75 gallon octopus tank (images)

[DHyslop]

In the downtime between ceph inhabitants, I renovated the plumbing on my 75 gallon tank. I have a similar thread on TONMO. I'll probably also double-post it on the DIY forum.

I basically cleaned up the plumbing a bit to make things quieter and have less water in the drain system to end up in the sump when the power's off.



Here's what it looks like with the room lights off. Its an Oceanic 75 with a DIY external overflow on an AGA pine stand. To the right is a trickle filter made from a 5-gallon bucket, elevated to the correct height by a $4 laundry hamper. In the scientific literature some (but clearly not all) bimacs have grown well over two pounds. Its often quoted that a ceph generates about three times the nitrogenous waste as a fish, so you can see why I wanted a massive biofilter.



The return spray bar is 1" PVC and comes through a threaded bulkhead in the back of the tank. Two 45 degree elbows bring the outlets up to the water level to minimize backflow when the power's out. Using a bulkhead for the return means I don't need anything passing through the lid, clearly advantageous for an octopus tank.



Here's a closeup of the spray bar. Fiberglass window screen and cable ties will keep a curious octopus out of the holes.



Here's the external overflow and biofilter. The overflow is just four panes of 1/4" glass cut to size by a glass shop. I cut twenty four 3/4 x 1/4" slots in the top of the tank's side pane (shown below) for the actual overflowing using a Dremel and a diamond bit. Behind the biofilter you can see the Aqualifter pump I use for my automatic topoff system.



Here's a closeup of the slots from outside the tank as water cascades over them. This overflow has been setup for about a year. The cable ties keep the octo-proofing in place (see below).



More fiberglass window screen keeps an octo out of the overflow. To keep the little guy from peeling it back and climbing under, my LFS gave me some nice rigid plastic stuff to sandwich the screen in.



Here's a short (1 mb) video of the overflow doing its thing.

[DHyslop]

Here's what my plumbing would look like if it were straightened. Most of the complexity is for redundancy and noise abatement. The highest ball valve increases the water level in the overflow to control noise. Total discharge through that line stays constant as you close the valve until the water level reaches the Durso. I try to keep the water around that level. The Durso goes directly into the sump and can handle all the flow if the main line is plugged.

The second ball valve controls the water level in the trickle filter. When that line is wide open I have a repeating flushing sound. When the line is completely closed the water level is a little higher in the filter than I'd like. I've been keeping it maybe 3/4 of the way closed. I should really replace these with gate valves, but I'm too cheap.

The third ball valve controls the flow going into the skimmer, which is a recirculating Aquamedic Turboflotor 1000 with an Ocean Runner 2700 needlewheel pump. I know its not the best skimmer in the world but it does its job and--since the neck is completely in the cup--its very easy to keep clean and producing at its best!



Here's my plumbing going into the stand.



Same shot from the inside. Before I drilled the holes in the stand I shored it up with a 1x4 and two 1x2s. The airline hose is the output for the ATO.



Here's the sump. Refugium and return section on the left. Reverse photo period keeps the pH stable overnight.



The money shot.



The pump is a Mag-7. I replaced the stainless (ha!) screws after they started to rust about six months ago. Net flow is roughly 375 gph. I've found the best way to grow chaeto is to stretch it out on egg crate--when you have it all in one clump the stuff in the middle dies. Behind the algae and invisible to us are the two float switches in series that--along with a 9V relay--power the ATO.



This blue bin is where I keep my feeder crabs. Its on a sliding shelf to make life easier. A simple siphon from the overflow through airline hose keeps the water fresh. A 3/4" bulkhead and strainer send water straight to the filter. The system is rigged like a HOB overflow to hold siphon when the power goes out, but even if it fails there's no flood and the crabs don't mind.



Closeup of the bin. Six gallons or so, got it at Home Despot. You can see the back half is sandy because the fiddlers like to bury themselves right at the water level. Since the picture was taken I've added crabs and some PVC fittings for them to play on. They like to eat lettuce and are quite the escape artists.

Many ceph keepers have their crabs in stand-alone bins and just change the water out every other day. Having mine plumbed into the system makes maintenance nice and easy!

Now that that's over with here's a few videos (2-3 mb each) of Ivar, the tank's new inhabitant. Tank-raised Octopus bimaculoides, arrived Friday 12/01. He's about four months old and has a mantle length of an inch or so.





My apologies for the video quality, new camera and I'm still learning. The first one is him soon after he came out of the bag, looking for a nice den. Second is him pouncing on a crab, slightly outside of frame.

Like most new octos, he's still pretty shy and I doubt we'll see much of him for the next few weeks until he's convinced I don't intend to eat him.

Dan

[Msby12]

beautiful *sniff* simply beautiful!

that tank is amazing!

[OoNickoC]

Very interesting! I like the crab storage. All in the dorm huh? I got harrased for a 6 gal!!!!lol.

[OoNickoC]

Very interesting! I like the crab storage. Is this at your work...? Or in a dorm. I got harassed by the FM for a 6g!!!!

[DHyslop]

Its in an apartment. Hopefully a house within a years time!

[thatguy]

That is sweet. I can't wait to set one up for myself.

[DHyslop]

This'll get you moving:

[AVALover5498]

Very cool!



-Chris-

[PLNelson]

Way cool movies.