Aquarium Overflow

[Chud]

Hi there

I'm in the process of trying to design and construct an overflow system for our newly obtained 180 litre Tropical Marine tank because drilling a prebuilt glass tank is not something I want to risk!

What I've got so far is below:

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This is my diagram which is based on the below which doesn't quite look right to me...

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Basically the idea is that water overflows from the main tank into the overflow system - which then overflows again into the 10gallon sump underneath. Water is then returned to the main tank via a submersible pump - the pump effectively regulates the flow between the sump and the main tank.

At the moment I'm thinking of using guttering downpipe for the overflow chambers (dk grey in my diag) with 22mm speedfit pipe for the siphon tubes (lt. grey). Alternatively I was thinking of using washing machine outlet pipe for the siphon as it will bend easily over the rim of the tank without kinking - the only problem being the fitting of an air bleeding tap at the top of the siphon.

My questions are as follows
1) can you get stop ends for downpipe - solvent weld is pref as the overflow outside of the tank is going to contain a few litres of water and if the bottom falls out will empty and then by virtue of the siphon will empty the tank.
2) relates to the above - are solvent welded pipes suitable for potable water - or will the 'glue' poison the fish/corals etc.?
3) How tight a bend can you put in 22mm speedfit pipe - I presume you heat it in a bowl of boiling water etc and when floppy bend to shape - is this right and will the pipe stay bent after it's cooled?

Cheers

Richard[/img]

 

[Steve]

I dont understand. No aquairium I've seen has needed such a construction. Or they'd be built as such. With a hole etc. Why cant a self-contained pump/filter be used within the tank?

 

[Spark123]

I think the pipe you have drawn to the sump is too high up on your drawing, it needs to be lower down for the syphon to work. The water level in the tank should not drop below the level of the first chamber, if it does then the water level in the first chamber will drop down and level out with the water in the 2nd chamber at the height of the top of the pipe to the sump.
Another issue would be how to keep the syphon working, if it stopped would the pump cut out before the tank overflowed?

 

[Jasonb]

I don't see why you need to overflow the tank. A pipe with a strainer leading to the pump then from pump back to tank via filter will do. You just need to prime the pump the first tim eyou use it.

1. You can't get stopends for rainwater pipe, better to get some UPVC pressure pipe which is OK for fish and they do stop ends

2. See above

3. You can use an elbow to get a tight bend otherwise its about a 200mm radius. Try to avoid tight bends as the friction losses add up and reduce the flow of your pump

Jason

 

[breezer]

why exatcly are you doing this?

as others have said never seen a tank with an overflow, but i have seen a tanks that overflow into eachother, but its a safe bet they were built like it.

 

[Chud]

OK to answer a few questions

This type of set up is common on saltwater aquariums esp reef aquariums - if you go into your local aquarium shop and look at a decent size reef tank you won't see heaters, big filters etc just probably a few power heads and an inlet and outlet to and from the sump - the tank will likely be drilled to accomodate these. The drilling is generally done before the tank is assembled hence my reluctance to go down this route.

Overflow boxes (or chambers) replicate the effect of having a drilled tank and are complicated to ensure that in the event of a power cut the system will not syphon the tank dry and overflow the sump or when power is restored drain the sump and overflow the tank.

I've done a couple more diagrams which should explain below
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Sump filtration is very effective for a number of reasons:
1) increased water volume - makes for healthier water and easier maintenance - if anyone tries to sell you as a first timer a 20 gallon saltwater tank you should smell a fish... My main tank is 180 litres, the sump another 50 litres (ideally should be about 70-90 but don't have the space) - therefore total volume in the system will be c. 230 litres

2) when a wet/dry filter tower is used above the sump extremely efficient aerobic biological filtration is achieved. (see below)

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3)Most tank equipment can be located in the sump cutting down on unsightly wires, tubes etc. in the main tank.

Attached/In my tank I will have:
1 Heater
3-4 powerheads to create water currents around the corals etc.
Fluval External filter inlet and outlet
Overflow (inner) chamber

In (or connected to) the sump I will have
1 Heater
1 Powerhead (to return water to tank from sump)
Wet dry filter tower
Plenum sand bed (biological filter)
TMC Vecton UV sterilizer + powerhead
Caulerpa macro-algae
Protein Skimmer