Flow question

I am in the design process of my tank and I have a question in regards to flow. The tank is a 90 Gallon MarineLand with 1 corner overflow, I have heard flow rates on these from 550 to 800 gph I am thinking the vertical drop that the overflow has will have some bearing on how much it will flow.

This will be a FOWLR set up

My plan is to use my Aquaricare algal scrubber set at 12 inches below the tank, it has two 1 1/4" inch inlets and outlets so its ability to flow is decent, I am just curious if the 12" drop from the tank is enough to generate decent flow out of the tank? From the Scrubber I would drop into the sump, of which I have not decided which way I am going for that. My stand is planed at 42" tall to provide enough depth for the scrubber and the sump, plus I do not like having to bend over to look at a tank so the extra foot in height will be beneficial in allot of ways.

Here is a quick and dirty Google Sketchup of what it would look like.

 

I have always been told the return should be 10 times the tank size. but I know that the scrubber needs a certain amount of flow in order to work properly also or it will be in effective. I am assuming you are using the return to feed your scrubber or are you going to use a separate motor?

 

vertical drop has nothing to do with flow rates. If you are using a standard durso pipe, it is nothing more than a stand pipe overflow.... water overflows into the pipe. It is not a drain coming off the bottom where head pressure would dictate flow rate.

Your overflow is going to overflow what ever your return pump supplies to the tank.

How much flow do you need for your scrubber?

Are you going to use a skimmer?

 

Flow rates for our sytems really do not apply. I can guess where they came from. I'm sure they are some hold over from W/D filters, or hOB/canister filters.... but for reef tanks with sumps it has no bearing. The only flow rate you need is dependent on the equipment you want to supply.

 

For a 90g tank I'd suggest a pump that is putting 300-500gph back into the DT. Any more than that is just waste. Let your powerheads take care of circulation.

 

I knew that but the flow coming out of the scrubber will determine his return pump so the sump doesn't run dry right? I meant it could mean the difference of a 400 gph to 750gph pump. Just guessing?

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Thanks to all of you!

I was planning on letting the overflow of the tank supply the Scrubber, then the out put of the scrubber go to the sump. Right now I have a Mag 1200 for a return pump. At 5.5 feet of head I believe it should return between 550 and 600 GPH, however I have read that they produce allot of heat. So maybe I will need to look around.

I do plan on running a skimmer in the sump. I wish I knew the flow rate of the scrubber, it has two 6" wide trays and is about 40" long so if I can get the flows split properly between the two sides it would only be flowing half of the total flow. With the Mag 12 about 225 gallons per side.

I understand about, whatever you pump to the tank the overflow will return but I do think if you were using a pump capable of say 1200 GPH that you would be able to overwhelm the single return? Am I wrong on this thinking?

Thanks again for the replies,
Scott

 

A mag 12 @ 5.5 ft is not gonna lose that many gph. It might go from 1200 to approx 750 but not that low.

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ReefBruh, you are correct according to Mag Drives numbers. I thought I saw a chart somewhere that showed them considerably lower than this chart, but ofcourse this chart is from the manufacturer!

Danner Supreme Mag-Drive Aquarium Water Pump/Powerhead

Thanks,
Scott

 

Check the specs. From what I read at 6 ft the rating is 950 gph so you might want to get a smaller pump or get a check valve on it.

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