Indoor vertical garden-noob help!

Hello guys!
This is my first post and i need some help.I am new to arduino and new to automatic controllers.
I constructed a small vertical garden that is hung on the wall and it looks like a painting. in the garden, of course, placed the plant.
on the lower side is located container in which is the water and a small submersible pump.
This pump is used for irrigation by forcing water into the upper end and collects water that flows back into container.it is a closed loop.
Pump is connected to a timer and periodicallygo on during the day.
Only need to top up evaporated water.
So my question is: is there anything in the market or can be made in DIY,which would be located in container ( Water level sensor? )
and that would take care when you need to refill the water ( SMS ?).Would also be good if the timer for the pump and sensor for light plugs into this.
Size of container in which is water is 10-15 cm depth and 12 cm width.
Sorry for my poor English...
Thanks for your help and suggestions!

It is definitely possible to measure water level in many different ways. There are pre-built options and DIY options.

Chsck out this thread: http://arduino.cc/forum/index.php?topic=99113.0

YOu might also consider using a moisture sensor to start / stop the pump - better than timer?

BartOS:
is there anything in the market or can be made in DIY,which would be located in container ( Water level sensor? )
and that would take care when you need to refill the water

Is the container big enough to use an ordinary float valve from a toilet cistern?

@djjoshuad - thanks for the link is very useful !!

@robtillaart - can you recommend any particular ?

@PeterH - I tried it already with this idea, but unfortunately the container is too small...maybe i try with small float switches ?

BartOS:
@PeterH - I tried it already with this idea, but unfortunately the container is too small...maybe i try with small float switches ?

I was thinking of something like this Fluidmaster Toilet Cistern Bottom Entry Float Valve 400UK074, which could be fitted in a small container. It wouldn't need to be installed directly into the lower container - if it's more convenient, you could add a separate container with one of these valves, positioned so that the water level is at the required level for your container, and connect the two via a link pipe or siphon.

You might want to look at the Vegetronix VH400 Soil Moisture Sensor - VH400 as an easy to implement water level sensor, but I think only up to 10cm. I have 3 of these and they work great for soil water content measurement, but will work for water depth, too. Milonetech has another product you may be interested in: http://www.milonetech.com/About_eTape.php. Good Luck!!