View Full Version : Syphon fed sump
I was thinking about having a sump being syphon fed rather than gravity/overflow fed as i dont want to drill my tank.
What i want to know is how to calculate how much flow there would be going into the sump so i can match up the return pump as close as possible. Obviously i know this depends on the size of the pipe and gravity. I just wondered if there was an easy way to figure it out without seeing how long it took to fill a 25ltr drum!!
Dive Master
11-02-09, 14:04
The overflow system you are referring to is all dependent upon pump size too.
For me, I have the tunze. As this is flowing into a sump dsb and ecosystem, I needed a gentle flow. Thus, the overflow is rated about 2-3000 lph but I'm actually pumping back 700lph.
Feeding a sump with using a syphon is asking for a flood - it'll happen sooner or later for sure!
Really, you need to gravity feed it!
John
I think i need to clarify on my intended setup!
My sump feed will only be 1/2-1" below the display waters surface, with the pipe going up and over the edge of the tank then down into the sump. The return pump will be in the sump, hopefully returning the water to the tank at the same rate that it is siphoning out....
A flood situation will be avoided in the way that if the return pump fails then only the top 1/2-1" of display water will siphon out. My sump would be designed to handle the extra water should this happen. Either that or i will create a corner weir with the sump feed taking water from here and the return pump forcing the display to overflow into the weir.
All i needed to know is how to work out the required flow rate of the return pump to match the flow siphoning out of the tank....
peterdavies
11-02-09, 17:51
if the sump is at the same level of your tank, you need to be sure the return pump isnt faster than the syphon tube. As long as the return pump is slower, water will only syphon as the tanks water level becomes higher than that of the sump, and should the pump fail, the syphon will stop also. this assumes your having the sump on a shelf or something at the exact same height as the tank. The water level with the return pump off must be the same in the sump and the tank, when the pump is on, the sump will have a slightly lower level.
But if you lose the syphon (air gets in somehow) then the return pump will continue pumping into the main tank and that will overflow. Or if the inlet to the syphon gets blocked then the pump will then run faster than the siphon, and the tank will overflow. Or if you have a power cut, the pump will stop and the siphon will continue until it breaks, then the power comes back on and the tank floods.
As pointed out, it's a flood waiting to happen. If you use an overflow box then the siphon remains when the power stops and the flood risk is reduced. Also the overflow box only flows as much as the return pump puts into the tank, and that's all it does (provided the box is rated to the correct flow for the pump.
If you do choose to try and match a pump to a syphon, then you're either very brave, very trusting, or very daft. I mean this in the nicest possible way of course, and I hope you'll see the error of your choice. ;)
peterdavies
11-02-09, 18:09
if he has the sump raised so the water level is the same as the tank as he suggested was the case, the only problem is if the syphon breaks, which will cause the sump contents to be pumped into the tank leaving the sump dry. The syphon will stop if the pump fails as the pressure will be equal on both sides if the water level is the same. Im just tryin to suggest it would be possible, but still an overflow box is surely better as it will also take the crap off the water surface. you can also hide the sump below so its not in an obscure place.
The sump would be in the cabinet below the tank....I would probably fit a float switch in the sump to the pump so that should the siphon break for some reason and the pump continues to run then the pump would auto switch off when the sump reached a certain level preventing the tank from overflowing too....The only way i can see this situation occurring though is if as viking said, i have a power cut and then power returns...
Maybe i should post a illustration of my intention then wait for your criticism!! No one has yet to answer my original question though!
If for example i know that approx 1500lph will siphon out a 16mm eheim tube i could easily match that to a 1500lph pump and balance the two flows out using restrictor valves on both feeds....how do i work our the flow into the tank though. Im thinking it's going to have to be the the bucket test now....
Oh, i dont have room behind my tank for an overflow box by the way. Hence why i haven't considered using one... :)
peterdavies
11-02-09, 18:35
Totally misunderstood what you were getting at - sorry
Could you seal the sump up so it is like an external filter - just an idea make of it what you will
This isn't going to work, you'll never get the flow through your syphon exactly balanced by the return pump. Any difference, however small, in either direction will result in a flood sooner or later.
