Help with refuge setup

cboyfan2020

cboyfan2020

Active Member
I am setting up a refuge for my 120g tank. It will be a 40g breeder and I have some questions. I have a mag 7 for the return with a tee off the return line to feed the fuge. On the tee'd line I will put a ball valve to control the flow to the fuge. I want to put a spray bar type attachment to the end of the return line to help eliminate need for extra powerheads. Here are my questions.
1) If I switch to a mag 9.5 how much flow in gph will I have at 5' head.
2) will having the ballvalve on the fuge line cause too much back pressure on the 9.5 or will it just shoot more water straight to the tank?
3)I want to put the spay bar with the holes pointing behind the rock work. How many and how big will the holes need to be? I would run 3/4" PVC of the mag 9.5, should I reduce it to 1/2" when I get to the spraybar to help increase the velocity of the water?
Here is a sketch of my current plan. Any help would be appreciated.
 
broomer5

broomer5

Active Member
I'll try my best to answer your Q's.
1) If I switch to a mag 9.5 how much flow in gph will I have at 5' head.
AGREE: I'd estimate about 750 gph @ 5'head.
2) will having the ballvalve on the fuge line cause too much back pressure on the 9.5 or will it just shoot more water straight to the tank?
NOPE: Having the ball valve on the branching tee will not necessarily create backpressure.
If the valve is shut - you would have a slight pressure drop due to the tee in the return line.
When you crack open the fuge feeding valve - you'd expect more pressure drop to the display returnline = less flow and speed up to the main tank.
3)I want to put the spay bar with the holes pointing behind the rock work. How many and how big will the holes need to be? I would run 3/4" PVC of the mag 9.5, should I reduce it to 1/2" when I get to the spraybar to help increase the velocity of the water?
YES: Here's what can happen.
If you drill too many holes, or too large of holes - then you lose speed/velocity of the water shooting out into the display tank.
One hole - shoots out fast.
Two holes - shoots out less, and so on.
The total "GPH" does not change - but the speed at which the water enters the tank will drop considerably.
A length of PVC pipe with multiple large holes will not give you the result that I think you are after.
If you choose wisely - and stratigically place a limited number of smaller holes in the PVC pipe - I believe you'll get the water movement that you desire.
Too many big holes - and the water will just sort of slowly flow out. Not much speed - not much in the way of blowing detritus around.
 
cboyfan2020

cboyfan2020

Active Member
would this work with a 10" spraybar,
2 holes to the sides, 2 holes down and 3 holes out to the front. Or is that too many and can you please give a suggestion. Also would it be better to go with a mag 12 or something?
 
broomer5

broomer5

Active Member
Interesting design ;)
What kind of overflow are you using on the 120 ?
Drilled tank ?
External overflow ?
How much water gph can the overflow handle ?
 
broomer5

broomer5

Active Member
Okay - we can play around with some numbers and see what happens.
Let's say you use 3/4" ID PVC pipe for your returnline & spraybar.
The ID of the pipe = .75"
Diameter = .75"
Radius = .375"
Pi = 3.14
3.14 x ( .375 x .375 ) = .44 square inches.
The opening of a piece of 3/4" PVC pipe is roughly .44 sq."
So if you run the return to the tank WITHOUT a spraybar - you have the Mag9.5 delivering around 750 gph into the tank - through this .44 square inch opening.
If you use a spraybar - the quesiton comes up - "how many holes should I drill .... and how big should they each be ??"
You want enough holes of the right size to get all the flow through that you can - without choking it off and creating excessive backpressure - right.
So .. how many and how big should these holes be ??
One way to look at this is to pick one proposed drilled hole size, and figure out what IT'S area is.
Do it the same as we did for the 3/4" pipe.
Say we use a 1/8" drill bit.
Diameter = .125"
Radius = .0625"
Pi = 3.14
3.14 x ( .0625 x .0625 ) = .0122 square inches of area.
So this little 1/8" drilled hole has .0122 square inches of area.
The open 3/4" pipe has .44sq" right.
Divide .44 by .0122 = 36
So you could have thirty-six 1/8" holes drilled in the spraybar - and that would basically give you the same square area as the open 3/4" pipe without a spraybar.
1/8" holes are pretty small, and may clog up on ya.
So doing the same thing with 1/4" holes ( skipping the math for now )
You would need 9 holes ( each one having .049sq" area ) to equal the opening of the 3/4" pipe without a spraybar.
Nine 1/4" holes would equal the same as the 3/4" pipe opening - so in theory - you would not choke off the flow, create excessive backpressure or harm the pump.
Smaller holes - faster water speed - but if you don't have enough - lots of backpressure on the pump.
Larger holes - slower water speed - less chance for backpressure.
Personally - all of this sounds good on paper, but I don't really know for sure how practical it all is when selecting a pump and making your spraybar.
Knowing that you have the dual 1" drain/overflow - that can handle 1400 gph, I would think that running a Mag12 @ 5' head would deliver around 1000 gph.
But I would not use 3/4" PVC with that pump.
I would use 1" for sure.
1" PVC has .785 square inches of area.
If we went with 1/4" drill bit ...
.785 divided by .049 = 16 holes required.
That may be more than you want to drill - unless you run the spraybar the entire length of the tank.
So 3/8" holes might be another option.
That would give you
.785 divided by .115 = 7 holes
You can play around with the math - or just set it up like you plan to - drill some holes - check out the flow - and drill some more if required.
I think this is close to being right.
How long is your tank ?
And what length do you want the spraybar to be ??
 
cboyfan2020

cboyfan2020

Active Member
I posted this on another board and have been speaking with a guy by the name of melev.
Here is what we came up with.
Pump: Mag 12 which will give me 1120gph at 5'
return pipe: 1.5"
refugium pipe teed of main pipe:1/2"
Spraybar pipe: 3/4" OR 1" pipe will be 12" long
holes: 1/4" holes x 8-9 holes
How does this sound?
thanks for all your help:D
 
broomer5

broomer5

Active Member
Sounds good.
I forgot you were teeing off to feed your fuge ( that's what I get for not going back and reading the entire thread :( )
You may find you need a few more holes - or you could increase the ones you drilled by upsizing the drill bit. Or not.
I think it's worth a try - and make modifications as you go if needed. You should have some good velocity using the Mag12 and 8 or 9 1/4" holes. You can always drill more or make'm a tad larger.
Good luck with it - and sorry for my long windy reply above :rolleyes:
Love to see a pic when it's done - and let us know how it works out - ok
 
cboyfan2020

cboyfan2020

Active Member
That long windy reply is how I learn what I need to know. Thank you for your halp and I will definately gets some pics up for you. Gotta wait on my stand and canopy to get finished though. It has been a mont but I cant complain because it is being built out of oak and its FREE!!;)
 
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