Spec'ing Refugium to replace Canister Filter

[gregredic]

My goal in building a refugium (this will not be used as a sump) is to eliminate
the use of a canister filter from my DT. I currently have a 110 gallon saltwater
DT tank with crushed coral substrate, approximately 140-150 pounds of live rock,
a HOB protein skimmer, and canister filter (I have an inline UV light that I
will be putting in place on the return side of my refugium that I am about to
build). I am wanting to build a refugium in order to do away with the canister
filter (if anyone thinks I can't use the refugium in place of the canister
filer, please explain???). My cabinet doesn’t allow for much room below my tank
and I can't locate the refugium anywhere else in the house (small house). The
space I am working with is 36" wide, 14.5" deep, and 19" high. Would a 20 gallon
refugium be big enough for my tank, or would I need at least a 30 gallon
refugium? I was thinking about getting this 20 gallon tank from Petsmart... http://www.petsmart.com/product/inde...157&lmdn=Shape I
have no plans to move my protein skimmer down inside the refugium. I was
thinking I could simply get an old aquarium that will fit under the tank that
would have 3 chambers. The first chamber would be where the water comes in from
the overflow box, the second being the refugium, and the third would be my
return going to the DT. Can anyone recommend an good/affordable overflow box and
return pump that will work well together? Since it is only 13" high, what depeth
of sand bed should I be aiming for? I was thinking if I made the refugium
approximately 10" tall that I could have a sand bed in the 4-5" range. Is my
logic flawed there? Should I try to make the refugium deeper or shallower? since
I won't have my protein skimmer on the refugium, can I forgo putting in a bubble
trap on my refugium? I don't see where I would be getting any bubbles in the
system.

My single biggest question is what gph should I be looking for
if I am putting in a 4-5" sand bed, a little liverock rubble, and I want to grow
cheato??? I am thinking with about 12 gallons of the total 20 being the actual
refugium, would I need about 175 gph? Would I need to subtract out the 4-5" that
will be the sand bed and only count the water capacity??? Bare in mind that my
primary goal is to be able to remove the canister filter unless it is needed
from time to time in emergencies. Currently my bio load isn't that big, but over the next 6 months I am going to
be adding more load. Currently the DT is growing plenty of algae and
unfortunately I have been battling cyanobacteria for the last month or so (I am
slowly getting it under control). I believe putting in the refugium will aid in
the cyanobacteria (lower phosphates), provide good filteration, and be a
breeding ground for copepods. Does my diagram look correctly designed?

[Reefing Madness]

Looks sound. Your return pump is going to be based off of your intake, or overflow box gph, you are going to want to match as closely as possible to that.
And with that said, your going to want to T off the return line, run a line back to the sump with a ball valve inline, this way you can fine tune your return flow.
Melevsreef.com | Acrylic Sumps & Refugiums

[gregredic]

Reefing Madness, thank you for your reply. I was planning to do the T with the valve returning water back to the intake...just didn't put that in my drawing. I keep reading that I want slow waterflow through the refugium. Would I be looking for an overflow box in the 100 gph range and I can then just fine tune everything with the valve off the T? I assume with a 20 gallon refugium, I would be wanting to change the water over in the refugium around 2 to 3 times an hour?

[gregredic]

Do you think I would be good to use an Eshopps PF-800 Eshopps PF800 Overflow Box, 125 gal tank, Single - AquaCave and then getting a return pump with a similar equivalence?

[Reefing Madness]

At 3 times turn over rate in sump wouldn't you be looking at CPR CS90 SIPHON AQUARIUM OVERFLOW BOX by CPR Aquatic - AquaCave ? But, yes, what you have above is a good choice and will work, then just get a pump rated with headloss at 800gph.

[gregredic]

I ended up going with this overflow box Amazon.com: Eshopps PF-300 Overflow Box - Up to 75 gallons - 6 in. x 3 in. x 10 in.: Pet Supplies and this return pump Amazon.com: Viaaqua 1800 - 480 GPH Submersible Pump: Patio, Lawn & Garden that is a Viaaqua 1800 - 480gph....aiming for around 300gph after head loss. Hopefully all will work out well. I will be sure to post results of the refugium once I get it built...maybe it will be of use to someone else in the future.