Won't work - you'll either fill the sump quicker that it empties and continually lose the siphon, or else return quicker than the siphon and burn the pump out - back to the drawing board (lets be honest, if it was that simple, would we all not be doing it ;))
The only way i can see this situation occurring though is if as viking said, i have a power cut and then power returns...
Not exactly an unheard of scenario is it? What happens it it does that while you're on holiday?
No one has yet to answer my original question though!
I kinda did - I don't think it's a goer! :D
If for example i know that approx 1500lph will siphon out a 16mm eheim tube i could easily match that to a 1500lph pump and balance the two flows out using restrictor valves on both feeds....how do i work our the flow into the tank though. Im thinking it's going to have to be the the bucket test now....
In the real world you can't balance the two - partial blockage of the syphon pre-filter, partial blockage in the pump's pre-filter, gradual build up of detritus in the pipework, a snail in the wrong place, etc, will all adversely affect your carefully balanced system.
Oh, i dont have room behind my tank for an overflow box by the way. Hence why i haven't considered using one... :)
Then I'd drill the tank!
I know it sounds fine in theory - if it was fine in practice everyone would do it - who wants to risk a broken tank by drilling it? There are tried and tested methods - dursos, dual standpipes, etc. Trying to balance inflow and outflow is a recipe for a flood.
John
I'll sack the idea and do without a sump then :( Sure ive seen other people do it this way but maybe im mistaken.........
Sure ive seen other people do it this way but maybe im mistaken.........
I think you are :D
I'll sack the idea and do without a sump then :( Sure ive seen other people do it this way but maybe im mistaken.........
You can have a sump but bt using an overflow weir see HERE (http://www.melevsreef.com/what_sump.html)
Cheers mate,
The system he describes is how i was thinking of doing my setup but obviously without a big bulky overflow box. I guess one could be made by bending some eheim tubing into a w shape, should work in theory......
One thing though, nearly everyone said my original plan would fail with a siphon down to the tank with a matched return pump and a level controller to prevent flooding. Well after looking at the the tunze compact kits they work exactly this way, the only difference being is a powerhead on the siphon line to increase flow rate...Am i wrong?
As it is im now going to try the sumpless/skimmerless route and i can come back to this should i not be able to maintain healthy parameters :)
An DIY overflow weir don't have to be big and bulky
But you need the skill to make on
http://i142.photobucket.com/albums/r97/wave-ace/Marine/nanowier.jpg
http://www.ultimatereef.net/uploader/2008Q1/small wier.jpg
I only have about 1-2" between the rear of my tank and the wall so thats not really enough room.... I could make one but the flow wouldnt be that huge and the effort might be wasted. Like i said, some 1" eheim tubing bent into the same shape may work but its off the drawing board for the time being...I'll experiment when i have a moment!! :laugh:
Dive Master
13-02-09, 15:35
I ran a similar system when keeping tropicals some 8 years ago.
When I went on holiday for a week, there was evaporation and thus the water level sank below the syphon line.
The pump was probably running dry for a couple of days and I'm lucky that there wasn't any other problems!
Appreciate that you have limited space, but to have a sump system you really need to consider drilling the tank or trying to fit an overflow box in somehow.
I can't see any way around your problem!
An DIY overflow weir don't have to be big and bulky
But you need the skill to make on
http://i142.photobucket.com/albums/r97/wave-ace/Marine/nanowier.jpg
http://www.ultimatereef.net/uploader/2008Q1/small wier.jpg
the measurement of this weir is less then 2" and was capable of handling about 1000L/h
I ran a similar system when keeping tropicals some 8 years ago.
When I went on holiday for a week, there was evaporation and thus the water level sank below the syphon line.
The pump was probably running dry for a couple of days and I'm lucky that there wasn't any other problems!
