Drilled aquarium hole placement

[Aloginname]

I've just got a second handAqua Oak 200 litre (Maidenhead Aquatics type). It's 100cm x 40cm x 50cm x 5'5mm from float glass.
I have lots of questions about drilling it. Ideally I want as little visible inside the tank as possible.
How many holes should I drill? I'm looking to plumb it into the house plumbing, so want one from the tap, one to the drain, and one to the external filter. Is 3 holes too many?
Where can I position the holes?
How wide should they be?

 

[fishguy1978]

I would use an Eclipse overflow or similar.

 

[duanes]

You really only need 1 hole, the efluent (outflow).
Influent pipes (from the tap) can simply be positioned over the rim.
As to where they are positioned, that can be personal preference.
Since I keep riverine species, I place the inflow on one end, to allow flow across the length of the tank, and the outflow (the only hole I drill) on the opposite end.
One of the other reasons for having inflow coming from over the rim, is I also like as much surface agitation as possible to influence adequate gas exchange, and oxygenation.

As you can see by the way the plants bend, flow cn be quite strong halfway across the length of the tank.

The tank in the foreground, is about the same size as yours (55 gal). Water enters above the rim, (right) and flows out on the left.
Drilling such a small tank, can sometimes seem a bit of overkill, but I am a bit paranoid of overflows, that require the use of siphon tubes.

 

[CHOMPERS]

I'm not a fan of the siphon tubes either. I use to sing praises about them, but sometimes they build up gas inside. And then they stop flowing. And then you get to clean up a mess at 3am. I am a glutton for punishment, so it took several flood clean ups before I started drilling tanks. It is a skill that you won't regret learning.

Keep your holes at least one diameter from the edge. Other than that you can put the holes anywhere you want. I have a preference for drilling the bottom and adding a stand pipe, but drilling the side or back gives you better security in the event of a leak.

 

[Aloginname]

I've been watching videos and seeing pictures about drilling tanks, and the holes are always large and use massive piping. Currently I use Eheim 12/16mm pipes in my undrilled tank, and would like to continue using them for the new drilled tank. I'll use a wider sieve on the inside outlet pipe to minimise risk of blockage. Therefore I'm looking for small holes to fit the Eheim tubing. Is there any advantage of using 1 inch holes?

 

[fishguy1978]

The flow rate increases by 50% from 3/4 to 1in is why. I have a rack of 8 29g aquariums where I should have used 1in drains but used 3/4. I need to increase flow but can’t without redrilling the tanks.