sensor alarm during water change

[TehBrainz]

So I've made the next jump in GHL implementation on my tank by adding a Maxi 2.2 for water changes. I've got the system set up to run using a high and low float switch in my sump and have leak tested and successfully ran 3 water changes. Woo!!

I seem to be running into an issue with my sensors still sending alarms during the water change, even though I've enabled "No alarm on water change" in each sensor's settings. Am I missing something else? This isn't too annoying at the moment as I'm manually triggering the water change and keeping an eye on the process until I feel comfortable with the system, but when I set an auto start I won't want to receive the alarms the entire water change.

Thank you,
Brian

 

[Dave-T]

I don't have an answer, but I do have a workaround. If you remove water and add water at the same time, then your level sensors will not be triggered. that's what I do. It will have minimal effect on the amount of water that is actually replaced relative to what you would get if you removed it and added it back in separate steps. But if you want to do it, your way, keep in mind that you need to turn off your ATO during the water change.

 

[TehBrainz]

I don't have an answer, but I do have a workaround. If you remove water and add water at the same time, then your level sensors will not be triggered. that's what I do. It will have minimal effect on the amount of water that is actually replaced relative to what you would get if you removed it and added it back in separate steps. But if you want to do it, your way, keep in mind that you need to turn off your ATO during the water change.

I initially was going to set up the process how you described it, but I felt a bit nervous relying on the calibration of the pumps with two different runs of tubing. At this point I felt relying on the sensors to trigger the pumps on and off was a "safer" approach.

I do have my ATO turned off until my "high" sensor has tripped and have an alarm for excessive time for the WC that is ~10mins beyond what I timed in my first 3 runs.

 

[TehBrainz]

Another question regarding the use of the Maxi...

I've seen positive AND negative values when looking at the amount dosed. Any idea why that might be?

For example, the AWC from this morning's automations shows at 1AM -3126.9ml in 1029s with 4AM showing 3067ml in 921s. Why would one be negative and the other positive when they are run off an automatic schedule and are both the same pump head moving in the same direction?

 

[Dave-T]

That’s a bug. I think it’s caused by integer overflow - basically the memory the program uses to store the numbers isn’t big enough. If you want to see the correct values, you need to export the data into a spreadsheet and do the math yourself.

 

[TehBrainz]

That’s a bug. I think it’s caused by integer overflow - basically the memory the program uses to store the numbers isn’t big enough. If you want to see the correct values, you need to export the data into a spreadsheet and do the math yourself.

So silly question. How would one export the dosing pump data? GCC gives you an option to export measurement data from the sensors, but I don't see a way to do this with the dosing pumps

 

[Dave-T]

If you look at the history for a dosing pump, there's a button at the top to switch from graph view to data view. Switch to data view, then there's an option "csv export". That will export the data to a csv file that you can open with excel or google sheets.

 

[TehBrainz]

I've done that export and I'm still showing negative and positive values for the "Saltwater Remove" pump. I highlighed the positive values to help stand out more. When looking at the absolute value and calculating the ml/min the positive values all seem to come to 199.8ml/min while the negative values vary. This is strange, but matches with the set speed of the pump. Perhaps I should calibrate this pump as I didn't worry too much about the rates since it was removing the water until the float switch was triggered.




"Saltwater ADD" pump does not show this same anomaly, but I calibrated and verified accuracy (since the output is right next to my tank and the remove is going right into the drain).




I will recalibrate the pump removing water based on this data and see if that helps.

-B

 

[Dave-T]

If you multiply, the dosing rate of the pump by the number of seconds that it ran, you can calculate the true amount that was dosed.

 

[TehBrainz]

If you multiply, the dosing rate of the pump by the number of seconds that it ran, you can calculate the true amount that was dosed.

So I did the reverse to confirm the rate of the dosing pump based on the outputs of the data dump.

When I export the data to a CSV file, GHL provides mL and duration in seconds. Dividing the two and converting to minutes is what I have in the far right column.

On Sunday, I calibrated my "Saltwater Remove" pump (thinking the calibration could be what was providing the interesting results.

I determined a calibrated rate of 275ml/min and set the speed to match. I verified the accuracy by testing 50ml and 20ml doses as highlighted at the bottom of the table. Calculating the ml/min from this confirmed the 275ml/min set point. I then had to dose water back into the tank as I basically ran a small water change during calibration (woohoo for extra WC's!), hence the 1500 and 500ml's before my auto WC's kicked back on.

Since Sunday, I've had 3 nights of auto WC's and with a manual "test" WC on Sunday for a total of 10. Only one instance had this "positive" dose on 1/23 @ 4AM which calculated to a 47ml/min dose. Another interesting data point that popped up was this random occurrence of a 3.2ml dose for 1s on the "Saltwater ADD" pump.

 

[TehBrainz]

@Lasse , have you seen anything like this before? Any thoughts?

