Return pump from sump on 75g AGA reef ready BB tank

[nobody]

I am not sure what size return pump i need for a 75g tank. This is my plan. the tank has two holes drilled in it on the bottom of the overflow. I am going to have the megaflow kit in the overflow. The return will come up and i can either split it to return to the tank with one on each side of the overflow. Or i can have one go up to the overflow and have a y back into the tank on the right side if you are looking at the tank. The overflow box is not in the middle it is more to the left. Either way besides the sump return i am going to have two koralia circulation pumps one on each side of the tank. these link show the two koralia pumps i am thinking about the koralia 3 will give me about 23 times circulation not including the sump return. the koralia 4 will give me 32 times. which one will be right if i am doing a BB. and what give mag drive should i get for the return from the sump

koralia 3
http://www.thatpetplace.com/pet/prod.../7/product.web
koralia 4
http://www.thatpetplace.com/pet/prod.../7/product.web

[Dagrape]

What skimmer are you planning on running. The best thing to do is try to mach you return pump to your skimmer output.

I am running a PM bullet1 skimmer driven with a Mag12 and have a mag 9.5 return. Honestly I think my return pump is pumping more than the skimmer. The slower the water flow through your sump the better skimming you will get. Try not to use a big return to help increase turn over.

As for the Koralia's, I would go bigger. The nice thing about BB is there is relly NO limit on flow. I have (2) ClS's and (3) modded Tunze 6025's in my 90gal and I want more flow still.

[nobody]

asm g2 it does 350gph so?http://www.thatpetplace.com/pet/prod.../7/product.web

[Dagrape]

Based on that I would go with somthing like a mag5 or a mag7 at MOST. Maybe put the return on a squid to get some alternating flow aswell.(wish I did) If you go much bigger the water will go through the sump faster than the skimmer can skim it.

[nobody]

what is a squid?

[nobody]

i was really planning ont he mag 12. with the head height it will drop closer to 700. That will give me around 10times an hour filtration. you sure i should drop all the way to a mag 7

[Dagrape]

There are really 2 ways of looking at it. And I am kinda on the fence about it myself. I have been thinking about increasing my return pump because of this.

1st way
If your skimmer can only proccess 350GPH, so you only want 350GPH moving through the sump. That would mean every drop going into the sump goes through the skimmer to the return and back to tank. If you run 700GPH through the sump only 1/2 of the water goes through the skimmer and the other half just bypasses and returns to the tank unfiltered.

Way #2
Since your skimmer will only skim 350GPH no matter what you do, you will only get 350 gal of skimmed water returning to your tank every hour. So if you have a return pump that pumps 350gph, 100% of the overflow water is filtered. HOWEVER if you have a return pump that pumps 700GPH, you may only be filtering 50% of the water that overflows....BUT it is still the EXACT same amount of filter water returning to the tank.

SO regardless of what you do, on a 75 gal tank with your skimmer you will only get 5x volume/hour filtration.

Hopefully someone else has another outlook on this, cause that is just how I think it works. Try doing a search on return flow, or matching return pumps and skimmer output. I knw there are alot of threads out there on the topic.

[Dagrape]

Originally Posted by ionracing

what is a squid?

A squid is a little device that has 1 water input and 2 ouputs. It alternates flow from one outlet to the other so you can have cheap alternating flow from 2 return nozzles all fed from 1 pump.

Look up SCWD squid in google and you will find it.

[Fly Guy]

Originally Posted by Dagrape

There are really 2 ways of looking at it. And I am kinda on the fence about it myself. I have been thinking about increasing my return pump because of this.

1st way
If your skimmer can only proccess 350GPH, so you only want 350GPH moving through the sump. That would mean every drop going into the sump goes through the skimmer to the return and back to tank. If you run 700GPH through the sump only 1/2 of the water goes through the skimmer and the other half just bypasses and returns to the tank unfiltered.

Way #2
Since your skimmer will only skim 350GPH no matter what you do, you will only get 350 gal of skimmed water returning to your tank every hour. So if you have a return pump that pumps 350gph, 100% of the overflow water is filtered. HOWEVER if you have a return pump that pumps 700GPH, you may only be filtering 50% of the water that overflows....BUT it is still the EXACT same amount of filter water returning to the tank.

SO regardless of what you do, on a 75 gal tank with your skimmer you will only get 5x volume/hour filtration.

Hopefully someone else has another outlook on this, cause that is just how I think it works. Try doing a search on return flow, or matching return pumps and skimmer output. I knw there are alot of threads out there on the topic.

Ill offer this. I USED to think the same thing as your second viewpoint. "Whats the difference?"...350 gph is 350 gph...all you people saying your return flow to skimmer processing capability actually makes a difference are smoking crack. THEN I pulled a little experiment for myslef to prove the people saying it made a difference wrong. Well.......long story short.......I proved them right. It surely wasnt a perfect lab experiment....but the result was clear enough in my mind that I trust my results.

[Dagrape]

So based on that I should get off the fence and just leave my mag9.5 as a return pump....and possibly use a valve th throttle it back.

Or maybe just buy a mag18 to run my skimmer, and leve the 9.5return wide open.

[Fly Guy]

Also consider that just becasue your sedra 3500 is rated for 350 gph...its pumping aior along with that water....you are more likely only really processing 200 gph or so