Flow

[Troy F]

Does anyone know how much flow a Oceanic overflow can handle? I'm trying to decide on a return pump and have a few options open to me.

[danny zubot]

If you know the size of it you could use the calculator on reef central to figure out the rate.

http://www.reefcentral.com/calc/drain.php

[jws444]

I think they can handle 600gph. I didn't buy the overflow version for my Oceanic, but I assumed it comes pre drilled? I'd measure the hole. If it's around 1.5 inches, then 600 gph would be about right I think.

[danny zubot]

A 1.5 inch hole can handle 1200 gph. After head and linear footage loss you should be able to run any 1200 gph pump quite safely.

[Aquattro]

Personally, I don't use my overflow for flow. I want a slower flow so my skimmer and carbon can filter the water. Currently I run about 500gph thru my sump.
For flow, I use in-tank streams.

[danny zubot]

I too have downgraded my sump flow to about 650-700 gph. I haven't really noticed the skimmer pulling any more skimate out of the water though. Did you?

[Aquattro]

I've always run that volume, so I can't tell.

[Delphinus]

I kind of look at it from the other way.. i.e. I wouldn't so much expect an increase in skimmate production by slowing the sump flow, but rather if the skimmate production amount DIDN'T decrease then it confirms to me that I didn't need to pump that extra energy into the higher flow in the first place.

[danny zubot]

Good point Tony, I never thought of that.

[Troy F]

The problem for me is with the confines of a smaller tank I don't want a bunch of powerheads in there. I'm also going without a traditional hood so I don't want a tonne of plumbing going everywhere.

I don't quite follow the reasoning of slowing the water down in the sump to filter it. Once it's in your skimmer, it's in your skimmer and the volume doesn't change. If more water is changing over wouldn't it still get filtered? Now if your using your carbon passively I guess slower flow in the area would help.

[StirCrazy]

I don't quite follow the reasoning of slowing the water down in the sump to filter it. Once it's in your skimmer, it's in your skimmer and the volume doesn't change. If more water is changing over wouldn't it still get filtered? Now if your using your carbon passively I guess slower flow in the area would help.

exactly what I was thinking.

How big is the overflow Troy?

Steve

[Troy F]

I don't know Steve but I'll bet it's drilled for 1" bulkheads. I'm hoping 1.5' out and 1" in.

[StirCrazy]

if it is a 1" hole then the max that would flow through it is 800 gph. I would look more about 500 gph to be safe.

Steve

[Aquattro]

Well, I figure since I run carbon passively, try to use my sump as a settling area, and really, there ain't a hope in hell of creating the flow I need from my return pump, going slow was better. Also, I read it on the Internet, so it must be true.
I remember running a MAG 12 as my return on my 75 wide open, returning to two nozzles. The flow was nothing at all. To rely only on one return pump to generate enough current, you'd need a 3 or 4 inch bulkhead, at least for my purposes.
Therefore, slow sump flow means greater contact time with filtration media, greater settling of detritus and less micro bubbles returning t the tank. Also much quieter going down the overflow.
As with everything, YMMV, and if running 3000gph through a sump works, you'll enjoy not having the tank cluttered with powerheads.
Of course 1 small stream in the back corner would be more than enough for a 58...... :biggrin:

[Troy F]

Makes sense with the carbon and settling of detritus.

If for some reason the tank has a 1" bulkhead I'll obviously have to scale back the return accordingly. I'm also planning a closed loop split with an ocean motion or SQWD.

Also, I read it on the Internet, so it must be true.

:smile:

[Delphinus]

I don't quite follow the reasoning of slowing the water down in the sump to filter it. Once it's in your skimmer, it's in your skimmer and the volume doesn't change. If more water is changing over wouldn't it still get filtered?

I just mean that there's probably a point of diminishing returns, where increasing the flow through the sump beyond that threshold, does not yield results proportional to the amount of extra energy you put in to create that extra flow. (Am I making any sense? It makes perfect sense in my head, but translating it into Eeeeenglesh words is maybe losing something). Plus, increasing the flow through the sump increases the likelihood of microbubbles. So there's a comfortable range. Under the lower limit of that range, would be ineffective (because you're just skimming your sump), and above the upper limit, would be inefficient (note not "ineffective" - "inefficient").

Now if you want your sump to be the main source of flow for the main tank, and eliminating microbubbles, one method you may want to look into is the method of submerging the downspout completely, and then tuning the overflow (with a valve) to match the sump return pump flow exactly. Then no air gets drawn into the downspout, and, no air bubbles. The only thing is you need to have a secondary overflow pipe to drain into the sump in the event the valve gets blocked or something. I forget what this method is called, but I think it does have a name. If I remembered it I'd tell you so that you could search on it. But there have been a few to employ this method and they seemed happy with it.

[Troy F]

I wouldn't want to push 3000gph through your average sump or anything but 1100gph doesn't seem unreasonalbe to me. Having said that; after talking to Marc, the Oceanic overflows will only handle 8 to 9 hundred gallons so adjustments to my plans will change.

[SuperFudge]

Hey Troy,

Yeah unfortunatly they dont handle much, but what ive done in the past is also use the bulkhead that was intended for the feed line as an additional drain.

Tie the two together into a manifold, and you can bring your feed line up the back and over the rim instead.

Its only another 3/4" Drain, but probably will handle an additional 5-6 hundred GPH.

Marc.

[Troy F]

Good point Marc. I may do that.