Appreciate that you have limited space, but to have a sump system you really need to consider drilling the tank or trying to fit an overflow box in somehow.
I can't see any way around your problem!
As previously stated in the thread my return pump would be controlled via a float switch/level controller so if the tank got too high or sump too low the pump would switch off preventing it running dry/tank overflowing. The siphon tube would have an air break in it so that the syphon would break should the tank drop too low and it would also have an auto top up to combat evaporation. The only thing that wouldnt work on this setup is that you would manually have to restart the syphon should it stop. I guess this is why the tunze compact kits have a powerhead on the sump feed tube.
the measurement of this weir is less then 2" and was capable of handling about 1000L/h
hmm...interesting. I may have to give fabricating one a go when i have some spare time. Still want to try the sumpless/skimmerless route first though especially as my stock is going to be so low...to start with anyway :o
Its also more of a maintenance thing for my other half. I work away for a couple of months at a time so if i can get the tank stable enough that all she has to do is water changes/top ups, and feeding then all the better....
is the tank already set up mate?
is there a reason you cant put a weir in (sorry if you've already said, i did breeze over the thread, but didn't see it)
LOL! No its not set up yet, empty tank is sat in my conservatory awaiting the nice builder to move a door form the corner where the tank is going to go! I also have to fabricate a custom hood for it to replace the crappy broken i got with it and also locate some cheap mature LR.....
The reason for no weir is i dont want to drill the tank and the tank would be too close to the wall to fit an overflow box...i think....Oh its a trigon 190 by the way...
On a different note, hows your set up coming along? Up and running with those triggers in it yet?
The reason for no weir is i dont want to drill the tank and the tank would be too close to the wall to fit an overflow box...i think....Oh its a trigon 190 by the way...
On a different note, hows your set up coming along? Up and running with those triggers in it yet?
howcome you dont want to drill the tank? is the trigon 190 a corner tank?
havn't got the setup running yet :rolleyes: getting there slowly, but triggers are eating me out of house and home in their holding tank :laugh:
howcome you dont want to drill the tank? is the trigon 190 a corner tank?
havn't got the setup running yet :rolleyes: getting there slowly, but triggers are eating me out of house and home in their holding tank :laugh:
Just didnt want the risk of breakage but more importantly, the chance of it leaking when im not there....:oops:
Your triggers will think thats their permanent home soon enough...:laugh:
One thing though, nearly everyone said my original plan would fail with a siphon down to the tank with a matched return pump and a level controller to prevent flooding. Well after looking at the the tunze compact kits they work exactly this way, the only difference being is a powerhead on the siphon line to increase flow rate...Am i wrong?
Um, yeah! ;)
The Tunze outlet (http://www.tunze.com/149.html?&L=1&C=GB&user_tunzeprod_pi1%5Bpredid%5D=-infoxunter005) IS an overflow box. It is not a full syphon direct to the sump but is a syphon over the top of the tank to a small (tiny!) reservoir on the outside of the tank (the other half of the overflow box). The level in the reservoir is dictated by the level in the main tank. As water is pumped into the tank, the water level rises in both the tank and therefore the opposite side of the overflow box, which then overflows by gravity into the sump.
It is a fine but crucial difference - it is most definitely not an unbroken syphon to the sump.
Re attaching powerheads, people attach the venturi feed of a powerhead to the overflow box, not to increase the flow, but to draw out any bubbles that can accumulate at the top of the overflow box's syphon. If allowed to accumulate over a period then the syphon will eventually fail.
I understand that the Tunze 3155 level controller is an auto top-up mechanism and is not to there to switch the return pump off to prevent flooding, but is present to prevent too much top-up water being pumped into the system in the event of the infra-red sensor failing.
FWIW the simpler you make it the less prone to failure it is going to be. It is not unknown for float switches to stick on/off, or for snails to cause a malfunction. If your system is not set up, I would definitely drill it and use either a durso, or preferably, a dual standpipe arrangement.
HTH :)
John
:o Well that's me well and truly told.....
