yalls opions on overflows.....

[Jrmass]

By overflows I don't think he's talking about turning a standard tank into a reef tank.. I've been refering to an internal overflow (RR) tank. And I'm pretty sure that's what DJ has been refering too as well (thus the need for a "restart pump" would not be needed here).

Also, when I was refering to a coast-to-coast overflow I was talking about a fully external one (one that would run the entire length of the backwall of the tank) thus saving all the room normally taken by an internal overflow as well as taking away anything that doesn't need to be in the tank.

[OneDummHikk]

I have been referring to internal drilled overflow boxes as well. I don't care for the external overflows unless its an acrylic tank. Then, you can cut the notches in the back of the tank and have it run into the external overflow box. If its glass, the only thing you can do is have the back glass cut shorter and let it run over the glass without notches in the glass. A lot of people swear by toothless overflows but it only takes getting the tank 1/4" out of level to see why toothless coast-to-coast overflows aren't a good idea.

[The Forbiden Reef]

I agree with (firsthestation). I use a mag 12 in my 90gal RR tank and I also run 6 korilia's in my tank. I tried the mag 9.5 and it didn't put out the water flow I wanted. Plus like he said with the tank being 4ft off the ground you will lose more flow than you think. Also you could add the ball valve like he suggested, but I run mine wide open. My fish and corals love the tidal wave I've got going on. My tank is in my living room and you can't even hear the mag 12 run, but I would perfer the corner over flow though because it seems easier to clean and watch for any jumpers. Good luck on making your decision.

[mgloop9656]

well since im bored and came across this i figured id put my 2 cents worth in. for starters why would you want to have dual overflows in a 90g tank?you want a small turnover rate in your sump from what i have gathered 3-5 times. so your talking 270-450gph. from my understanding your only going to get so much flow from one overflow no matter how big of a pump you have. your really not going to get much more than 600gph from one overflow due to the size of the pipe, water can only go through the hole so fast. so unless you have a really large tank where you would need to achieve a higher flow to the sump to get you 3-5 times you dont really need dual overflows.

[mgloop9656]

oh. btw i have a 90g and a mag 9.5 for my sump and a ball valve to throttle back the return. to achieve the flow in the tank that i want i have a closed loop with another mag 9.5. the return bulkheads for the loop have adjustable nozzles very much like a whirlpool tub to aim the flow

[The Forbiden Reef]

I don't mean to differ but from what I've read you want aleast 8-10 times the turnover rate also depending on the bioload. If you've seen some of my pictures every thing is doing great and is not bothered by the amount of flow I have. Yeah your right, with an external overflow you need the proper flow to keep up with the over flow box. Which depends on the rating of the box. But with an internal megaflow chamber in a RR tank its rated to the pump you use. I have seen a 3600 mag hooked up to 75 gal RR tank. Overkill and Loud but worked fine. Check out post 22 on this thread.

[Jrmass]

I have a hard time believing that a Mag 36 would work on a single overflow (seeing they can't handle more than 1500 gph/overflow *that's just what each piece of PVC can take*) . AKA the pump would have to be MORE than cut into HALF for that to work on a single overflow. On a dual overflow it would be possible as you would have head loss to take into concideration plus the fact that you would be diverting the water into two directions thus losing some more TWV (total water volume) in that connection.

The reason that I'm saying all of this is because I've tried to run my 3600 gph Dolphin External pump (which is 3300 gph at 15' of head) and if I go wide open on my dual overflows (using 1.5" pvc after the 1" bulkhead) and if I go wide open my tank will keep up... BUT, JUST BARELY!!! (and that's on dual overflows)

I have also heard that optimal water turnover rate is 8-10x but, it's not to the sump as you had heard. That is total tank turnover (aka using powerheads and whatever else you may have to move water in the tank) I'm not sure what the sump turnover is. I'm sure that all depends on what your sump can actually handle. Mine if I wanted too and with the design that I have can easily handle 15-20x turnover to the sump and I wouldn't even be kicking microbubbles back to the display. It's just another personal preference about how much total flow you want. I'm kind of the person who believes if you can do it... why not do it?

Jason

[OLDETOWNENORTHPETS]

Well, I put a Mag 3600 on a single 75 gallon MegaFlow. Worked. Period.

[mgloop9656]

Originally Posted by Jrmass

I have also heard that optimal water turnover rate is 8-10x but, it's not to the sump as you had heard. That is total tank turnover (aka using powerheads and whatever else you may have to move water in the tank) I'm not sure what the sump turnover is. I'm sure that all depends on what your sump can actually handle.

to my understanding you should have your sump turnover to be matched approximately to your skimmer so that your skimmer can run properly.like you said the high turnover rate should be achieved by other means other than your sump. yes i have also read that 8-10x is a good rate, but your sump should only be 3-5 times and then the other 5 or so by a power head or loop

[condiman]

Originally Posted by OLDETOWNENORTHPETS

Well, I put a Mag 3600 on a single 75 gallon MegaFlow. Worked. Period.

Ok I am just wondering how a megaflo that can handle 600 gph can keep up with a pump that is rated at 3200 gph at 4ft. How is that possible?

[mgloop9656]

Originally Posted by condiman

Ok I am just wondering how a megaflo that can handle 600 gph can keep up with a pump that is rated at 3200 gph at 4ft. How is that possible?

i was wondering the same thing. its only gonna drain so fast. most people use 1" bulkheads and i dont care if you put a 3" pipe on it, water will only go through that fitting so fast. i would think that the water would reach dangerously close to the top with one overflow and a 3600gph pump

[OLDETOWNENORTHPETS]

Well, took a 3600mag pump. Put a 2ft 1 inch hose to the intake off the megaflow. Used the #4 All-Glass sump hose back to sump. No restricters anywhere. Turned pump on. Pump ran. Water went into megaflow. Water then went to sump. Pump in sump then sent water back into tank. Ran it for 2 hours. Tried 2 pumps to make sure. That is how it worked. I think thats how most sumps work. AS I explained before, I wanted to know if it could handle it as 2 of my dual 75 gallon systems use 3600s and if I needed to shut off one side did I need to change the pump to do so.

[OLDETOWNENORTHPETS]

Would I leave it on all the time. No, could it handle it for a short time, Yes. I dont think it could do 1 gph more as you wouldnt believe the noise but, in an emergency, I needed to know if I had to change the pump.

[hansmatt]

maybe the piping from the pump restricted flow up, to match the max flow down...the determining restrictor was the pipe diameter?

[OLDETOWNENORTHPETS]

Thanks Matt, not sure how much the hose restricted it. Matches the diameter of the outflow on the pump and was only 2ft long.1 inch inner diameter I am pretty sure. I will have to check that out.