# Opinions for a overflow setup



## Jake101 (1 May 2018)

Hi,

I just got a good offer to buy a bit used 100L tank with a sump. However, I have no experience with overflows, so I would like to hear opinions from more experiences people concerning the setup.






As seen in the picture, there is a smallish overflow box inside made of glass, with a plastic comb. The drilled hole with a bulkhead is for a 12/16 hose. No other drillings made since the return comes to the tank basically same way as an external filter inflow hose.

I naturally have a possibility to get the tank drilled more if needed. The only major shortcoming that comes to my mind is the fact that there is no emergency outflow if, for some reason, there would be a block in the main outflow.

Any thoughts and ideas for improvement are well appreciated.

Edit: Concerning the size of the outflow hose/pipe in terms of the filtration volume per hour, the tank has been used for a non-CO2 setup, and I'll do the same.


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## Edvet (2 May 2018)

Should work, depending on fish size and comb size you could add a block of coarse foam to keep fish from passing.
Keep in mind of the volume needed to store in the sump in case of a power failure.


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## Jake101 (3 May 2018)

Thanks, @Edvet


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## zozo (3 May 2018)

Jake101 said:


> The only major shortcoming that comes to my mind is the fact that there is no emergency outflow if, for some reason, there would be a block in the main outflow.



Than the shortcomming isn't in the aqaurium drilling but in the sump design.. See this diagram it might explain it beter than words.



 

Obviously V3 drains if the tanks outflow gets blocked and V3 completely empties but can't overflow the tank because its volume is smaller than V1. Make sure it contains a pump with a thermal protection..


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## foxfish (3 May 2018)

That is a very small return, a more standard return would be more like 25 32mm. What is the actual size of the drilled hole?
Perhaps the box is designed to be used as a skimmer and could be  connected to a external filter. The problem with that  would be fluctuating water levels running the filler dry.
If you really want to run a sump I would consider drilling a larger hole but the design is not very good due to the pipe work exiting from the back of the box as this means the tank will have to have considerable clearance behind the tank!


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## Edvet (3 May 2018)

foxfish said:


> very small return


Depends on flow i guess. A lower flow non CO2 tank wil work. In my large tank i have 32 mm outflow.


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## foxfish (3 May 2018)

Yes of course but there are other factors like avoiding blockages & air locks.
If you intend to use 10 x flow & a spray bar return then 16mm id gravity feed will not carry much flow.
Also, having a overflow box in a scaped 100lt tank might not be very pleasing eye?


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## zozo (3 May 2018)

I can conferm a 25mm bulkhaed doesn't have much through flow by gravity only. I run my 60 litre outdoor tank with that and i'm pretty far under the 600l/h. Don't know the excact number, but it runs a 600l/h pump i have to decrease. Than i also use a mesh guard over the outlet this is also blocking a bit of flow. A sponge would block even more. For the 110 litre indoor tank with sump, runs on 2 overflows with a 14/16mm syphons connected with 25mm piping and i'm +/- 400 l/h turnover. I might be able to get some more to change the overflow design. But actualy for a 110 litre low energy tank and the fish is houses the 400l/h is sufficient.

i guess if the bulkhead in the hole is reduced to 16mm hose than Foxfish is probably correct, that it is meant as skimmer only and the previous owner likely used an extra overflow box.

And looking at the drawing and if there is a 16mm hose connected to that it wont do much good.. Because if you have a 16mm hose all the way down to the sump it'll suck a vacuum and slow significantly down.. It should have an air vent to run full capacity. Say you can change the bulkhead to make it 25mm or 32mm pipe, depending on the lengt down to the sump you would also need an air vent to prevent it from vacuuming and slowing down.





And indeed as Foxfish says that construction and very pleasing to the eye and next to that actualy completely redundant.. You could ditch the box completely and guard the bulkhead with a filter guard cap.


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## Jake101 (3 May 2018)

Thanks for the advice. So getting rid of the overflow box and installing something like this (assuming that the placing of the hole is suitable)?


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## foxfish (3 May 2018)

Yeah that would be great, it looks like a 32mm or even a 40mm fitting, so you would need the correct sized hole.


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## kadoxu (4 May 2018)

Jake101 said:


> Thanks for the advice. So getting rid of the overflow box and installing something like this (assuming that the placing of the hole is suitable)?


But... that's also an overflow box...


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## Edvet (4 May 2018)

kadoxu said:


> But... that's also an overflow box...


looks more like a bean overflow on the outside (in stead of a combed overflow on the inside)


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## zozo (4 May 2018)

Yes it indeed looks like a Bean? overflowbox for the outside.. But with a drillled tank you could also go straight down from the bulkhead with a $ 1.50,- knee and a pvc tube to the sump. I guess you'll have more than enough with 1 metre tube and maybe a few 45° knees to get around the corner. Than drill a little hole in the top knee at the highest point to prevent the tube from vacuuming.. Personaly i would give that a try first and safe the money for that box, you can still always buy it if you don't like the way it drains with just a drilled knee on the bulk.. In my personal experience ridgid tubing works a lot easier, looks beter if constructed propperly and if sized correctly never needs to be cleaned...  Flexible PVC hoses i always experience as a hassle..


