Flow rate into bulk head ????

newfishliny

newfishliny

Member
now that my tank is up and running 90 gal glass
how do I get the bulk head strainer to be fully covered with water.
my pump is a mag 7 750 gph , is it that the pump is to small in ratio to the over flows of 1'' AND THE RETURNS OF 1/2 ".
OR IF I just add more water to the sump.
This is a little confuseing to me, if broomer is listening give me a shout . I need help from any fishy right now
thanks for the help
 
gregzbobo

gregzbobo

Member
this is an easy one. Turn your return pump off, and just pour freshly made saltwater into the tank and it will drain down into your sump to within maybe a couple inches of the top. This way when power fails, you have a bit of breathing room. Just rememebr to take some water out of the system when/if you add more rock or sand to be sure it won't overflow. And if the strainer is one that goes through the side of the tank, I don't think you CAN cover it completely, just because of the way it will drain. I may be wrong on that one though since my drain is in a weir type overflow box.
 
gregzbobo

gregzbobo

Member
Sorry, I just reread your post and you say you only have a 1/2" return? That DOES seem a tad small, and a mag 7 also seems a tad small for a 90 gallon as well. You need at least 10 times tank size turnover, if not 15-20 really. I have a 65 with a pump that pushes 1000 gallons per hour, and am at about 15 times turnover. If you want 15 times turnove, you'd need a pump pushing about 1400 gph and a larger return line for sure. And a larger drain would not hurt either.
 
broomer5

broomer5

Active Member
Don,
Let me refresh my head here - ya know - reboot the brain.
You have two (2) 1" back wall drilled overflow holes ~ each with bulkhead/strainers installed ~ both plumbed back to your sump ?
You have a Magdrive 7 running the return through 1/2 line(s) ?
Adding more water to sump will not raise the level in the tank, providing you have enough water in the sump right now to completely cover the intake of the Mag7.
It will only raise the level in the sump.
Granted - the fact that you would have more head pressure above the intake of the Mag in the sump would indeed add a tiny bit more flow up to the tank ....
The water level in the tank is dictated by the following;
1) where you drilled the holes
2) how the water falls/exits through the strainer/bulkheads
3) the rate at which the water is pumped into the tank
4) the square surface area of the 90 gallon tank
Period.
A single Mag7 pushing water up to your tank - a tank that has TWO 1" overflows - will run at a level to JUST WHERE THE WATER BEGINS TO TRICKLE out of the two overflow holes.
No higher - your pump can't pump enough water to do it.
The water falls out too fast - and you're stuck with that level.
Having these two 1" holes/overflows - man you could probably use a larger return pump. Two 1" overflows should be able to handle 1400 gph. You're only pushing 600-700 most likely.
The tank dimensions are probably 48x18x24.
That's 48" L x 18" W = 864 square inches of surface area.
Each inch of tank will be around 3.75 gallons
A Mag7 running full bore at say 700 gph = 11.75 GPM.
If you watched your tank fill with this pump - you'd noticed that the level in the tank would rise about 3 inches per minute.
That's not a lot of flow into a 90 gallon tank.
If you wanted - you could add another pump, say another Mag7 and another return line.
Run it with a ball valve for tweeking if necessary.
Run this secone pump on a timer if you wanted to for a pseudo wavemaker. Sort of stir things up a bit now and then, and add some randomness to the flow in tank flow patterns.
You certainly have the overflow capacity for more PUMP if you want to go that route.
Lastly: You really don't ever want the bulkhead strainers COMPLETELY submerged under water. Doing so means you've exceeded the flow that they can comfortably handle. If for some reason you're not there to witness it, and there is blockage of some form, then the tank level will rise up and possibly overun the tankwall rim.
If you increase your single pump, or go with a tandem pump set up ...... you'll gain a lot of turn over, intank circulation and may be able to reduce any powerheads you have in the tank.
May be able to - NOT will be able to - okay
If you choose to go this route - and you notice your water level is just halfway up the bulkhead strainers of your dual overflows - you got it made in the shade my friend !
Balanced - well running tank/sump/return rates and increased water turnover/circulation.
 
