Completely closing valves downstream of a pump

Exactly right there is no substitute for safety like redundancy. I only have one return pump or a recirc. pump so I don't exactly have any redundancy. But I guess I could put a couple of powerheads on the other strip with my lights. I even thought about putting a float switch in the sump hooked up to a relay that would cut the return off if the water got to a dangerous Low Low level. But that is when I hook my MicroLogix up.

 

Another problem that I have is that when I turn the pump off, it creates a powerful "reverse" siphon going out of my tank, through the pump, and into my sump. I guess I'll have to close the valve and turn the pump off to be completely safe.

 

You should have an anti siphon hole on your return line but mine is so low in the tank that a ton of water gets siphoned back down, I was pondering about using a check valve in the return line.

 

stay away from check valves.. more water in the sump isnt necessarily a bad thing..

 

Glad you answered that. I wondered about using it, but i haven't read a whole lot of talk on her about them.

 

your sump should be spec'd to handle the reverse siphon during a power outage. have you tested to make sure it siphons and then gets air at some point to stop the siphon before it overflows the sump?

 

and i guess i dont understand pump head shut off. i thought the pump shuts off at a certain head pressure. if you closed the valve it'd have 100% pressure so it should shut it self off right?

 

I dont think it shuts off necessarily. It just cant pump any more water, which would be just like closing the valve..

 

yeah your pump would have a "Max-head" rating which is how high it can actually push water. water gains like 1 psi for every ~2.3 feet so at a certain height the head PSI is greater or equal to that of the pumps output capacity so it just sits there "dead heading"

 

ah, yeah makes sense. thanks.