sump back syphon question (with pics)

[smokymcjoe]

my tank is drilled in the bottom, with a weir corner overflow one side and vertical return spray bar the other

.

the bar is drilled as you can see, with the top above the water level.

however when the pump is off is still back syphon's into the sump.

i have a check valve on it, but as im sure anyone using will tell you, it doesn't seal but slows it down heck of a lot.

i just have sponge in the top so thought it was because the sponge was blocking the holes.

so i took the sponge out, yet it still fills the sump. (slowly because of the check valve,) but the water level in the sump still rises.

is it because i had no lid on the standpipe thefore too much air is being brought in,. or is it because of the check valve slowing it down but preventing it from stopping?

im sump'd i mean stumped lol,

any help much appreciated because i know i would sleep so much better knowing there was no chance of flooding my house if the power went while i was asleep or out.

 

[beex215]

thats a regular syphon. your whole tank will train or at the lowest hole. you need an overflow.

 

[cichlid2006]

your whole tank will drain with that.
do your return as un-drilled vertical pipe with a 90 degree bend at the top and then attach a horizontal spray bar so the syphon break is the spray bar. thats what i have done with my returns, although they are drilled into the rear of the tank but i have a slightly raised spray bar which stops back syphon by becoming the syphon break. while your first hole acts as your syphon break the water will still go back into the sump and because your holes go all the way down the height of the tank it will drain the whole thing eventually, say in a 24hr blackout. i know we rarely get power cuts for more than an hour or two in the UK but you should plan for worst case.
i do not have non-return valves as was planned but i dont trust them enough anyway. if you design your return right you dont need them anyway.

instead of coming from the rear like mine your return would attach by vertical pipe but would essentially look the same and would only allow about an inch of your tanks water to drain to the sump.
another alternative is to plug that return and go for a hang on return design, which would basically look like a regular canister filter return.
Hope that helps.

 

[smokymcjoe]

thanks for the responses.
and thanks for the pics cichlid2006.

that was pretty much what i was thinking.

but i had read this on a reef forum

Watch out for siphon effects! If your return line is underwater in the display tank, water will siphon down the return line when the pump turns off (due to power outages, pump failure, etc). Water will siphon out of the main tank into the sump until the water level in the main tank drops below that of the return line. If the return line is just an inch or so below the water line, this may not be a problem. With a return line plumbed to a vertical spray bar however, the entire tank could drain due to this effect. The possible volume of water siphoned in this manner can be reduced by drilling "siphon-break" holes in the return plumbing just below the water line. These will cause air to be sucked in with the siphoning water, breaking the siphon. These holes should be fairly large and should be checked often for blockage by encrusting organisms.

but in the back of my head, im thinking surely that wont work, and it doesn't lol.

thing is i dont want more piping visible, so i think ill put a 90 degree bend then a small piece of pvc to make a return nozzle.

bloody sumps lol.


thanks for the advice. much appreciated.

 

[cichlid2006]

Make sure you block the end of the nozzle with egg crate or mesh or melt the end so it narrows the exit because if the pumps stop you dont want your fish taking a trip.

 

[smokymcjoe]

Make sure you block the end of the nozzle with egg crate or mesh or melt the end so it narrows the exit because if the pumps stop you dont want your fish taking a trip.

lol yeah, i intend to melt the end,. but none of my fish would fit down a 1" pvc. Come on this is MFK who fish fish less than an 1" unless they're feeders lol.

 

[cichlid2006]

lol yeah, i intend to melt the end,. but none of my fish would fit down a 1" pvc. Come on this is MFK who fish fish less than an 1" unless they're feeders lol.

lol, i do and they arent feeders, about 35 buenos aires tetras.