QuoteReplyTopic: durso Posted: February 06 2007 at 8:08pm
came home tonight to air bubbles and an overflowed tank.... i have a mag 12 on my 90. if the durso hole gets salt creep in it and restricts it will that cause it to overflow?
yeah.. kinda a bit much i know... wish the drain in these was a bit bigger. i had to slot the teeth on the overflow to keep up.. maybe i will throttle the pump back a bit.. i still have my dart to move lots of water
Say the water level drops below the bottom of the durso opening allowing air to flow into the top of it. For example during a power outage or twin dursos at slightly different altitudes. If you have a durso with no hole in it(or it is plugged) when the water level rises there is air trapped in the top of the durso preventijng full flow through the durso. If you have a small hole in the durso the air escapes allowing the water level in the horizontal section of the pipe to rise increasing water flow. If it were to rise over the hole you would have a full siphon.
Mike's right. A plugged airhole on a durso will not result in a flood. It'll result in a full syphon which empties the overflow box causing a loud gurgle which breaks the syphon and the box fills. Once it reaches the top of the durso it starts draining and forms another full syphon which repeats ad-infinitum. When that happens (and it does happen to me often, 'cause I don't routinely clean out my airhole*) I come home to a tank that sounds like a flushing toilet.
Perhaps a snail plugged the drain, then ran away from the crime?
i'll have to dust for snail prints.... seen some things on csi that will help out. im just scared to go to work tomorrow and have this thing flood again.
That is good theory but I'm not sure it could happen in practice. It would take a very slow flow to allow air to build up like that and I don't think the salt creep forms a perfect seal.
Ya, I was thinking more like after a power failure where you lose siphon or with multiple dursos in the same overflow. I think you are right that saltcreep probably doesn't usually form a complete seal.
I can see what you're thinking Daren, but in practice the water falling down the drain side pulls that air with it. You can set up a durso with no hole what-so-ever and it will just cycle up and down going from full vacuum to nothing.
I am sure you are right. What do you of the following scenario? The people who have the upside down "U-tubes" on their HOB overflows. How do they get air in the top and lose siphon. Do you think the less turbulent laminar flow makes the problem better or worse?
The bubbles in the top of the overflow syphon are due to low water velocity (i.e. U-tube is too large in diameter). There has to be enough velocity to carry any entrained bubbles down the downward side of the syphon.
so could forcing 1000 gph down the 1" drain be a problem? the thing thats weird is i came home to the water right at the top edge and the pump blowing bubbles. all i did was turn off both pumps<closed loop and return> and then turned them back on after i cleaned the durso hole out... i had the problem with the flushing before i drilled the hole so i follow whats being said but have no clue why it flooded.
ill have to check that. i think its pretty close to level. i was just going off the durso drain site, for the plans. so maybe my durso could be too long? thanx for all the help jon, mike, and darren
If the elbow on your durso is almost level with your tank, it'll never really "work" right. It needs to be a couple inches below the tank water level. Good luck!
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