Overflow Help

[Reeferbro]

Hi
I have got a second hand 55 gallon aquarium ( aquaone 980) with a 20 gallon sump. The old overflow was a DIY HOB but it doesn't work very well so I want to drill the tank and make a proper overflow. I will be using a dolphin p-2500 return pump ( 1500lph) so what size hole, overflow box and bulkhead/PVC piping will i need? Also If any one knows about an aquarium shop or someone who could do it for me cheaply in sydney or on the central coast? Sorry for asking so many questions.
Cheers

 

[Reeferbro]

Oh and it will be a Calfo overflow

 

[DrRob]

How many holes are you going for? The more the bigger the overflow, but the more redundancy and the more options to silence it, however the more expensive the pipework gets.
 
Otherwise, for a 1500lph pump pretty much any pipe should be fine over half an inch, but again, redundency is key, as it only takes one snail to get into the overflow to kill a small bore pipe.
 
Chart here is useful. You'll want the green column for gravity feed.

 

[Reeferbro]

How many holes are you going for? The more the bigger the overflow, but the more redundancy and the more options to silence it, however the more expensive the pipework gets.
 
Otherwise, for a 1500lph pump pretty much any pipe should be fine over half an inch, but again, redundency is key, as it only takes one snail to get into the overflow to kill a small bore pipe.
 
Chart here is useful. You'll want the green column for gravity feed.

I will probably use 2. Will I need 2 seperate overflow boxes if I have two holes or could I have one larger overflow box with both holes in it?
Cheers

 

[DrRob]

Whichever you prefer. I have 2 outlets in one overflow. 1 below the water level with an open end (well, there's a grill over it, but it's otherwise open) and a tap to restrict the flow so that a tiny amount of flow goes down the other standpipe, which I tend to leave with an opening (above water level) to air (like a durso with the top opened). Creates a relatively silent system that has capacity to take a lot more water but is noisy at it if it uses much of the second pipe, so if anything blocks, you get noise to warn you.

 

[Reeferbro]

Ok cheers now I just need to find someone to drill my tank!