Does supply alter at different times of day ?

[hosburger]

Hi,

Please bare with me I am not an Electrician ! A friend of mine has a marine fish tank that has an electric pump circulating water ( sort of anyway ). It appears that towards the later part of the day the pump pumps more and levels in the tank alter. My question is - do our household supplies flutuate at all in any way ? Perhaps frequency changes with load/demand on grid and perhaps speeds up the pump ?

I might be totally way out here but seem to remember something about this kind of thing.

Cheers

 

[wingcoax]

Any difference would not be worth bothering about.

 

[flameport]

Frequency will vary slightly during the day, the changes can be seen here:
http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Frequency/Freq60.htm
Note that the changes are very small, that graph only shows a maximum of +/- 0.8%

The voltage will vary, this is dependant on the loads in your local area. Generally, as demand increases, the voltage will drop. If it drops too far, automatic equipment will adjust the voltage upwards, so you will get 'steps' in the voltage. The reverse applies when demand decreases.
You can often see this as incandescent lamps (old lightbulbs) will change in brightness slighty.

However all of this is not likely to have any significant effect on the flow rates of a pump.

 

[ban-all-sheds]

Please bare with me

In this weather?

Are you mad?

 

[timtheenchanter]

seeing as the pump needs to be full of water to work, as does any filter box external to the tank, I dont see how the level can alter noticably, it MAY pump more water, but seeing as water doesnt get compressed, the flow rate would increase, unless there is some sort of multi tank setup feeding one another.

 

[Stoday]

Please bare with me

If you are a young lady I would be delighted to bare with you.

I can see no reason why changes of circulating pumping speed or pressure should alter the water level. Maybe the fish drink more.

 

[wotan]

Over his head I fear....bear with me bare with me

 

[aptsys]

seeing as the pump needs to be full of water to work, as does any filter box external to the tank, I dont see how the level can alter noticably, it MAY pump more water, but seeing as water doesnt get compressed, the flow rate would increase, unless there is some sort of multi tank setup feeding one another.

Most marine setups will have a sump.

 

[timtheenchanter]

isnt the sump full though? ie no air space above it, the one I have seen/used all have been (although they were for fresh water tropicals) any air tended to end up in the pump, and causing no flow.

 

[chapeau]

It appears that towards the later part of the day the pump pumps more and levels in the tank alter

If you wanted to check the observation then you could send the water into a bucket and time how long it to fill it up. You would expect the time to differ depending on time of day.

You might also do this with high current drawing electrical equipment turned on. It might be that eg you are cooking at that time and this affects the local house voltage which affects the pump.

Or it might just be the fishes having their last pee before they go to bed.

 

[aptsys]

isnt the sump full though? ie no air space above it, the one I have seen/used all have been (although they were for fresh water tropicals) any air tended to end up in the pump, and causing no flow.

No, they can simply be open topped. A weir in the aquarium prevents the aquarium emptying all of it's contents if the pump can't keep up.