water level in sump

[Reefer769]

im kind of confused about how you maintain a water level in your sump...

if i glue peices of acrylic 8" off the ground of a 12" tank, will the water level stay at 8" or will it go over?

[Reefer769]

i want to start cutting the acrylic, and i dont know how far from the top i should glue it, because i want to have it so there room for another 2 or 3 gallons in the sump, so there wouldnt be a flood. would i control this water level with the pump, and maybe a ball valve? and does it matter how high the walls are in the sump?

[SteveP]

i want to start cutting the acrylic, and i dont know how far from the top i should glue it, because i want to have it so there room for another 2 or 3 gallons in the sump, so there wouldnt be a flood. would i control this water level with the pump, and maybe a ball valve? and does it matter how high the walls are in the sump?

Essentially, the waterlevel in the sump is controlled by two things - The speed of the incoming water, and the speed of the outgoing water. If the two are equal, the water level will remain constant. Most setups acheive this by having an overflow that can out-perform the return pump, hence putting the emphasis on the return pump pushing water up to the tank, which then controls the speed the water overflows back down to the sump, the more water pumped into the main tank, the higher the water level in the tank, the further above the overflow level the water is, and the faster the overflow will run (in general).

The actual physical water level is set by the volume of water in the complete system - it must be enough to cover the return pump when the system is running, but still be low enough to handle the volume when the return pump stops and the overflow "overflows" until the Tank water level is below the level of the overflow box itself.

As for the Acrylic - if you look at my example (http://www.sjpdesigns.com/newreef/sumphowto.html) you'll see where I have two uprights that control the water level for the refugium portion of the sump. In this case, because the sump is sealed at the bottom, and the acrylic is sealed up to about 8" up, the water MUST fill the sump to the 8" level before it can flow over the barriers to the return pump.

If you want to go into more detail, feel free to PM me.

Steve

[Reefer769]

i just sent you a PM, but if you look at this first heres my ques.

once the water get up to that 8" barrier and flows over to the pump, will it ever get as high as 10" or 11" above the 8" barrier?

[zhenya]

i just sent you a PM, but if you look at this first heres my ques.

once the water get up to that 8" barrier and flows over to the pump, will it ever get as high as 10" or 11" above the 8" barrier?

Only when you turn off your return pump, it might get a bit higher if water will still syphon via overflow.You have to make sure that you have enough room left for that additional drainage, so not to have a flood on a floor ;)

[Poseidon]

Also make sure you put ball or gate valves on the inlet and outlet PVC pipes. That way you can fine tune the water level. It is very simple to do, just hard to explain. Once you get it set up and flowing you will see what needs to be adjusted.

[Reefer769]

i bought a ball valve from home depot for less than 2$, will this work? i am thinking about putting the ball valve in the middle of the return pump, sounds good?

[cubalz]

That will work. Basicially you want to be able to control the flow going out of the return pump to get the sump level right. When you get the ball valve installed turn on the pump and keep a eye on the water level in the main tank, if it looks like it is going to overflow, close the valve a little. After tinkering with it it will be set to the point that the overflow and return pump gph will match- then you can adjust the water in the sump to whatever level you want. keep topping off the water due to evaporation to that level you want and all will be fine!

John

i bought a ball valve from home depot for less than 2$, will this work? i am thinking about putting the ball valve in the middle of the return pump, sounds good?

[SteveP]

That will work. Basicially you want to be able to control the flow going out of the return pump to get the sump level right. When you get the ball valve installed turn on the pump and keep a eye on the water level in the main tank, if it looks like it is going to overflow, close the valve a little. After tinkering with it it will be set to the point that the overflow and return pump gph will match- then you can adjust the water in the sump to whatever level you want. keep topping off the water due to evaporation to that level you want and all will be fine!

John

If your overflow is bigger than your return pump speed, you shouldn't need ball valves, as the water overflowing would equal that being pumped up from the return pump. The most water that can end up in the sump is set by the level of the overflow grate in the main tank.

If your return pump is faster than the overflow can handle, then you can slowly empty the sump into the main tank, and overflow - so you'd restrict the return pump to match the overflow.

I have a 700gph overflow with a Rio 2100 return pump pushing a 5' head. No return pump restriction is required becase the Rio cannot push water into the tank faster than it can overflow back down to the sump.

Steve

[Reefer769]

would a cpr CS50 which drains 300gph, and a mag 5 that pushes 500 gph 4' up, be a good match?

[SteveP]

would a cpr CS50 which drains 300gph, and a mag 5 that pushes 500 gph 4' up, be a good match?

First, I'd check the specs on the Mag 5, I think at a 4' head it only pushes about 310gph. Assuming 500gph is right, if you think about it, you have already answered your question.

Supply to main tank = 500 GPH (the Mag 5)
Drain from main tank = 300 GPH (the CS50)

The water being pumped into the Main tank will overflow just as quickly as it can, but that would be limited by the overflow's capacity of 300 GPH. The MAG5 would be happily pushing 500 GPH into the tank from the sump, so the sump level would slowly drop (at about 200 GPH, or 3 Gallons per minute) until the sump was empty. This of course assumes the two figures are accurate, and they rarely are. I would suspect you'd either need to restrict the output of the Mag 5 - especially given that at a 4' head its spec is 310gph not 500, use a smaller pump (say 250 GPH at that head level - a Mag 3 perhaps) or increase the overflow capacity to accomodate say 400 GPH just to be sure. Of course, as the overflow gets dirty, the pump wears and so on and so forth, all those flow rates will change slightly.

Steve

[Reefer769]

ok well if the cpr overflow drains 300gph and the pump pumps 310 gallons then all i would need to do it hook a ball valve up to the pump and regulate it so it matches the overflow.

[SteveP]

ok well if the cpr overflow drains 300gph and the pump pumps 310 gallons then all i would need to do it hook a ball valve up to the pump and regulate it so it matches the overflow.

Remember, the limiting factor is the overflow, not the return. As long as the overflow can process more water than the return, you are good to go - the ball valve will give you control of that return rate to ensure this is the case

You can experiment with it a little too. If you open the valve right open, the sump volume will slowly drop and the tank level increase (assuming the pump is faster than the overflow). If you close the valve too much, the sump would initially fill, tank water levels would stabilize at slightly above the overflow grate, and the overall flowrate will drop. The ultimate test is turning off the return pump, flow rate drops to nothing, tank level drops to the top of the overflow grate, sump fills to it's maximum point. This is good test too, make sure that when the return pump is turned off, the siphon and overflows stop dumping water to the sump before the sump is full up ;)

The reverse test is to stop the overflow (cover the grate, block the pipe, whatever), and make sure the pump runs dry (or is turned off by a float switch) before the main tank overflows.

Steve