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View Full Version : Small pump not effected by gravity?


d2mini
12/09/2012, 03:13 PM
I'm tweaking my AWC setup and my freshly mixed saltwater container sits at a higher level than my sump. The little Rio 180 pump that I just bought to use is apparently effected by gravity because even when the pump is not running, water is still flowing into my sump. Does anyone know of small pumps that cut off the flow of water completely when they are not running??? :confused:

Epicreefer
12/09/2012, 04:06 PM
Your getting a siphon when the pump turns off. You need to find a way to break the siphon somehow because all aquarium pumps will do this if your source water level is higher than the out. There are pumps that won't do this but they aren't something you want to use on a tank. When pumps aren't running the water flows around the impeller and out like the pump isn't there and it's just a standard hose siphon. The easiest way is to add a T at the high point of the line. Either reduce down to a small diameter and return that water back to the supply tank, when the pumps off air will fill the lines and it will stop siphoning. Or a backwards check valve, closes under pressure/ water flow and opens to let air in under suction like when the pump stops and the siphon takes over. Hope that helps.

d2mini
12/09/2012, 04:17 PM
Yeah, i could easily add a T. I have a T john guest fitting and I'm using 1/4" water line. I guess the only downside is it will probably take twice as long to fill the sump. I've heard of check valves failing so the T would probably be the safer solution.

zakstrong
12/09/2012, 04:42 PM
the easiest thing to do is drill a hole in the return line to the display slightly above the water line. then when the pump turns off it will suck in air and kill the siphon

Epicreefer
12/09/2012, 04:45 PM
With 1/4" the check valve wouldn't work well. They do fail under water plumbing due to biofouling but this would be "air plumbing" and they don't fail. This is the only situation where I would ever use a check valve because it's the only time they don't fail and it's not a critical system component like on the tank return pump.

d2mini
12/09/2012, 05:01 PM
the easiest thing to do is drill a hole in the return line to the display slightly above the water line. then when the pump turns off it will suck in air and kill the siphon

It's not going to the display. The water line is running from the saltwater mixing tank which is high, to the sump which is low.

zakstrong
12/09/2012, 05:14 PM
then drill the hole in the hose slightly above the water line in the mixing tank

d2mini
12/09/2012, 07:15 PM
Well, I may have to. The T idea was a big bust. 100% of the water was shooting out of the open end on the T with none of it traveling through the water line to the sump. :(

azjohnny
12/09/2012, 07:17 PM
I am thinking the saltwater is siphoning due to the mixed saltwater tank is higher and gravity is your foe. Is there a way to lower the mixed saltwater tank so it is closer to the level of the sump.

Epicreefer
12/09/2012, 09:27 PM
if the T didnt work then yea drill a tiny hole. Start with 1/32 if you have one and go bigger if it doesnt work. also it doesnt have to be at the high spot, just somewhere between the water level of the reservor and the high spot so it gets air while the water would be traveling up.