dano February 9, 2009 Share February 9, 2009 I don't have a good understanding of how the overflow works and I have issues with both my tanks. MY home tank used to be fine but for some reason, when I turn off the return pump for cleaning/water changes/power outage, my sump overflows. It did not used to be this way - it would rise up in the sump but still stay a couple of inches below the top - and I think it has something to do with the plunger thing-a-majig (what is the proper term?) in the overflow. My office tank has a problem with the plunger thing-a-majig that when ther is enough water in the sump to cover the return pump, the plunger raises above the top of the tank and I have to lift up the plastic cover on that part of the tank so as not to push down on the plunger (creating noise and bubbles). Any ideas/explanations appreciated. Thanks. Dano Link to comment Share on other sites More sharing options...
jason the filter freak February 9, 2009 Share February 9, 2009 your stand pipe/intake in your overflow needs to be higher Link to comment Share on other sites More sharing options...
DJBoy98 February 9, 2009 Share February 9, 2009 Also the return flow. W/o a check valve, it will cause a reverse flow and suck water back to the tank as along as the suction isn't broken. Link to comment Share on other sites More sharing options...
zygote2k February 9, 2009 Share February 9, 2009 Put the return flow in with loc-line. That way you can adjust it so it doesn't create a siphon of its' own when the power goes off. Like the aforementioned post, a check-valve on the return also helps. Link to comment Share on other sites More sharing options...
dbartco February 9, 2009 Share February 9, 2009 I would not mess with check valves, they are false sense of security. They will fail eventually. Make sure your returns are not that deep, and will break the siphon before the sump overflows. I am assuming you do not have a drilled tank, and this a u-tube overflow or something? Is there adjustments in in the box making it higher or lower? Link to comment Share on other sites More sharing options...
zygote2k February 9, 2009 Share February 9, 2009 I would not mess with check valves, they are false sense of security. They will fail eventually. You can use check valves as long as they are "true union check valves" which allow you to remove and clean them on a regular basis. You should not use them as the only way to eliminate backflow. You should use them in addition to other methods. Link to comment Share on other sites More sharing options...
quazi February 9, 2009 Share February 9, 2009 Depending on your return type, drill a hole in the return line just below the water line. It will break the siphon when your pump stops. Of course, you need to keep it clean... Link to comment Share on other sites More sharing options...
dano February 9, 2009 Author Share February 9, 2009 (edited) Thank you all for your help, though I'm still not understanding it... my home tank which overflows the sump... has an overflow compartment in back left corner in which there is a tube and a float which goes up and down on the tube. As far as I can tell, the water flooding the sump is coming from this tube and not from the return flow to the tank... though I will check that. When I get home tonight I will try to give it a better inspection to see if I can figure anyting out. Thanks again Edited February 9, 2009 by dano Link to comment Share on other sites More sharing options...
DJBoy98 February 9, 2009 Share February 9, 2009 Unplug your pump and watch the action.. You'll see what we mean. The pipes under the water will continue to reverse flow until the water levels drops that level. You'll hear a gurgling noise and see that suction has been broken and the back flows have stopped. Link to comment Share on other sites More sharing options...
zygote2k February 9, 2009 Share February 9, 2009 For the office tank- if the float rises up and down and makes noise and bubbles when in normal operating mode, you're running more water through it than it can handle. If you have a ball valve on the return pump, you can throttle it back so the float stays at a constant level and doesn't make noise or bubbles. Link to comment Share on other sites More sharing options...
Origami February 9, 2009 Share February 9, 2009 Dano, if you can post a picture of your overflow, it would be helpful. As for the return: If your return is coming into the tank below the water line (that is, it's not dropping through the air onto the surface of the water), then there is the risk that, when the return pump stops, of the return line siphoning the water out of the tank into your sump (unless there's something in the line that prevents this reverse flow such as a check valve). (Check valves, by the way, can and do fail, so if you're dependent upon them, someday you'll likely be regretting it.) Imagine it this way - you have a tube full of water coming from your tank going to your sump - that's your return line. Normally, the water is flowing from your sump up to your display because the pump is operating. When the pump stops, however, it may allow water to flow through it the other way (most do). In this case, you've now got a siphon situation and water will now flow from the display to the sump. Most of the time, though, we drill a small hole (normally just below the surface but sometimes above) that functions as a siphon break. In this case, when the return pump stops, water is siphoned back to the sump until this hole is exposed. Once exposed, air is drawn into the return line and breaks the siphoning action, stopping the reverse flow. We try to keep this hole clear because, if it gets clogged with debris or algae (or even blocked by a snail), the preventative measure against siphoning is defeated. It's unclear to me, however, if this is your problem by the way you're describing your setup. I'm not sure that I can accurately picture this thingamajig with the float that you're describing. That's why a picture would help. Link to comment Share on other sites More sharing options...
Origami February 9, 2009 Share February 9, 2009 For the office tank- if the float rises up and down and makes noise and bubbles when in normal operating mode, you're running more water through it than it can handle. If you have a ball valve on the return pump, you can throttle it back so the float stays at a constant level and doesn't make noise or bubbles. Rob, you seem to be aware of this float thing. Does this float block the vent into a durso-like drain or something, thereby causing a siphon on the drain side that can handle higher flow? Link to comment Share on other sites More sharing options...
Coral Hind February 9, 2009 Share February 9, 2009 Dan, If you need help give me a call. I will make the long 3 mile drive to come take a look at it for you. Link to comment Share on other sites More sharing options...
zygote2k February 9, 2009 Share February 9, 2009 Rob, you seem to be aware of this float thing. Does this float block the vent into a durso-like drain or something, thereby causing a siphon on the drain side that can handle higher flow? On the older style of internal overflows from AGA, there is a float that rides up and down in the drain tube of the overflow. If there is too much water going through the overflow, it will back up causing the float to bob up and down rapidly resulting in gurgling and intermittent flow to the sump. The new style has an adjustable riser with a vent and an upside down "U" shaped piece for straining the water into the drain pipe. If you are running too much water thru this new style, it will make lots of gurgling noise too. Link to comment Share on other sites More sharing options...
dano February 10, 2009 Author Share February 10, 2009 Thanks to all for the explanations and offers... when I get a chance I will examine all the processes more carefully and post what the issue is/was (hopefully). I still haven't figured out how to post a picture so that may have to wait. Thanks again. Dano Link to comment Share on other sites More sharing options...
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