View Full Version : Thinking about having my 75 gallon drilled

02/15/2006, 12:36 PM
75 Gallon fish only.
What are some suggestions on where to have the holes drilled? How many? And most importantlly what size?

What i thought was 3 holes
2 inlets on each corner and one outlet in the center.

Is this over kill or do i have it completelly wrong?

Will this be quieter than useing an overflow box?

Thank You for the help

02/15/2006, 01:14 PM
I would do 2 drains and just have the returns come over the top. I will be drilling my 150 in a month or two and plan on drilling for 2 1.5" bulkheads. For a 75, I would think that 2 1" bulkheads would be sufficient. You could always setup a durso type standpipe right where the pvc runs into the bulkhead to keep things quiet. It all depends on what size return pump you use as to how loud the drains are.

02/15/2006, 01:24 PM
I would go with 2 holes in each overflow 1 for drain and 1 for return. While you are having it driledyou might want to drill holes for a Closed loop.

02/15/2006, 01:26 PM
I too am in the same process of deciding if I should go with an HOB overflow or drill my 75. From what I can gather, the holes would be drilled into the back of the tank as far down a possible. You would then creat the "overflow" box inside the tank and silicone (is that correct?) it in place. Then you can place the Durso standpipe in the overflow with a 90 elbow at the bottom by the bulkhead.

The questions I have are what size holes - I know its based on the return pump - so I have a Mag 9? Are two standpipes needed or is just one ok - I'm planning one overflow spot? Why would you use a spraybar?


02/15/2006, 01:26 PM
Make some durso standpipes and it will be so much quieter than a Hob overflow. With a CL you wont have any powerheads in the tank.

02/15/2006, 01:32 PM
your probably going to pay 20$ per hole.

for that reason if your slightly mechanically inclined you'll be cheaper to order a drill off ebay for less than the price of a single hole and can then go to town.

if your not comfortable with that though, my 75 has 1 1.5" hole for a drain, and then I put 2 returns over the side.

02/15/2006, 01:48 PM
I'd drill a 1.5" drain and 1" or .75" hole for supply.

You can do an internal vertical overflow box or an internal horizontal overflow box. I did a vertical box, but would probably go horizontal if I had to do it again.

for the box itself, figure up some dimensions and call a few local glass shops and give them the dimensions. I found my glass for $12.

02/15/2006, 02:12 PM
I found this option and like it better - don't know ho well it works or what the problems with it are, but thats why we are here.

He placed two bulkheads high on the back of the tank then put two 90 elbows facing up with screening over them as the drain pipes - the water overflows into them and then out the bulkheads and into a sump. The attached pic shows the back of the tank and the means of making it a bit quieter.



02/15/2006, 02:25 PM
That's exactly how I planned on doing mine

02/15/2006, 02:33 PM
Cool - Thanks seems easy enough.


02/15/2006, 02:43 PM
jet is that a quiet setup? What do you have the caps on the pipes for?

02/15/2006, 02:48 PM
Its not my setup, just one I found when looking into how to run my overflows. From what I can gather the caps are on the pipes for the same purpose you put the caps on the durso standpipe - a hole is made into the top of the cap and this allows the air to escape thus making the units quiet.


02/15/2006, 02:57 PM
it will be more effective at surface skimming if you built a horizontal box around it though. rather than just 2 90degree bends and maybe 1.5" diameter for the water to fall into; leave the 2 bulkheads open and add a box around them, the longer the better, but only as deep as nescessary to fit the bulkheads.

longer overflow means you skim the surface better, which will make your skimmer work better and reduce the equilibrium point if the sump pump turns off.

02/15/2006, 03:13 PM
I'm not certainly not an expert, but check out the thread on horizontal overflows in Anthony Calfo's Forum, All Things Salty (http://www.reefcentral.com/forums/forumdisplay.php?s=&forumid=339). This is the way I intend to do mine.

The whole idea is to get a thin layer off the top of the tank. Just sticking in a bulkhead and putting a strainer on the end (whether turned up with a 90 or not) will not do a very good job of skimming the top layer.

Also check out the "drain/overflow size calculator" on the RC main page. You can use the drain size it suggests or go one size smaller and use 2 for redundancy incase one gets plugged.

02/15/2006, 03:29 PM
I have been thinking about building acrylic boxes and adapting them to my bulkheads.