Why is the water level in my display tank constant???

Hi guys,
Can someone please explain to me how and Why is the water level in my display tank constant???
How does the the wet/dry and return pump know how much water evaporated from the display tank and keep it running at the same level???
Thanks
Kevin

 

When you have a wet/dry filter or sump(any water volume lower than the tank), evaporation occurs below, in the lower water volume and all water in the display tank stays constant. So if you have a sump be careful that you top off the return section (lowest water level) as that is where evap. will occur. If the pump runs dry then the motor could overheat.

 

The water level in the display stays constant because it is determined by the height of the overflow drain. You still have evaporation, but the level will only change in the sump.

 

the overflow box keeps the display tanks water level. it wont siphon unless it has enough water to overflow through the slats. every tank is different my 55gal tanks evaporate 1-2 gallons a day. so I need to top off every 3-4 days or the pumps start blowing bubbles. some return pumps will stop if there isnt enough water to pump also.

 

It's really less complicated than you would think.

Just look at it this way:

Take a bowl full of water to represent your display and a cup of water to represent your return pump. If you were to poor some water from the cup into the bowl, it will fill to the top and begin to overflow. At this point the bowl can only overflow exactly how much you poor in.

This is how your tank works. As water is pumped up from the sump, the display fills to the top of the overflow and begins to overflow. At this point the water is only going to overflow exactly as much as the pump sends up.

If you have a hang on overflow, we would have to go through some fluid dynamics, and I've found it's easier to just accept that it works lol.

 

Topping off every three or four days is not a good idea. The idea is to keep your salinity stable meaning topping off every day. I can't imagine doing it every three or four days.

 

I don't mean to be difficult but i still don't understand why/how the water level is maintained in the display tank.
Meaning how does the pump sense how much water to pump up there if the level is constantly changing.

 

The pump is pumping water till the display "overflows" and then it stays at that level.

 

This might help.

 

The pump doesn't care. Your display tank holds water up to the point of the over flow. Above that level, any excess flows over the over flow. The pump just has to pump enough water from the sump to make up for the evaporation, any excess flows back down. If you want to see the level drop, turn off the pump and let the evaporation work as you seem to think it should.

Jeff