 

[Lasse]

@Lasse , have you seen anything like this before? Any thoughts?

Nope - but I have notice that my Maxi not report the same numbers as I have in my table. Its for my Zooplankton feeder that both take up water from the sump (negative amounts) and what it pumps out into the return pumps intake

Time	Dos table	Reported doses
07:06​	-500​	-498,9​
09:15​	50​	49,9​
10:00​	50​	49,9​
11:00​	50​	49,8​
12:00​	50​	49,8​
13:00​	50​	49,8​
14:00​	50​	49,8​
15:00​	50​	49,8​
16:00​	50​	49,8​
17:00​	50​	49,8​
18:00​	50​	49,8​
18:36​	-500​	-497,5​
19:03​	575​	572,2​
20:16​	-500​	-497,6​
20:48​	575​	572,2​
22:36​	-100​	-99,5​
23:00​	150​	149,2​

I can live with this but send in a ticket on your findings

Sincerely Lasse

 

[TehBrainz]

Nope - but I have notice that my Maxi not report the same numbers as I have in my table. Its for my Zooplankton feder that both take up water from the sump (negative amounts) and what it pumps out into the return pumps intake

Time	Dos table	Reported doses
07:06​	-500​	-498,9​
09:15​	50​	49,9​
10:00​	50​	49,9​
11:00​	50​	49,8​
12:00​	50​	49,8​
13:00​	50​	49,8​
14:00​	50​	49,8​
15:00​	50​	49,8​
16:00​	50​	49,8​
17:00​	50​	49,8​
18:00​	50​	49,8​
18:36​	-500​	-497,5​
19:03​	575​	572,2​
20:16​	-500​	-497,6​
20:48​	575​	572,2​
22:36​	-100​	-99,5​
23:00​	150​	149,2​

I can live with this but send in a ticket on your findings

Sincerely Lasse

Thanks @Lasse . I've put in a ticket.

Part of me is indifferent of what sign the results are as long as they are accurate values, but I'm also very curious as to why schedule doses are negative and manual doses in the same setup are positive.

 

[Dave-T]

Like I said, the problem is with an integer overflow in the math that the GHL software does internally. It's a programming bug. It can't deal with the large numbers that the maxi doser produces. The software was probably only tested with the regular doser.

 

[TehBrainz]

Like I said, the problem is with an integer overflow in the math that the GHL software does internally. It's a programming bug. It can't deal with the large numbers that the maxi doser produces. The software was probably only tested with the regular doser.

I think I grossly overlooked your comment with the fact that I hadn't calibrated the pump at all so I felt I was partially to blame with not "completing" the set-up.

Interestingly, when I manually dose 1500ml vs. schedule dose of 1612ml (per my data) the issue comes up. My one positive value during scheduled dosing was with 1353ml so perhaps the limit is between 1500 and 1612ml.

I may try to simulate a 1650ml water change by activating each pump separately this evening to see if that provides negative results while I wait on the ticket to be addressed.

 

[Lasse]

Thanks @Lasse . I've put in a ticket.

Part of me is indifferent of what sign the results are as long as they are accurate values, but I'm also very curious as to why schedule doses are negative and manual doses in the same setup are positive.

In my table is the negative readings real - the pump goes backwards in these occasions

Sincerely Lasse

 

[TehBrainz]

In my table is the negative readings real - the pump goes backwards in these occasions

Sincerely Lasse

That makes sense, one direction positive with pump in reverse being negative.

I hope to test and verify the programming bug Dave mentioned with a manually activated water change this evening.

The rest of the system is working as designed for my water changes, so I'm still smitten with the process. I'd much prefer to do small auto water changes every day as opposed to lugging hoses through the house and worrying about the cats getting out!

 

[Dave-T]

This explains the type of bug I'm talking about:

Integer overflow - Wikipedia

en.wikipedia.org

 

[TehBrainz]

This explains the type of bug I'm talking about:

Integer overflow - Wikipedia

en.wikipedia.org

Read through that page to get a better understanding. Totally makes sense.

I'm not sure why I was so dense when you were suggesting to determine actual dose by multiplying the doser rate by the time of the dose. That worked perfectly and matched when I compared with estimated volume of water changes based on geometry of the return chamber. That's what I get for trying to multitask work work with problem solving of equipment I'm not yet familiar with.

When I estimated volume dosed based on this calculation I have a stdev of 130ml or 0.7min (CV of 3.25). Pretty darn good IMO. My "Saltwater Remove" has a larger variation with a stdev of 1205ml and 4.4mins (CV of 25.16), but that is due to the fact that the starting point is not always constant, whereas, the low level and end level are fixed.

 

[Dave-T]

What I did to calibrate my pumps for auto water change, was to dose a large amount, like a gallon, from each dosing head over and over, then took the average rate to determine how long to run the pumps for. Then I run them for a certain number of minutes each as controlled by timers. I do an auto water change of 5 gallons a day.