Water flow... stumped.

[JohnNLuc]

I don't know where to begin. Maybe there is an easy solve for this, maybe not. I have a frag tank under my main that is plumbed to the main with pvc. gravity pulls the water down from a homemade utube (2 90 degree elbows) made of pvc and the return is put back into the tank using a pump and the same pvc utube design. (Hope your all still following) On both sets of pipes I have ball valves to control the water flow and get a constant where the water being pulled down is equal to the water being pushed back up. The question is when i start it no matter how hard i try to equalize both I can never get an equal of give and take (I have sat a couple of hours fooling with both ball valves to get the water to not move) Is there an easy way to get this to equal out or am I doomed to spend the remainder of my days fooling with these damn valves?

 

[juskeepswiming]

first of all you should never use a valve for the water leaving your main :? your drains should be able to drain the water that gets pumped in the main...the more water that gets pumped...the more water drains(to a certain point). if too much water is getting pumped into the tank, eithere your drain isnt large enough or your pump is too big, just control the valve on the pump return

 

[JohnNLuc]

So what you are saying is that I should open the ball valve on the drain line all the way? wouldn't this cause the frag tank to overflow due to the pump not being able to carry the water back in fast enough? The pipes are 3/4 inches wide tia

 

[ellisz]

As long as the drain can handle the pump you are fine. If it can't, get a smaller pump or use a valve to slow the pump water down. The drain will flow as fast as the water it gets, to its limit. Your pump always needs to be rated at a lower gph than the drain/overflow.

 

[JohnNLuc]

I am not quite following you. If i leave the drain all the way open, won't the frag tank overflow?

 

[juskeepswiming]

the only thing that can be a problem is if your pump pumps too much into the main, and you can fix it by slowing it down. open the drain all the way, if the water level in the main keeps rising, close the pump valve a little until the water levels off.

 

[juskeepswiming]

and what kind of frag tank do you have underneath? I mean the tank and lighting.

 

[juskeepswiming]

the frag tank will not overflow because the only water going into it is the same volume of water that is being pumped out

 

[JohnNLuc]

Okay, but lets say my pump is weaker? do I leave the return all the way open and than cut the drain down with the valve? I mean i've had both a half way and fooled with both and cannot for the life of me get this to level off. do I A. leave the drain all the way open and fool with the return line valve? or B. keep the return valve all the way open and fool with the drain line? sorry if im repeating myself over and over but like i said i cant for the life of me get the water to level off.

 

[JohnNLuc]

The frag tank is a small 10G with a little over 5 watts per gallon of PC lighting which im using to keep some softies.

 

[juskeepswiming]

if your pump is too weak and only pumps a little bit of water, only a little bit of water will drain. OPEN THE DRAIN ALL THE WAY! look at it this way...if you throw ten quarters into the air, only ten can come down (unless im around, then you wont have any money left). simple law of physics

 

[ellisz]

Leave both wide open if possible. if the tank water gets too high, crank the pump valve back. You can put a 500 gph pump on a 1000 gph drain. The drain will only do 500 gph since that is all that it is getting. If the frag tank is underneath, it will work just like a sump setup. Do you have a sump as well or are they combined?

 

[pufferman]

how can that be if the frag tank can overflow with too much water draining, and not enough water being pumped back. Eventually the frag tank will overflow. It would be better to get 1500 gph pump on a 1000 gph drain, and then control the pump output with a ball valve. Always get a larger pump output than drain input. It is easier to control the flow from a stronger pump than have a little pump and trying to control the drain.

 

[juskeepswiming]

It is easier to control the flow from a stronger pump than have a little pump and trying to control the drain.

huh? :?

 

[ellisz]

Always get a larger pump output than drain input. It is easier to control the flow from a stronger pump than have a little pump and trying to control the drain.

Uhh, no. The drain will only see the water that the pump provides. Turn the pump off and the overflow stops draining. Turn it back on and as the pump fills the tank, the water spills over the drain pipe and goes to the sump/frag tank. The drain will only drain what the pump provides.

