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Drilled or overflow box?


Pygmy Octopus
Nov 16, 2006
What is more recommended? A drilled tank or an overflow [sypon] box?

I'd prefer an overflow, because I have one laying around, that I'd cover with eggcrate and some sort of finer mesh [bridal veil?]. But if it is more highly recommended to have the tank drilled, I'll get it drilled.
I highly recommend drilling. It is neither difficult nor expensive to do yourself and adds a whole new level of reliability. Either way covering it is the tricky part, and if you end up drilling you should think about that aspect when you're planning the overflow.

What do you need to do it yourself? I was going to have them cut 3 holes at the LFS. 1 In, 2 out.

I'd use a bulkhead for the intake with either an external box [siliconed to the back, durso style drain to reduce noise] or just the bulkhead strainer with an external durso, without the box.

Like this:
Sounds like a fine plan.

The only thing you need to do it yourself is a power drill and a diamond-studded holesaw. The latter you can get off of eBay for about $10 shipped (some LFS will charge you $20 per hole!). Make sure you get the right size, IIRC a 1" bulkhead needs a 1 3/4" or a 45mm hole. The important thing is to keep water flowing around the bit as you drill.

If you search a site like Reefcentral you'll find a thousand threads with tips.

I actually used to work at this LFS, so I was going to have a coworker do it for me. I think I'll go that route and save myself the buying of a drill I'd use once, maybe twice.

Now I just need to find some sargassum [kelp like macroalgae] to make the tank look like a kelp forest, and I'm good to go :smile:
I use Durso intakes on my tank. I don't know if the intakes that you have drawn will work. Mine seemed to need to have the intake lower than the 90 degree bend to the sump, otherwise the air will just come from the tank side strainer and not be adjustable from the pipe top. You could put a 12.5 or 33 degree bend just before the tank wall and I think it should work, but you wont have surface skimming.

I also made a adjustable hole by drilling at the side of the pipe, through the cap and pipe. That way I can turn the cap slightly to make the hole larger or smaller.

I also used the "dual standpipe in single overflow" approach. It was no problem when I used clear flexible tubing down to the sump. Then I could tell if one was "flushing" when adjusting the hole for rate of flow.
I just checked ebay and the 45mm drill bits [45mm for a 1" bulkhead] are like 23 bucks before shipping, it would be cheaper for me to have it drilled. Weird.
Ok. Tank Drilled [my boss did it for free, so what the heck]

Now, should I just put an elbow on it with a strainer [elbow to keep the water level higher] or build an overflow box out of acryllic around it?
A strainer/elbow will do fine. If you were keeping anything except an octo I'd recommend a box for more efficient surface skimming--but it is much harder to make escape-proof.

Besides, you can also add a box at a later date if you want to use the tank for something else.

If its a smaller octo its probably a good idea. You've got a few options for mesh: I bought a roll of fiberglass window screen from Home Depot for a few dollars, and I've heard Nancy mention the plastic netting that produce sometimes comes in.

im actually gonna eventually convert my octo tank to both from a box. on my reef tank i took peice of plastic rain gutter and cut it in half long ways. then i siliconed it to the top back of the tank and drilled a hole out the back. by doing this ive got surface skimming to the max with the extended overflow system and a good size hole to move the water fast. also the space it creates is being used as a refugium with a crushed coral sandbed and rubble in it. works great houses millions of copopods and helps filter out the water.