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Drilling for Gold

The Gnome

Feb 5, 2006
I was wondering if anybody has any experience in drilling 125 g Oceanic tanks ?

I was planning on running a closed loop filtration system in a addition to my regular open loop. I'm going to drill several holes in the backside of the aquarium for intake and outake. I guess I'm mainly wondering if anyone who has/had an octopus has done this before and what strategy was used.

How many holes should I drill for adequate flow ?
Should I have multiple intake and one outake or vice versa ?
What diameter holes are suggested for the intake & outake ?
Should the holes be positioned in a certain way to maintain the glass's structural integrity ?

I am extremely nervous about drilling this tank, because I nearly broke my back moving it yesterday, not to mention the $$ spent on it would not be easily replaced.

This will be the first step of many with this project, so I want to do it right ! Any input is greatly appreciated !:biggrin2:
Don't worry too much about the drilling. It isn't difficult, and it has been done by the amateur untold hundreds or thousands of times. Given that, it is possible to do it wrong! Don't put holes too close to each other or the edges of the pane. I've heard one hole diameter as a good rule. Don't bother with a dremel unless you want to go hard-core and make slots for an external overflow. Go onto eBay and get a diamond holesaw from a guy named Lau** in Hong Kong. It'll cost you about ten bucks and be on your doorstep in a week. Use light to medium pressure on the drill and an intermediate drill speed. I've drilled 7 holes for one-inch bulkheads. I bought a portable drill guide from Sears. If you go to their website and do a search you'll see it. It helps a lot keeping the drill straight (remove the springs, though). Keep the hole saw wet during the operation. Some people make a dam with clay, others trickle water from a hose. Secure a scrap piece of glass on the back of the pane so the saw has something to go into without chipping the back of the hole.

I've never set up a closed loop, so I can't give you any other info regarding placement.

Good luck,

Thanks Dan !

You've inspired me to buy a $10 hole saw, *lots of people have told me this* instead of just going all out with a dremel. What's 10 bucks when compared to what I paid for the whole tank, right ?

I'll post pictures on this thread when I get the cutting done and the bulkheads installed. The positioning of the holes is key, from what I've learned, but I still don't know how many holes are necessary. I want to do the minimal amount of holes that I would need to achieve adequate flow throughout my tank.

I plan on running an Iwaki 40RLT for the closed loop system and a Blueline 40HD for my skimmer. They're both external pumps that are rated to pump around 780 gph so I think that 2 or 3 holes for the closed loop should be adequate.

What do you think ?
I really don't have any experience with closed loops. Most ceph keepers don't run the same massive amounts of flow that reefkeepers do. I don't have any extra flow besides what I get from my sump return spraybar. Just enough to prevent dead spots.

Is there a specific reason that ceph keepers don't have the same amount of flow as reefkeepers? Do the cephlopods react badly to it or do they just require less ? I'm still new to this site, and I aspire to keep a bimac in my 125 that I'm talking about drilling - so any info you have about cephlopod specific issues .. like this one .. I would love to hear it!

I had a thread about the ink that octopi expel and the conclusion/solution to that problem was to get a monster skimmer with a bosshog pump running it. The closed loop was an idea that was added to the 'schematic' later on, just to keep high level of oxygen in the water.

Is the closed loop a bad idea for cephs ?
I have been researching this for my tank I am setting up.

Some reports show that cephs (specifically octos) like high flow rates and high oxygen ratios that high flow rates can generate.

Below is the like to a good article on Octo raising. Lots on tanks specs and options.

Advanced Aquarist

Your specific tank setup will determine your needed flow rate and where to drill.

P.S. I read alot about your pump model-everyone says it is a good choice. You get the U.S. or Japan version? Both are good from what I hear.
Love this line! :
"powerheads essentially function as a tentacle blender for the curious animal."

A truer thought was never expressed! Yep, go with the double (or more) drilled system...it has worked out very well for me.
Thanks to everyone for the advice on this topic !

* P.S. I read alot about your pump model-everyone says it is a good choice. You get the U.S. or Japan version? Both are good from what I hear. *

I'm getting the Japanese Iwaki pump from a local reefkeeper whom I met online. I'm getting it for a steal ! I'm buying the blueline and the iwaki for $100!

Still planning the drilling procedure, and I'm trying to work up the nerve to 'operate'

I'll keep everyone posted !
The Gnome said:
Still planning the drilling procedure, and I'm trying to work up the nerve to 'operate'

Trust me, once you do it you'll feel stupid for not drilling earlier!

Just do a practice hole on a piece of scrap glass before you do the tank, and be sure it isn't tempered.

The bulkheads are ordered, so it's just a matter of time. My friend who is helping me drill is going to bring his digital camera so I can post pics of the bulkheads installed for posterity and future drilling projects.
If you want some more tips on drilling, check out Reef Central Online Community

Their on-page search function doesn't work very well, but you can go to Google, type in your search parameters (ie, "holesaw drilling glass") plus "site:reefcentral.com"

To be honest, ReefCentral is a much better resource for tank modifications, because there are relatively few of us here doing such radical things :smile:


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