75 gallon Reef Tank Overflow and Return Layout

[WatchBrowns]

After many hours of research I have decided to move forward with drilling my new 75 gallon (48x18x21) marineland tank and install an Eshopps Eclipes S overflow box. Mainly due to the peace of mind in not potentially losing siphon and flooding our newly renovated basement.

I was also gifted a new Fluval FX4 canister filter so I have decided I am going to use for extra bio, additional water flow, and can be used as a media reactor if needed.

My 2 questions are:

1. Where should I plan to drill the overflow box? Left, right, center? Is one location better than another?
2. Where should my return lines be located from the sump and from the canister filter for the best flow? I also have a hydra and 2 current USA wave makers that will be stationed around the tank.

My current game plan was to have the overflow in the center (slightly off center due to the center bracing) and then the return lines on either end of the tank blowing back towards the center.

Any advice is appreciated!

 

[hoffmeyerz]

Make sure you check that glass, I have a 75gal Marineland tank as well and it is tempered glass. I'm not sure if Marineland makes any that are not tempered glass.

 

[WatchBrowns]

According to the Q&A section on Marineland’s website they say that only the bottom glass is tempered on the 75 gallon tank, so I should be good to go on the back wall. Fingers crossed…

 

[WatchBrowns]

Just confirming here. The back wall is not tempered and I was able to successfully drill the overflow and decided to also drill a hole for a 3/4” return bulkhead.

 

[jdpeters]

Just confirming here. The back wall is not tempered and I was able to successfully drill the overflow and decided to also drill a hole for a 3/4” return bulkhead.

If you drilled a 3/4 inch hole for return I assume the return line is also the same diameter? I’m currently mapping out a 40b build so I’m curious

 

[twentyleagues]

If you drilled a 3/4 inch hole for return I assume the return line is also the same diameter? I’m currently mapping out a 40b build so I’m curious

Well the actual hole size for a 3/4" bulk head would be larger than 3/4" I think its around 35-40mm.
edited I had 1" on the brain

 

[jdpeters]

Well the actual hole size for a 3/4" bulk head would be larger than 3/4" I think its around 35-40mm.
edited I had 1" on the brain

Oh that makes sense that it would be larger. Thank goodness for forums, appreciate the response

 

[WatchBrowns]

JDPeters,

It will depend on the type of bulkhead you are using as well.

I used the ABS bulkhead from BRS that requires an 35mm hole.

BRS also has diamond hole saws you can buy on their site and they are a relatively good deal compared to local hardware stores or amazon.

I would also highly recommend a gasket on both sides of your bulkheads and plumbers tape on any threads to avoid minor leaks.

 

[jdpeters]

JDPeters,

It will depend on the type of bulkhead you are using as well.

I used the ABS bulkhead from BRS that requires an 35mm hole.

BRS also has diamond hole saws you can buy on their site and they are a relatively good deal compared to local hardware stores or amazon.

I would also highly recommend a gasket on both sides of your bulkheads and plumbers tape on any threads to avoid minor leaks.

Thank you. Is it common to double up on the gaskets? I’m sure the redundancy is probably good

 

[twentyleagues]

Thank you. Is it common to double up on the gaskets? I’m sure the redundancy is probably good

No that will cause more problems than not. 1 gasket inside tank wet side only.

 

[Cichlid Dad]

Also, if you're running a sump don't run a fx. It is not needed and only adds maintenance that you will eventually get tired of leading to nutrition issues in the future. No extra bio is needed in a reef tank with proper rock in the tank.

 

[jdpeters]

No that will cause more problems than not. 1 gasket inside tank wet side only.

That’s what I thought thank you.

 

[WatchBrowns]

What specific additional issues would be caused by a double gasket?

 

[WatchBrowns]

Would it make sense to run without the mechanical filtration and purely use it to run reactor media?

 

[bobnicaragua]

What specific additional issues would be caused by a double gasket?

It can cause issues tightening and getting a good seal.

I also agree that you don’t want the canister filter. You can throw media bags in the sump.

 

[RocketEngineer]

Thank you. Is it common to double up on the gaskets? I’m sure the redundancy is probably good

Two points:
1) Gaskets go on the flange side of the bulkhead, no matter the orientation. The threaded nut on a bulkhead does NOT seal. You need the gasket between the flange and tank to create the seal.
2) adding a second gasket adds MORE points for leaks, not less. The gasket is designed for a specific amount of give as it compresses. Leaking gaskets are more often the result of improper installation. Adding more things to the situation just gives more places for leaks.

 

[WatchBrowns]

Ah okay that makes sense and no argument on the gasket needing to be on the flange side.

I guess I was looking at the fact that overflow boxes like Eshopps come with double gaskets and the recommended installation is to sandwich the gaskets on either side of the glass.

As you pointed out though, it is a different situation since the external gasket on a bulkhead doesn’t actually seal at the threads while the 2nd gasket on the overflow box does seal between the glass and the external overflow box.

 

[twentyleagues]

Ah okay that makes sense and no argument on the gasket needing to be on the flange side.

I guess I was looking at the fact that overflow boxes like Eshopps come with double gaskets and the recommended installation is to sandwich the gaskets on either side of the glass.

As you pointed out though, it is a different situation since the external gasket on a bulkhead doesn’t actually seal at the threads while the 2nd gasket on the overflow box does seal between the glass and the external overflow box.

Yes you are correct the second gasket on the overflow to the glass is to keep the box from leaking water out of it. If you were to use a gasket on both sides of the glass in on a standard internal overflow tank the outside gasket would do nothing if there was one internally. I have always gone with a gasket on the inside on internal type overflows with the flange on the inside also. Just seemed to seal better for me instead of flange and gasket on outside.

 

[TaylorPilot]

Ah okay that makes sense and no argument on the gasket needing to be on the flange side.

I guess I was looking at the fact that overflow boxes like Eshopps come with double gaskets and the recommended installation is to sandwich the gaskets on either side of the glass.

As you pointed out though, it is a different situation since the external gasket on a bulkhead doesn’t actually seal at the threads while the 2nd gasket on the overflow box does seal between the glass and the external overflow box.

The inside gasket does two things. It keeps the water from leaking thru to the rear box in a power outage very slowly. With a prolonged return pump outage, the water would leak past the threads into the rear box, lowering the water level and possibly overwhelming the sumps capacity to hold extra water. It also creates a spacer so that the internal box isn't pressed tightly up against the glass, creating possible pressure points, if the box is completely flat (impossible because cast acrylic thickness can vary quiet a bit). The gasket sandwiched between the tank and the rear box is the only thing that keeps the tank from leaking. They do not put a gasket against the nut, because the friction makes it impossible to properly tighten it.

Adding teflon tape will not do anything except increase the chances of you splitting the nut or the bulkhead. Standard NPT (water/air tight threads) are tapered, and teflon tape is used to fill in any spaces and to keep metal pipes from galling when tightening them. I know a lot of people use tape on PVC fittings, but most manufactures recommend not using it, and instead use a pipe dope that is not hard setting.

For a standard bulkhead, you want a gasket on the flange side (whether on the air or water side) and nothing on the back. If it is leaking, either something is cracked or the tank has a chip in it.