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ebojo
04/17/2011, 03:50 PM
I was looking to convert my 20L into a sump for my 75g. After looking around, the common build seems to be divided into 3 sections.

1 - overflow, skimmer, heaters..etc
2 - fuge
3 - return pump

The first and second stage are divided using an over-under-over setup, with 2 and 3 divided by a single piece of acrylic that the water flows over.

Has anyone done this setup, or something similar, and could offer dimensions of each section, and the height of each divider.

Also, I am not quite sure how to control the flow from the overflow into the first stage. The setup that I bought included an aquapro sump (bioballs...yuck), which used one of a spiral drain hose. Would I be better off replacing it with pvc instead? Should I have a small section in the first section for the water to flow into?

UnusualSuspect
04/17/2011, 05:55 PM
I built my sump with the return in the middle and the refugium isolated at the opposite end from the drain. The refugium is fed from a tee in the return line, so I can set the flow rate through the fuge (with a ball valve) independently of flow through the sump.

drain/skimmer --> bubble trap --> return <-- refugium

Just a design consideration, not really important here.

Dimensions - you need to design around your equipment, mainly the skimmer. Make your skimmer/drain section "just big enough" to hold the required equipment. You want as big a return section as you can get - a small return section will have you topping up all the time. Balance this with the need for a large refugium. Pick your poison...

(I designed my "over-under-over" (bubble trap) so the 1st compartment is 1" wide and the 2nd compartment is 2" wide. I keep my heater in the 2nd bubble trap compartment.)

Height of the baffles - your skimmer may dictate the minimum baffle height. If you decide to go higher, you can build a platform from egg-crate for the skimmer to sit on.

I pick a baffle height that seems like it would be good, then sit down and draw it out on paper. When you have it drawn up, figure out the volume of each chamber (multiply L x W x H), and the (normally un-used) volume from the top of your baffles to just under the top lip of the sump. There's a unit converter on the Reef Central home page, use it to convert from cubic inches to gallons.

Adding up the total volume of the skimmer/fuge/bubble trap/return chambers will give you your working volume - the more the better.

That "un-used" volume above the baffles becomes important in a power outage or other failure of the return pump. Your return line will siphon tank water back into the sump, and you need the sump to be able to handle this back-flow. The more, the better.

So - it's a balancing act - you want as much working volume as possible while still maintaining the ability to contain all of the back-flow and not flood the room during a power outage.

A lot of people, me included, use the flex drain hose. You can use PVC if you want. It's personal preference, really.

Controlling the flow from the overflow to the first stage is pretty much done with your return pump. Think of it this way - the overflow will remove exactly as much water from the tank as the return pump is adding.

"Small section ... for the water to flow into" - yes, I'd certainly consider a bubble tower to contain micro bubbles. Most sump builds I've seen incorporate a square chamber in the skimmer section with teeth cut in the bottom. I made one from 3" PVC pipe, two inches taller than my baffles, with teeth cut into the bottom. It works very well, especially in conjunction with a filter sock.

HTH.

Edit: here's a plan I drew up today, based on a 30 gallon, for when I convert my 90 from freshwater to reef. It has a working volume of 22.4 gallons (adds about 20% to the total water volume) and has a backflow capacity of 7.5 gallons. Baffles are 12" tall.

http://www.pbase.com/mlandry/image/134002755.jpg

ebojo
04/17/2011, 07:13 PM
i havent even read thru this yet, but u r the man for drawing a pic. i appreciate that

UnusualSuspect
04/17/2011, 08:11 PM
LOL - that drawing won't work for a 20L, it's based on a 30L. I just put it up as an example of something I'm working on.