Disadvantages in low flow reefs...

[Reefguide]

I have been forced to split my main return in two using those snap on segments... Problem was that I have a finger leather that not been opening completely because he's being blasted by the return. So I split the current around him... but it have cut down the current quite a bit. I could probably move the leather but he has attached to the back glass and dont want to scrape him off, plus he looks perfect there... I know certain corals require more current than others but besides that are there any big disadvantages to reducing my flow?

Thanks

 

[Bluetangclan]

Just add a powerhead or two not aimed directly at the coral. Should be good. You need good flow to avoid dead spots where crud can accumulate. A reef tank should turn over about 10 times per hour. I have 2 Penguin 1140s and whatever my Rio on the return is churning water in my 55, thats at least 650+gph

 

[O P Ing]

hi.
I am confused. Splitting the return into two separate lines does not reduce the flow rate. half plus half is still a whole, right? :?

 

[LFS42]

OP,
This is a case where 1/2+1/2= something less than whole
Every time you divert flow from the straight, it reduces flow.
I'm not sure about the formula, but it happens.

Reef,
My finger leather is very moody. Everytime I change anything, it takes a few days for it to come back.(and talk to me again :wink: )

 

[stlfishguy]

I used a splitter because the current from my return pump stirred up my DSB no matter how I angled it. I found out later that the sugar sized sand starts to hold together better after a while. It drastically reduced the current in my tank but I just added another powerhead to intersect the stream of one of my outputs.

 

[O P Ing]

Every time you divert flow from the straight, it reduces flow.

hi.
The reduced flow is due to appearant "head" pressure, but this is a very minor issue since Reefguide is spliting using two outlets of the same size. It sounds to me he is using the LocLine type split.

The flow rate should be about the same, but since the cross section is doubled, the velocity is decreased to half.

I am not disagreeing with you, LFS. I just saying that it is not the case in this situation.

 

[npaden]

O P ing has it right.

"Flow" and "Velocity" are two entirely different words but are often confused by alot of people.

If you are using a 1.5" pipe you can have double the flow of a 1" pipe at relatively the same velocity. If you held your hand in front of the 1" pipe you would feel the water exiting the pipe at relatively the same velocity as the 1.5" pipe but you would have double the flow.

Same would hold true in your circumstance. Rarely are the velocities at the output high enough to significantly reduce flow by splitting it. All you have done is drop the velocity in half and flow should stay relatively the same.

Check out this months article on pumps and plumbing for some even more confusing stuff.

FWIW, Nathan