planning a refugium

[jc]

I have a 600gph cpr type overflow box that I want to drain to a 20g high tank. In the tank I want to put 5" of sand and some cheato. I also want to try to hang my bak pak skimmer on the refug. The pump I plan on using would be a mag 9. The length from the floor of my stand to the top of the tank is 4' 4" and the distance from where the pump would be to the back of the tank is 1'. Would the mag 9 work? or should i go with the 7. I plan on following the example of www.melevsreef.com sump model A. Which is about the size of my 20H except for the height. I am going to use the flexible pvc from the overflow to the refug and use a ball valve on the output of the pump to regulate the flow followed by flex pvc up to the tank. What do you guys think? Also do I just use pvc elbows to hang the flex pvc to the edge of the tank or is there something better like some type of directional piece I can add. My goal with the refugium is to lower nitrates, hide my heater and to move my noisy skimmer to the stand. Will my plan work?

[GaryP]

I think you may end up with to much flow going through your refugium. It sounds like you are trying to make it do double duty as a sump and a refugium. I'm not sure how practical that is going to be.

[jc]

Point well taken. I can keep the heater in the tank and try to hang the protein skimmer on the side of refug where the water comes in. If it doesn't work then I can always put it back on the side of the tank. Is there a way to slow the output of the overflow? maybe with a ball valve? If I can slow the overflow down then I can get a smaller pump. This is what I am going for.
http://www.melevsreef.com/29g/sump/sump3.jpg

[hobogato]

if you get a smaller pump, the overflow will slow as a result. it will only go as fast as the return pump.

[jc]

How does that work? I though the overflow works independently from the pump. If the overflow has a 1" bulkhead doesn't that mean it will output the same amount until it runs dry? Does that work on drilled tanks, maybe?

[GaryP]

You may be better off having a combo sump fuge like that in the pic you posted built from acrylic.

[jc]

I do plan on adding the baffles into the 20H. The dimensions are almost the same. My main concern is with the flow rate on my cpr overflow. It says 600gph and I know that is to fast for such a small refug. I was hoping I could put a valve on the output of the overflow to slow the rate down. Then I would get a pump that is slightly overpowered and put a valve on the output.

[brewercm]

How does that work? I though the overflow works independently from the pump. If the overflow has a 1" bulkhead doesn't that mean it will output the same amount until it runs dry?

I always find this tought to explain. The easiest is to set your overflow where you want it in the tank then fill the tank until it starts to run over the overflows(if you have a hang on type you will have to start the siphon once the tank is full). Once you have your sump area where the return pump is at the level you want(MAX Level acceptable without overflowing the sump) with no more water coming from the tank you are set. Now you can turn on your pump and the overflow will only work at the rate of your pump.

This is why I prefer more than one overflow outlet from the tank if possible that is rated higher than the return pump. If one was to clog up the other will still do the job, otherwise you could end up with overflowed tank.

[jc]

Its like a fog starting to lift. My brain I mean.

[brewercm]

I'm here to confuse. ;)

[jc]

I get it now. The output of my external overflow is not 600gph but "up to" 600gph. The flow of which is contingent upon the output of the pump into the tank.

[hobogato]

dingdingdingdingdingdingdingdingdingding(pointing to nose) we have a winner! :P :lol :w00t

[Magneto]

A hopefully simple way to explain the over flow only goes as fast as the pump.
Think of your tank as full of water right to the point where it is about to go over the over flow.
Your flow rate is 0 thru the over flow.
Now add 1 cup of water to the main tank.
You should have 1 cup of water that will go down the over flow.
If you add 1 cup every min, you will have 1 cup/min flow rate going thru the overflow.
Up that to two cups every min and your flow rate would be 2 cup/min
So the over flow only has to handle water that is added to the main tank beyond the point where the tank is full.
So at this point the person with the cup controls how much is going into the tank and out of the tank.
The next step is replace the poor guy with the cups with a return pump and there ya go.

All of this will stay true till the point where you have exceeded how fast your over flow can drain. And if you do that you have what we call a mopping experience.

[jc]

Thanks for the help guys. I decided to go with a mag 5 for a nice smooth flow through the refuge. I got everything I needed at Alamo Aquatics and they were very helpful. Now how deep does the water have to be to grow cheato. I want to have a DSB of about 5". That would leave me with about 6" of water above the sand. The available space is 16 x 12. Not counting the area for the pump to sit in.