Which water sensor to buy ?

Good morning, I'm from France and I have a request for my project. I need to manage the level of water bewteen two tanks (the water will fall down from one to the other) . So considering that the quantity of water will not change, I will use two sensors, one in each tanks.

I was thinking to connect them to two analogic inputs and get after low/high signals to activate the water pump. But I am not sure for the components, severals kinds of water sensors exist maybe you can advice me some will fit on the Arduino card (Mega) ?

-hope my english is understanble-


I'm from France

That's ok, we'll still try to help. 8)

If the water is going to fall down from one tank to the other, why do you need a pump?

I think we need a sketch of what you mean.

Thanks for your answer we are creating a "curtain water light" https://www.youtube.com/watch?v=hJh6ykiZJ2Q //example So it will be like a fontain, we have to keep the water Here I made a draw of our system :

Uploaded with ImageShack.us

Ah ok, the water falls from the top tank to the bottom and the pump returns it from bottom to top...

I would be inclined to try this first with no control, but to just size the pump to match the flow of water and leave it running. As long as the lower reservoir is big enough to make sure the pump intake is always in the water, and as long as you add water from time to time to replace that lost by evaporation and wind, it might be ok?

That really is no different from my garden fountain where I had a birdbath standing in a small pool.

hm the problem is that we will control each solenoid valves one by one so the water flow will change and also the upper tank will be little so we cannot let the pump runs everytime

for example, if only one solenoid valve is opened the pump has to stop till the water on the top isn't enough

I'm not sure I'd put any sensors in the lower tank, but I'd have two in the upper tank, a high and a low level, and the job of the control circuit would be to run the pump appropriately so the water level in the upper tank is always between the two. If the flow through the solenoid valves is just by gravity feed, then regulating the water level in the upper tank to some fairly narrow range would have some advantages in maintaining consistent flow through the valves.

On second thought, a low-water-level sensor in the lower tank might be good to detect water loss due to evaporation, leaks, etc., but wouldn't be an absolute requirement.

What sensors have you found so far? I might be tempted just to fashion my own from stainless steel rod or something similar.

There seems (as always!) to be a range of techniques from homemade to fancy commercial.

The 'Usual" Float sensor is just that, a magnet embedded in styrofoam. It triggers a reed switch when high or low fluid level is detected. I used them for liquid fertilizers, reservoir sensing and dual tanks of many different types.. Jack Christensen Was Spot on in his analysis of the sensing requirements including the lower tank warning sensor. The upper tank sensor could be one assembly with 2 reed switches, One for the upper shut off sensor and the other lower one for pump start The lower 'supply' tank needs a fill sensor to warn of low water level.


@Jack Christensen Yes we thought also about two sensors in the upper tank and also two for the lower.

@JimboZA Our first idea was to use float sensors and also pressure switchs

@Docedison I'm not sure to understand well, you mean two float sensors in the upper tank and can you be more precise one the term : "a fill sensor " ?

Finally I can use two of them in the upper tank, one will be ON when there will be too much water,stopping the pump the other will be OFF when there won't be enough water, starting the pump that will keep a constant level except if we have a water leak and in this case we will have the third sensor which will be OFF when the minimum level of water is reached in the second tank stopping the system.

Now for the components, we have to supply them with a voltage as 5 V and get back this one through the analogic inputs ? These three float sensors http://uk.rs-online.com/web/p/level-sensors-switches/0519242/ are fitted ?

If you are using just ON/OFF switches/sensors, you don''t need analogue inputs, use the digital ones. Just make sure you are using the right pull up or down configuration.

I've used some cheap float switches from ebay, and they worked fine.

@ h3ll0

I am wondering which valves you are using for the release of water. I have been after some quick/direct acting (i.e. non-diaphram) solenoid valves which can withstand high repetition over a long period of time without failure.

@pgmartin Yes we will use pull down configuration I guess @lemming we bought one of this valve : http://uk.rs-online.com/web/p/solenoid-valves/0342017/ to try how is going