# Refugium? sump?



## sparkiesford

I have done a lot of reading in the last 3-4 months on saltwater and a few questions I still have are what is a refugium used for? I always see a smaller tank or two under the cabinet to support the main tank. I understand its for filtration but how does this work? Also is it gravity fed then a sump caries it back to the tank? What if the power goes off? Also does the extra water volume count toward stocking parameters, more simply put, a 55g tank with two 10g refugiums
, would that be the same as a 75g when it comes to stocking? Also I here a lot about natural filtration, if you have enough LR and LS does that mean you don't need a HOB, other filtration devices? And one last question, what is a good book for saltwater, I got a few from barnes and noble but they aren't very helpful. 
I am sorry for all the questions, I tried to make them mostly intelligent questions. 
Kirk


----------



## harif87

Okay.

A sump, by defenition, is just a vat of water that sits externally from the tank (usually underneath). The extra water volume definately gives you more elbow room when it comes to stocking, but its not as easy as "55 + 10 +10 = 75" because the fish do need room to swim. Its helpful when keeping messier fish, like groupers. 

In a sump people tend to have refugiums (AKA Fuge). Fuges serve for filtration purposes, which are all by biological means. What usually goes into a fuge is some macroalgae, which serves to reduce nitrates and nutrients in the water column. This helps prevent microalgae growth (i.e. the algaes we dont like). Often found in fuges are pod populations (tiny crustaceans) which can thrive untouched inside your fuge. The reason one would want pods in their system is because it serves as live food for your fish, and there are some fish who wont eat anything but live pods (e.x. mandarins). If you didnt have a fuge that allows the pods to establish a popluation out of reach of hungry fish, then the pod populations would be decimated by the fish being that the pods wouldnt be able to reproduce fast enough to keep up.

Generally sumps are gravity fed, via an overflow box, or if the tank is drilled, through bulkheads on the bottom of the tank. The water goes down to the sump from the overflow and then is pumped back from the sump to the tank via a return pump.

Here is a pic that you can follow the water travel (the red arrows are direction of water travel):


----------



## TheOldSalt

A sump being used as merely a volume vat can be used to give more stocking room, but most sumps are not used for this, but instead used as refugia, which do NOT give you more room for fish, as the refugia animals themselves are using up that capacity.
Well, technically they can help a little, but it's not a good idea. There is a lot more than mere gallonage involved, and a 55 with two 10-gallon sumps on it is not anything close to a 75 in actual practice.

These things must be set up properly, or, as you have guessed, you will have a big problem when the power goes out and restarts. Correctly set up, the entire flow stops when the power stops, and the flow restarts when the power is restored. Only ONE pump is used for the sump subsystem!! Using two will lead to disaster every time, as it is impossible to keep the flow rates of two pumps perfectly matched all the time.

The more filtration you have, in general, the better. Yes, you can get by with only a lot of LR & LS, but why tax them to their very limit all the time when you can use other filters as well? Besides, you'll need lots of water circulation anyway, so you might as well put your water pumps to filtering work while they're at it.

"The Conscientious Marine Aquarist" by Robert Fenner,
"Invertebrates" by Robert Fenner and Anthony Calfo,
and
"The New Marine Aquarium" by Mike Paletta are three of your best choices for books. Any of them will be a big help, but all 3 of them will be a huge help.


----------



## sparkiesford

Thanks for the write up. I appreciate the input. I am just trying to learn as much as I can now , before I jump in. It may be a year or better before I can afford the commitment. But at that time
I want to at least be as knowledgeable as possible. 
Kirk


----------



## Fishnewb1

how do you sync the 2 fuge 
tanks? an overflow box?


----------



## harif87

an overflow box would work, but one would have to be higher than the other. It would be easier to just build the fuge in the sump.


----------



## Fishnewb1

I dont understand... I have a fuge and i wanted to put a coral propogating tank next to it below my 55. I wanted to know how to hook those up...


----------



## harif87

have the tank overflow into the fuge, then put an overflow box on the fuge to overflow into the sump, then the sump has the return pump


----------

