Aquarium waterlevel problems

[aquarium fanatics]

Hi!
I have a problem with my aquarium level adjustment. I have automatic level adjust but I dont know why, but the level is wandering about 7cm from max to min and it should be only 2cm. The circuit I'm using is attached, so if anybody can help me I would be very happy, now my aquarium water is draining on the floor now and then. Please can somebody help me?? I use Crouzet millenium 3 to process the analog info I get from my circuit.

[justin thyme]

I'm afraid it is not possible to see from the circuit diagram how it is supposed to work!

Is one of the pressure switches supposed to detect the 'lowest' water level and to switch on the water inlet, and the other pressure switch to detect the 'highest' water level and switch the water off?

Maybe the pressure switches are too far apart (presumably one is above the other - but at a certain distance apart) or there is some other circuitry (that you haven't shown here) that has the 'on/off' hysteresis set too high.

[aquarium fanatics]

Hi!
I'm sorry that I have not put everything here but the system works so that I have logic controller where I have put the hysteresis in the logic. I have noticed that the problem is in the circuit and I think it's something to do with electrical interference, because when I move the circuit it changes. There is two similar circuits because the other one is "backup" to the other one. I think I should do some electronic protection or something like that??!!

Thank you much for being interested in the case!

I'm sorry for bad explanation, but my english is not so good.

[aquarium fanatics]

I have made a little better circuit drawing and it's attached here.

[justin thyme]

There is not enough information!

1) You could try putting a 0.1uF beween 0V and each logic input on the Crouzet.

2) If you remove one of the pressure switches (I assume that one of them is the 'backup') does it work correctly?

3) What exact model of Crouzet are you using?

[anneo]

Let me try to understand,
both pressionsensors inactif:fill up
both sensors actif:stop filling
only one then level is ok
The difference in pressure are quite small,you need 10m for 1atm.
So when it rains outside (low air-pressure) you get your floor wet inside
Anne

[justin thyme]

I think Anneo is explaining that the shallow water level does not put enough pressure on the sensors, therefore atmospheric will have an affect. Atmospheric pressure varies a little every day, and therefore the water level will also vary.

It does seem reasonable to expect an atmospheric affect (although I do not know how much the affect will be) but it doesn't explain why you get problems when you move the circuit.