I ran a mag7 on a megaflo overflow for 2 years. The gph of the pump was around 500+ and the overflow was rated at 600 gph. The pump was wide open and the drain was wide open. Never flooded. If I was to push 700 gph through a drain rated at 600, the tank would overflow. The sump does not overflow unless you get a back siphon when the pump is turned off.

 

[kukki]

well if im following this right, and im prolly not lol...

did anyone suggest putting a T ball valve on the return, and just letting some drain back into the sump, so you can leave the overflow drain all the way open, control the flow of the return pump but not add all the back pressure or whatever its called?

the overflow can only put as much water back into the sump as the pump provides it, if its to much for the overflow then id just use a T

i just got my overflow and i keep the ball valve on it part the way closed , only because my pump is putting 300 gph back in to the tank and the overflow is 600..... it was making alot of bubbles in the sump and annoying me because the overflow was always empty, so i used the valve to keep the water in the overflow just JUUUUST above the top of the bulkhead, i dunno how i got lucky it was a pain lol

 

[MarineFlake]

To the original question...No, a ball vavle on the overflow will not bring balance to the farce Luke. It complicates it. Take the ball vavle or any valve out on your overflow. I have a dual overflow, can push over 1000GPH. I have a Mag12 underneath with a ball valve on the return pump (Plumbed in line so I can 'throttle back' the return water. O ya, your question...No you will not flood your sump *unless* you add too much water to it and you have not drilled holes in your return lines to compensate for power loss resulting in back siphoning. A hole on each return pipe just below the water line will do the trick.
The physics...You have a 10G, start by placing 7G of water in it (Salt water please, k, thx...) Throttle back your return pumps ball valve to almost nothing. Alas, slowly but surely you will hear the water start dribbling over the overflow box and water should siphon (If primed already) into the sending box and down the sending tube(s). Once this happens, leave it. When you are convinced that the water level in your tank wont budge (It wont) and your sump will not over flow (It wont, youll actually 'lose' about 1/2G or so to fill the lines and tank) Once your are comfortable, start to ease up the ball valve and you will begin to hear the gurgling, etc of more water. Thus, your sump level gets lower still and the main tank gets a little higher causing the overflow to take in more water. Once you get a level in the main tank you like, great, sit back and enjoy, though with a 10G sump, at this point you will probably have to add another couple G of water to make up for whats in the lines and in the main tank. (Salt water please, k, thx) Once you add enough water to the sump to cover the pump enough, your done.
Pointers..Gurgling/slurping..Lots of ways to approach this. Personally, I simply jack up the water flow (return ball valve) until it gets quiet. Monitor the tank to make sure Im not going to flood the main and Im done. I dont screw with it again.
evap..Your water level in your sump will drop as water evaps. Top off with RO/DI water (Hold the salt please!) to raise the level where it was. This maint your sg / salinity. (Roughly)
Drill those holes! to prevent back siphoning. This is how you get a free trip to the carpet store. If you do not take steps to prevent back siphoning, you will lose power, back siphon about 15G into the sump and like magic, you have now have a custom salt water carpet.
Water changes. Dont mess with the ball valve..Simply cut power to your return pump and let it back siphon until it stops (Becuse you drilled those holes, right?...You did drill those holes didnt you??) Pump out the nasty water, pump in the equal amount of salt water adjusted to your tanks SG.
Additives..Dump em right in the sump! Though as you are using it as a frag tank, you may consider dosing it..
Thats it, my brain dump as short as I could make it. trust the farce Luke, it wont over flow your sump if you follow the bouncing ball..

 

[JohnNLuc]

I understand this now but my problem is I also have a real HOB overflow for my sump. If i throttle the return line down from the frag tank I will end up just empting my sump first. Wouldnt this effect the pvc u tube i made causing the frag tank to overflow until the sump was empty?

 

[JohnNLuc]

You know I also think this has to do with how the utube is set up. I made a quick paint drawing of it

 

[pufferman]

oh i see, i was thinking about something else. totally lost track of the kind of system we were talking about.