If you turn off your MH lights with a Temp command...

[johns]

If you turn off your MH lights with a Temp command like this:

If Temp > 83, Then LT1 Off

Do you have to have a command like this:

Max Change 010M Then LT1 Off

Is that second command needed to get it to fire again, or will it fire on its own when the temp drops back down? Or are people using this second command to keep the ballast from trying to fire on, over and over again?

My ballast automatically waits about 5 minutes before it fires again on it's own - is that sufficient if I use the top command only?

Confused.

 

[clp]

You want the Max Change command in there so that the ballast is not repeatedly turned on/off. In your example, if the temperature was fluctuating between 83.1 and 83.0 then the ballast would turn on/off frequently.

Curt

 

[johns]

But the way I understand it, if my ballast turns off, it will never fire again on its own for 5 minutes.

For what it's worth, this is a Bluewave VII ballast. And if I ever turn the lights off and then turn them on again quickly, nothing happens for about 5 minutes and then they fire up on their own once the time has passed.

I dont mind adding the command, but want to understand that it has a purpose.

 

[clp]

I don't think you want to cycle the power on/off quickly to the ballast even if it was the appropriate restart circuitry. Frequent power cycles may damage the ballast. I recommend that you put the statement it.

Curt

 

[Aquaduck]

I do too. Your ballast could hypothetically turn on and off every 5 minutes depending on your temperature fluctuations. Adding the MAX command is not going to hurt anything and will ensure that when your lights do come back on they will stay on for a while because your tank will have had a chance to cool a bit. I have mine set to stay off for 15 minutes if I exceed my "comfort" level.

 

[johns]

OK. Points well taken. Thanks.

So my next question is - What is the optimal amount of time for the light to stay off before firing again then?

Aquaduck-you use 15 minutes. Is that pretty well accepted as the norm? Also, I dont understand your statement will ensure that when your lights do come back on they will stay on for a while because your tank will have had a chance to cool a bit

How does the command ensure that the lights will stay on for a while? Wont they just stay on again until the temp limit is exceeded? Or am I missing something again? What happens then if it tries to fire after the 15 minutes is up but the temp still exceeds the limit.

 

[clp]

I use 30 minutes in the max change on my tank. I would make it a larger number not a smaller, as your lights shutting down indicates something is probably very wrong with your tank. The lights will come on as soon as the temperature drops and the Max change timer has expired. Yes, the lights will go off again if the temperature is exceeded. If the temp is still too high after the max change timer has expired they will stay off until the temperature drops.

Curt

 

[johns]

thanks again:

Last questions I think. Is this the right command for a 30 minute wait:

Max Change 030M Then LT1 Off

Still struggling with what the 'Off' means

What happens if you enter it like this:

Max Change 030M Then LT1 On

 

[clp]

The 'off' indicates that it should be 'stuck' in the off state for 30 minutes. Use this:

Max Change 030M Then LT1 Off

If it is 'Then LT1 ON' then must be on for at least 30 minutes before it is allowed to shut off. You don't want this.

Curt

 

[Aquaduck]

OK. Points well taken. Thanks.

So my next question is - What is the optimal amount of time for the light to stay off before firing again then?

Aquaduck-you use 15 minutes. Is that pretty well accepted as the norm? Also, I dont understand your statement will ensure that when your lights do come back on they will stay on for a while because your tank will have had a chance to cool a bit

How does the command ensure that the lights will stay on for a while? Wont they just stay on again until the temp limit is exceeded? Or am I missing something again? What happens then if it tries to fire after the 15 minutes is up but the temp still exceeds the limit.

I use 15 minutes. It works for me on my 90 gallon. Larger tanks may want longer off times to give the large volume of water time to cool.

For example... your tank temp is too hot, say 83 degrees and you have the lights turn off at this temp. The lights will have to stay off for 15 minutes due to the MAX Change command. During this time the tank should start to cool off. So the longer the lights are off the cooler the tank will get. When the lights come back on after the 15 minute timed shut-off it will take a longer period of time for this light to warm the water back to 83 degrees thus ensuring the lights will not be switched on/off many times.

Now if something else is wrong with the tank like a stuck heater then the light should never come on. My controller has the alarm set to go off if the water temp goes 1 degrees over the point at which my lights go out. I figure if the tank is still warming up after the lights are off there is a serious problem.

 

[johns]

Good ideas. Thanks