The compact kit description and related products page including photos has no mention of an overflow box at all of any description... but hey, im a relative noob to all this hence all the question asking. :confused:
http://www.tunze.com/149.html?&L=1&C=GB&type=&user_tunzeprod_pi1[predid]=-infoxunter004
I like to sometimes think 'out' of the box and when someone tells me it cant be done for 'this' reason, and i can see a way around said problem, i like to challenge the idea. I also don't like just the, 'it wont work' answer. I like to have a full explanation as to why it wont work and why the obvious fixes to the flaws wont work either other than, because its a pain in the arse. :scratchhead:Because that then drives me to find a solution and prove the 'it cant be done' brigade wrong. If im wrong and it turns out they were right then i will hold my hands up and surrender to the all powerful and mighty :surrender:
Its the only way to learn and to build up knowledge that i can hopefully pass on to others in the future.
Sorry I've come across as "well and truly telling you".
I didn't mean my post to be that way and was, I thought, just sharing pertinent and relevant information to clear up a seeming misunderstanding about how the Tunze system you said worked in this fashion when it doesn't. There's sometimes a fine line between thinking outside the box and reinventing the wheel but also understand it's a whole lot of fun thinking things through and designing systems yourself.
I'm sure there's a way it can be done with float switches etc.
I look forward to seeing your design in due course!;)
John
Final points then I'll shut up.
One of the reasons that a consistent level of water in the sump is beneficial is so an auto top-up can be incorporated. If the water level is oscillating between two points as the return pump is switched off and on, a conventional auto top-up cannot be implemented. Depending on the size of your final chamber in the sump and the system's evaporation rates, topping up manually may be required twice a day. An auto top-up would be infinitely preferable!
Some pumps don't take kindly to being switched on and off too often, and will increase wear and tear and shorten its working life. If perchance it jams temporarily (not unknown by any means), then there can be a lot of heat generated which would be transferred to the sump water. Depending on what you have in your sump (e.g. if a DSB, Miracle Mud, other "live" filtration) it could be detrimental to your system.
You've said one of the reasons is because you're away a lot so want a system that's not going to flood and is easy to start off again. From experience and mouthfuls of detritus over the years, syphons are not always the easiest things to restart, particularly in a confined space such as under the tank. I'd rather have a system where the only thing you need to do is restart the sump return pump!
One of the good things about the dual standpipe method is that in the event of a partial blockage, the emergency overflow kicks in so that the cycle between sump and display is maintained at the "normal" rate - the water continues to be heated/skimmed/filtered. The removal of the blockage is not time-critical as the basic functions of the system are still being performed.
Lastly, sod's law usually dictates that any failure is going to happen while you're both away for a fortnight on your summer holiday and someone else is looking after the tank. There's always potential for something to go wrong even in the best designed system - the more complex the solution, the more scope there is for something to fail!
Hope this isn't interpreted as telling you again! I'm now outta here! ;)
John
Sorry I've come across as "well and truly telling you".
I didn't mean my post to be that way and was, I thought, just sharing pertinent and relevant information to clear up a seeming misunderstanding
John
I don't mind john :D I didn't take it as a telling off, just a general comment to all the replies ive had!
Lots of answers but no real explanations....:annoyed::whistling:
I do thank you for finally imparting some knowledge in my direction which i will use in any future designs or theory's my dreamworld mind puts my way! :worship:
I understand that the standpipe or overflow box is the best way to go...makes perfect sense and works almost flawlessly, but neither of those options were viable to me at the time hence why i was pushing the siphon idea around.....I read that putting a t-piece on the return pump line with a ball valve in the sump allows the pump to stay on constantly, as the ball valve spills water back into the sump if it drops too low, but then you'd still have an issue with the siphon not restarting should it stop so the idea has now been knocked on the head....for now!! :D
Still dunno how you calculate flow through a diameter x pipe driven by gravity though.....:confused:
Thanks for everyones comments, I'll be starting my sumpless/skimmerless thread soon!
:thanks:
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