pmauro

pmauro

Member
Since you are the expert with this stuff maybe you can answer this question that just poped into my mind while reading this post.
I just ordered my new 300 gal+ reef ready tank it is supposed to have 2 1 inch overflows which will drain directly int a 119 gal sump. the pump I will be using will be a dolphin 3000 to circ through the sump and back into the tank. And 4 395 gph powerheads in the tank. Am I going to have to have Tencor add another overflow to handle this much pump? :rolleyes:
 
broomer5

broomer5

Active Member
Yes pmauro,
If you want to use that return pump - you'd better contact them and drill some more holes.
Dolphin 3000
3,400 gph @ 1 foot head pressure
3,000 gph @ 5 feet head pressure
You'd be wise to ask them for technical advise - since they are preparing the tank for you. I'm no expert although nice of you say - it ain't true.
The tank manufacturer is the expert IMO.
Tell them what flow/sump you're planning to use - and listen to their experienced advise.
I would imagine going to larger than 1", and having possibly 4 holes may be necessary.
Depending on the size, and if you're planning to use any of the holes for returns.
 
newfishliny

newfishliny

Member

Originally posted by broomer5
Don,
Let me refresh my head here - ya know - reboot the brain.
You have two (2) 1" back wall drilled overflow holes ~ each with bulkhead/strainers installed ~ both plumbed back to your sump ?
You have a Magdrive 7 running the return through 1/2 line(s) ?
Adding more water to sump will not raise the level in the tank, providing you have enough water in the sump right now to completely cover the intake of the Mag7.
It will only raise the level in the sump.
Granted - the fact that you would have more head pressure above the intake of the Mag in the sump would indeed add a tiny bit more flow up to the tank ....
The water level in the tank is dictated by the following;
BROOMER YOU EXPLAIN YOUR SELF SO WELL , YOUR POINT WAS WELL MADE" GOLD GUPPY AWARD " MY OVER FLOWS HAVE BALL VALES AND MY RETURNS HAVE BALL VALES, I think I'll go for a mag 9 .
one thing I just noticed I have those flex ball type spray tubes attached to my return bulk heads and when I turn off the pump it
siphon back to the tank, if the flex where any deeper in the tank it would over flow my sump , how to break the siphon .BIG ISSUE, BIG WET MESS** IT COULD HAPPEN**
OTHER WISE THANK YOU AS ALWAYS
Don LI/NY
1) where you drilled the holes
2) how the water falls/exits through the strainer/bulkheads
3) the rate at which the water is pumped into the tank
4) the square surface area of the 90 gallon tank
Period.
A single Mag7 pushing water up to your tank - a tank that has TWO 1" overflows - will run at a level to JUST WHERE THE WATER BEGINS TO TRICKLE out of the two overflow holes.
No higher - your pump can't pump enough water to do it.
The water falls out too fast - and you're stuck with that level.
Having these two 1" holes/overflows - man you could probably use a larger return pump. Two 1" overflows should be able to handle 1400 gph. You're only pushing 600-700 most likely.
The tank dimensions are probably 48x18x24.
That's 48" L x 18" W = 864 square inches of surface area.
Each inch of tank will be around 3.75 gallons
A Mag7 running full bore at say 700 gph = 11.75 GPM.
If you watched your tank fill with this pump - you'd noticed that the level in the tank would rise about 3 inches per minute.
That's not a lot of flow into a 90 gallon tank.
If you wanted - you could add another pump, say another Mag7 and another return line.
Run it with a ball valve for tweeking if necessary.
Run this secone pump on a timer if you wanted to for a pseudo wavemaker. Sort of stir things up a bit now and then, and add some randomness to the flow in tank flow patterns.
You certainly have the overflow capacity for more PUMP if you want to go that route.
Lastly: You really don't ever want the bulkhead strainers COMPLETELY submerged under water. Doing so means you've exceeded the flow that they can comfortably handle. If for some reason you're not there to witness it, and there is blockage of some form, then the tank level will rise up and possibly overun the tankwall rim.
If you increase your single pump, or go with a tandem pump set up ...... you'll gain a lot of turn over, intank circulation and may be able to reduce any powerheads you have in the tank.
May be able to - NOT will be able to - okay
If you choose to go this route - and you notice your water level is just halfway up the bulkhead strainers of your dual overflows - you got it made in the shade my friend !
Balanced - well running tank/sump/return rates and increased water turnover/circulation.
 
pmauro

pmauro

Member
Is a 3000 too much pump? I thought that you wanted a lot of flow in a large tank. Should I go to a smaller pump? or could I use a maniflod to bleed off some water flow to circ in the sump, run the fluidized filter, skimmer and that sort of stuff. Any Ideas? Gee this isn't going to be as easy as I thought.
 
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