How big should my surge device be for a 180G reef?
- Thread starter esmithiii
- Start date
As big as you can bloody well make it! Seriously I would just push your overflows to the max and see what they can handle. Without knowing your setup it would be hard to imagine how much that would be. I think a 40 gallon would probably do the trick, with a couple 2" outlets. Are you going carlson or borneman style?
Tell us some more about your tank, specifially tank size and how its plumbed (including pipe sizes).
If you only have a 20 gallon sump your going to have a hard time with a large surge. Figure you sump has around 10 gallons of water in it. If you surged in 5 more gallons, your gonna be 3/4 full. That extra 5 gallons will have a negative impact on your skimmer if its an insump model.
If you only have a 20 gallon sump your going to have a hard time with a large surge. Figure you sump has around 10 gallons of water in it. If you surged in 5 more gallons, your gonna be 3/4 full. That extra 5 gallons will have a negative impact on your skimmer if its an insump model.
I noticed that the sump water level doesn't fluctuate nearly as much as you would expect it to. It does rise and fall with the surge, but the main tank does as well. My 2-2.5 gallon surges only made my 10 gallon sump fluctuate an inch or so, but they also made the main tank fluctuate this much.
Ernie, sump size becoming a problem is dependent on your overflow to sump capacity. If, without the surge device, your tank to sump to tank to sump loop is being run based on the limitations of the overflow pipe diameter/flow capacity (terminal velocity/flow), then the filling of the sump is limited by the rate of the overflow. Therefore, in general, the surge device will not significantly fill the sump anymore than it already is, it will however, fill the overflow box. Water level in the sump/overflow to the sump will be increased slightly or significantly by the increased head pressure of the water standing on the return pipe if the overflow pipes are not being run to their maximum flow capacity. The increase in flow will be dependant on how close to the terminal flow-to-sump capacity you already run the overflows prior to the surge device installation.
Rate of surge will be dictated by two main principles: Gravity and constriction. You can have the surge device as high in the air as possible. It will flow/siphon faster the higher you go, to a point: the maximum flow capacity for the diameter/length of pipe you use as the siphon tube. Ideally, the largest pipe reasonable for your reservoir should be used. This is limited severly by practicality. Using a three inch pipe as the siphon requires a large amount of head pressure/volume over the top of the siphon bend to prime the siphon. The more overhead pressure you have, the more volume the surge is going to be, again, causing overflow and sump limitations to figure in.
I'm not familiar with the overflow volume in the tank you have, however, for practicality's sake, the surge device volume should be limited by the volume of the freeboard left in the overflows (ie, volume of overflow minus the water volume normally present) + the volume of any remaining freeboard in the tank itself (unless you're running monster overflows and a big sump) + the volume that will flow to the sump during the duration of the surge device's delivery of the surge (compensated for the varying rates: ie, for every second, the surge device delivers x amount of water, and the overflows deliver y amount of water to the sump (this last figure to add is only effective if your overflows are not being run at full capacity). This one can be hard to figure and you start to get into conjecture, so be conservative. If you feel so intrepid, you can do frictionless calculations of gravitational acceleration of the mass of water; mass of water will be determined by volume of pipe (diameter and length). This should give you a nice conservative number, because, even so, for an accurate figure you have to add to this time from backpressure from the submerged outflow, friction from the pipe (unless you can find the friction coefficient of the pipe), etc.
On another note, don't short change yourself on the surge periodicity, make sure the overflow can totally recover. Also, don't forget, whatever you are returning to the sump via the surge, the sump was already taking a deficit from whatever was pumped to the device, so make sure the sump has the volume in it to fill the device without running the system pumps dry or cavitating.
Rate of surge will be dictated by two main principles: Gravity and constriction. You can have the surge device as high in the air as possible. It will flow/siphon faster the higher you go, to a point: the maximum flow capacity for the diameter/length of pipe you use as the siphon tube. Ideally, the largest pipe reasonable for your reservoir should be used. This is limited severly by practicality. Using a three inch pipe as the siphon requires a large amount of head pressure/volume over the top of the siphon bend to prime the siphon. The more overhead pressure you have, the more volume the surge is going to be, again, causing overflow and sump limitations to figure in.
I'm not familiar with the overflow volume in the tank you have, however, for practicality's sake, the surge device volume should be limited by the volume of the freeboard left in the overflows (ie, volume of overflow minus the water volume normally present) + the volume of any remaining freeboard in the tank itself (unless you're running monster overflows and a big sump) + the volume that will flow to the sump during the duration of the surge device's delivery of the surge (compensated for the varying rates: ie, for every second, the surge device delivers x amount of water, and the overflows deliver y amount of water to the sump (this last figure to add is only effective if your overflows are not being run at full capacity). This one can be hard to figure and you start to get into conjecture, so be conservative. If you feel so intrepid, you can do frictionless calculations of gravitational acceleration of the mass of water; mass of water will be determined by volume of pipe (diameter and length). This should give you a nice conservative number, because, even so, for an accurate figure you have to add to this time from backpressure from the submerged outflow, friction from the pipe (unless you can find the friction coefficient of the pipe), etc.