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## kadoxu (4 May 2018)

Edvet said:


> looks more like a bean overflow on the outside (in stead of a combed overflow on the inside)


It's an overflow box...
Eclipse S - *Overflow Box*


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## foxfish (4 May 2018)

kadoxu said:


> It's an overflow box...
> Eclipse S - *Overflow Box*


Yes a very nice overflow box at that! As far as I can see, the box fits over the glass & somehow pulls water from the surface.
It has a main sump feed via the lower outlet & a secondary pipe in case any blockages .
I cant quite work out how it fits together but it looks like two main  separate components that are linked with the through glass fitting, one fits on the outside & the other fits on the inside of the tank?


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## zozo (4 May 2018)

foxfish said:


> I cant quite work out how it fits together but it looks like two main separate components that are linked with the through glass fitting, one fits on the outside & the other fits on the inside of the tank?



The bigger picture might clarify that you are correct.. 





That box in the tank is rather narrow, in a smaller pic it doesn't look like a box at all.. Both in and outside box are screwed on with the bulkhead in the hole of the tank.


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## Jake101 (4 May 2018)

Ok, the bulkhead with a filter guard cap seems like a good KISS solution. I contacted the previous owner and the box really is a surface skimmer with a small turnover rate pump. The main filter was a normal external filter. Aaaanyhow, there is not real need to use the sump, but now I got interested of it and there is probably no way out of this. Typical thing with this hobby, but I'll continue searching and reading to figure more things out. 

When setting up the thing in the future, I'll take care water in sump has also room in the main tank in case of blockage and that the pump doesn't get toasted if it pumps all the water from the sump. I guess the inflow needs also to be build so that it does not siphon more water from the tank than the sump can take in case of an electric blackout.


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## foxfish (4 May 2018)

It even comes with a hole saw!


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## zozo (4 May 2018)

Jake101 said:


> I guess the inflow needs also to be build so that it does not siphon more water from the tank than the sump can take in case of an electric blackout.


Yup, same story actualy, syphoning only occures in case of a vacuum.. Thus if you place the inflow bellow the water level and the pump stops, than prevent the vacuum by a small hole above the water level, still can be in the tank in case it drips. In this case only the tube contents runs back.. Of course this is another story if you drill the tank for an inflow bellow the water level. Than you need a return valve.

You can always use a return valve either way for example as close as possible to the pump. But return valves will always reduce flow..

Running a sump best practice is always choose a over capacity pump. And use a T splitter with a ball valve on it in the sump to regulate the outflow to the tank. Like this..




The valve fully open water runs back to the sump little water runs to the tank, close the valve a little, more water is pushed to the tank. Regulating the valve in the sump will regulate the amount of water to the tank. Valve fully closed is full power to the tank. This will have the least strain on the pump and is the easiest way to regulate the pumps capacity. Best part is you can make a TURBO sump, put a hose or whatever, but lead the valves outlet back to the sumps first filter compartiment. Than this water just is filtered once again.


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## Oldguy (27 Sep 2018)

zozo said:


> Than the shortcomming isn't in the aqaurium drilling but in the sump design.. See this diagram it might explain it beter than words.
> 
> 
> 
> ...



Very clear diagram. Have you thought about a float switch in the sump. You can get then to turn on or off either up or down or horizontal. [Still have not got round to wiring mine in, though moved away from a sump (no room) to an overhead 'dry' trickle filter. Very mindful of volumes, our area is prone to power cuts.


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## zozo (27 Sep 2018)

Oldguy said:


> Very clear diagram. Have you thought about a float switch in the sump. You can get then to turn on or off either up or down or horizontal. [Still have not got round to wiring mine in, though moved away from a sump (no room) to an overhead 'dry' trickle filter. Very mindful of volumes, our area is prone to power cuts.



Yes very often and realy would like to implement it. Getting a water line there aint a problem. I still have a few models at hand in case.. But for now i do not have acces to sewage near the tank for the emergency overflow for the sump in case the float switch valve starts to leak due to dirt (calcium etc.) build up.
Once i have sewage access i definitively will install one..  But that is for auto fill.. That would be mechanical valve in the waterline..

Since you talk about wiring i guess you mean a floater switch for the pump.?. Not sure. In case.. I tried and it doesn't work in practice. Because everytime the pump stops you will have some water running back into the sump. Constantly lifting the switch. Such a switch only needs a milimeter to disconent/connect. It will result in pump going on and off in a constant cycle. I experienced it up to once every minute, that's 60 x on/off during an hour. Over night, nobody present at the tank it'll be 6 hours? x 60 = on/off cycle of 360 x.. Not good for the pumps lifespan..


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## Oldguy (27 Sep 2018)

zozo said:


> Yes very often and realy would like to implement it. Getting a water line there aint a problem. I still have a few models at hand in case.. But for now i do not have acces to sewage near the tank for the emergency overflow for the sump in case the float switch valve starts to leak due to dirt (calcium etc.) build up.
> Once i have sewage access i definitively will install one..  But that is for auto fill.. That would be mechanical valve in the waterline..
> 
> Since you talk about wiring i guess you mean a floater switch for the pump.?. Not sure. In case.. I tried and it doesn't work in practice. Because everytime the pump stops you will have some water running back into the sump. Constantly lifting the switch. Such a switch only needs a milimeter to disconent/connect. It will result in pump going on and off in a constant cycle. I experienced it up to once every minute, that's 60 x on/off during an hour. Over night, nobody present at the tank it'll be 6 hours? x 60 = on/off cycle of 360 x.. Not good for the pumps lifespan..



Very good point about the sensitivity of a float switch, procrastination about not fitting one was a good thing. My last tank had a sump with an overflow to a large garden, drilled through the house wall. Now moved, different house, different tank but still a large garden. If only I could get the water to flow uphill Lol.


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