousands of customers they still have yet to restore power to since last weeks storms. apparently some time this afternoon (i think about 3 hours ago based on the time my clocks are blinking) my power was out for an unknown period of time. of course, no big deal, i wasn't even home. however, i came home to find half my sump on the floor. this surprised me. see, i figured with a power outage my pump would go out, the water level in the sump would rise (thus the half full sump) no biggie, then when power comes on, pump will kick on and the sump/overflow/return pump cycle would start again. from what i can tell, however, during the period when the power was out, i lost suction in my overflow u-tube, and so when the power went on, half my sump got pumped into the main tank with no where to go, thus overflowing. i know it was the main tank that overflowed, not the sump, based on where on the floor i found water (and based on the evil look my gigantic hermit crab in my sump was giving me). so my question is, why'd i loose suction? if everything stops, hypthetically, shouldn't suction in the u-tube to the overflow still remain?
thanks!
-leigh
 

leigh

Active Member
nope, and you're right i think that's the problem. i always figured so what if i back siphon, that's why we only keep the sump half full. i gather though if it back siphons too fast that can cause the water level to drop rapidly enough to allow some air into the u-tube thus breaking the siphon?
-leigh
 

ian

Member
When I bought my system I was advised to add a check valve (about $3.00) and if the water starts to back siphon the valve flips shut and prevents the "flood". Although it has never happened to me I hear that it will often siphon until the tube can't reach any more water.
Oh well we live and learn right? Maybe it is time to get a check valve!
Great Luck
 

broomer5

Active Member
Back siphoning and losing prime in the U tube are normally unrelated events.
See your other post ;)
 
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