On another note, don't short change yourself on the surge periodicity, make sure the overflow can totally recover. Also, don't forget, whatever you are returning to the sump via the surge, the sump was already taking a deficit from whatever was pumped to the device, so make sure the sump has the volume in it to fill the device without running the system pumps dry or cavitating.
It's ultimately going to depend on your overflows and how much volume they can handle. Myself, I'm going to be taking a 10 gal tank and dividing it in half and running two toilet flapper surge devides from it so I can get alternating surges. My overflows will be two 1.5" ID standpipes: one Stockman and one Durso. This will be on a custom 80 gal tank (4'x2'x16") with a 65-75 gal sump. I've also thought about RCSD or maybe a pulsed ReefTec/Tunze or even an ATS unit. I keep changing my mind. 
Shane
Shane
It is a 180g reef ready with dual overflows using the stockman mod of the Durso standpipe. I have a 50g sump divided into three equal chambers. When I drain the last chamber (where the return pump intake is) the other two are about 3/4" full. I use 1"pvc pipe from the overflow bulkheads to the sump, each has one single 90 elbow.
I use a SEN900 return pump. I think the overflows can handle at least twice what I am putting through them. At one time I used a MAK4 pump and a RIO 900gph as return pumps and the overflows had plenty of velocity left.
I have a MyReef skimmer in the sump also.
Ernie
I use a SEN900 return pump. I think the overflows can handle at least twice what I am putting through them. At one time I used a MAK4 pump and a RIO 900gph as return pumps and the overflows had plenty of velocity left.
I have a MyReef skimmer in the sump also.
Ernie
Hi ,
have you ordered the tank yet.. I am getting ready to draw up some plans for my 300+ gal. I am gonna put a back-up overflow in the box. Probably 1.75". Maybe rig a second downtube to help with the surge if you are worried that the overflow couldnt handle it.
just a thought... if you havent got the tank yet.
have you ordered the tank yet.. I am getting ready to draw up some plans for my 300+ gal. I am gonna put a back-up overflow in the box. Probably 1.75". Maybe rig a second downtube to help with the surge if you are worried that the overflow couldnt handle it.
just a thought... if you havent got the tank yet.
Howdy all:
Just back from vacation so late post here.
Ernie your surge device plan sounds a little big to me without knowing some key details about your tank. For comparison, below describes my borneman style surge device. I have a 140 gal main tank.
A 5 gal bucket serves as my sump. Water is pumped into it with a mag 2
inline (giggle) where the maximum flow rate will never exceed the standpipe/overflow capacity of the bucket. About 4 gallons surge into the tank and across the 6' tank length. The surge lasts about 4 seconds as the sump empties. Period between surges is about 70 seconds. The return diameter is 2" Change in water level in tank is about 1/4" which is no biggy. All this provides a lovely surge, without knocking over corals and whatnot. The first second or so of surge contains bubbles, just like you would see when a wave breaks over a reef crest (looking up). For me, this is beneficial, at least visually. The bubbles dissipate in about 10 seconds. I have a dumb theory that these bubbles may act as some sort of pre-skimmer.
A very important factor with these things is the amount of change in the water level in the tank. Too little and your surge device is too small. Too big means a potentially nasty surge of water into the main sump that could affect r/o float valves or any wildlife in it etc.
So, for me, a 4-5 gallon surge in a 140 tank is about right. Yes I probably could have gone a little larger. The effect of one of these is awesome when I watch the softies swaying happily back and forth. I built mine for under 40 bucks (not including pump) and it is the best 40 bucks I have ever spent on my tank. Thanks Eric.
Just back from vacation so late post here.
Ernie your surge device plan sounds a little big to me without knowing some key details about your tank. For comparison, below describes my borneman style surge device. I have a 140 gal main tank.
A 5 gal bucket serves as my sump. Water is pumped into it with a mag 2
inline (giggle) where the maximum flow rate will never exceed the standpipe/overflow capacity of the bucket. About 4 gallons surge into the tank and across the 6' tank length. The surge lasts about 4 seconds as the sump empties. Period between surges is about 70 seconds. The return diameter is 2" Change in water level in tank is about 1/4" which is no biggy. All this provides a lovely surge, without knocking over corals and whatnot. The first second or so of surge contains bubbles, just like you would see when a wave breaks over a reef crest (looking up). For me, this is beneficial, at least visually. The bubbles dissipate in about 10 seconds. I have a dumb theory that these bubbles may act as some sort of pre-skimmer.
A very important factor with these things is the amount of change in the water level in the tank. Too little and your surge device is too small. Too big means a potentially nasty surge of water into the main sump that could affect r/o float valves or any wildlife in it etc.
So, for me, a 4-5 gallon surge in a 140 tank is about right. Yes I probably could have gone a little larger. The effect of one of these is awesome when I watch the softies swaying happily back and forth. I built mine for under 40 bucks (not including pump) and it is the best 40 bucks I have ever spent on my tank. Thanks Eric.
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