PH trubble

[Lasse]

Hi

I have some problems with pH measurements. I have a GHL system that controls two different water systems. The line-up is PB6-PB6-EXPBOX(1)-PH6-EXPBOX(2)-PB5-PB5-PROFILUX 3.1T. PB6-PB6-EXPBOX(1) control system 1 and EXPBOX(2)-PB%-PB% control system number 2. Each EXPBOX use the internal pH, redox and temp card plus 1 extension pH card. (EXPBOX(2) has also air temp/humidity extension card and 1 temp/humidity probe. The system 1 works perfectly and has done that for app 5 months. System 2 is started 1 week ago. Both are freshwater. All 4 pH probes was calibrated yesterday – using the same pH 7 and 4 fresh pH 9 calibration fluids. After calibration all 4 shows the same if I put all at the same spot in system 1 – they show the same value. There is a titanium heather working as a grounded probe in system 1.
The problems start when I put EXPBOX(2):s electrodes in system 2. The value start vary up to 1 pH unit and values was not relevant. After adding a titanium heather also in system 2 (just use it as a ground probe) – the readings became more relevant but has a funny pattern with changes of up to 1 pH unit in periods. For the probe attached to the expansion box internal pH card is the changes linked to illuminate channel 1. If that channel is on – the pH reading drops 0.5- 1 unit! And this is not linked to any attaching to a power bar outlet – just only linked to if illuminate channel 1 is on or off!!!!.
Now - I do not use Ill 1 for my lights – I use Ill 3 instead and that channel has not the same effect to my pH readings. I also use ill channel 2 without any problems. Now when I do not use Illumination channel 1 – this probe works.
However the second pH electrode (linked to extension the card of EXPBOX(2)) still can vary with up to 1 pH unit. Looks like the changes is connected to something like the other electrode but I have not found out what is the problem. I think that the first problem was different potentials in the systems – but the link to illumination channel 1 and the last example – I can´t understand. Can someone help me?

I use firmaware 6.14

Sincerely Lasse

[Matthias]

if you have only probes connected to the EXB -nothing else (like pumps, lights, sockets, etc.)! - is the symptom the same?

[Lasse]

Only probes are connected directly to the EXB - the rest is connected to the EXB through PAB and it is only pH probes connected to one of the EXB (EXB2) that does not respond as they should. For the moment (after I grounded system 2) the probe connected to the internal card works well but the probe connected to the extension card does not perform as it should. However – if I disconnect the titanium heather from the grounded power bar – the pH-reading rise 1 unit. I will log the probes during this night and will come back to you with the graphs. I will try to test with only the actual EXB connected and I will dismount the actual EXB and test to put the extension card in another slot.

I can understand that I probably have some electrical problems that cause my problems with the pH probes but I can´t understand how Illumination channel 1 can interact with the readings of the probe connected with to the internal pH card even if the channel NOT is connected with any outlet.

My setup is shown in the attaching picture – I have also a 4 channel dosing unit attached to S1-4

Screen Shot 05-25-15 at 08.05 PM.JPG

The picture do not show the real order – its like this:
SMS unit -> Profilux 3.1T -> PB6 -> PB6 -> EXB 1 -> PH6 -> EXB2 -> PH5 ->PH5
Attached to the different power bars is 2 pcs 1 kW titanium heather, 7 Jebao wave makers RW-20, 7 pcs Jebao DC 1200LV, 6 pcs 10 W LED lighting. 6 feeding machines
Each power bar (and power hub) have is own circuit 230 V – 10A. The two EXB and the dosing unit is connected to the same circuit 230 V – 10 A. The 3.1 T is connected to an UPS and the SMS unit is connected to a transient protection. The cover of the titan heather is grounded through the grid and serve as a ground probe.

I will also try to disconnect my 3.1T from the UPS and see if it will change anything

Sincerely Lasse

[Lasse]

More tests

I have tested the connection between illumination channel 1 and my pH probe attached to my EXB:s internal card. The readings are still confusing. With the channel inactive (no task) or active but the graph says 0 – my pH reading of this probe is 8.2. With the channel active and graph showing ANY number over 0 – my reading drops to 7.8. It means that the channel affect my pH readings in spite if it set to on/off or dimmable.

I have moved my power source for the computer, now it is attached directly to the grid (no UPS). No other readings are affected – I have three more pH probes connected to the system – one of them attached to the internal pH card of another EXB. I.e. the same setup as in EXB number 2

Honestly – I do not understand this behaviour because there is no electrical power involved – only a programming code saying on or off and it only affect one of my EXB. I have other systems with more EXB:s without this problems. Next step is to demount the actual EXB

Sincerely Lasse

[Lasse]

More result from Sweden

I have done a lot of testing today. The connection between my EXB nr 2 and illumination channel 1 consist – whatever I do. With only the EXB connected – it was the same. With the two extra L ports (I have an extension card with two L ports attached to slot 0) taken away – the same problem. I can´t figure this out. Either there is something wrong with my EXB or it is a programming bug – at least - the only explanations I can come up with for the moment.

I moved the pH extension card from slot 2 to slot 3. It looks like it works well just for the moment.

All this has however shown a thing that I think many people forget. There is a need of some grounded devices in the system. Today – when you use a lot of internal pumps and wave makers – there is a risk for a potential build up in the system – your readings of sensitive devices as probes maybe therefore not be so very good if the system not is grounded

Sincerely Lasse

[Lasse]

Update

I log the actual pH measurement during one day. The probe connected to the internal card works rather well but the one connected to the external card (slot 3) have some variations that are hard to explain. The system is newly started, has low load and is not fully cycled yet. Probe 4 is situated directly after the fish tanks and probe 5 is situated in the outlet pipe from a heavy aerated bio filter tank. (no air bubbles around the probe). Its normal with higher pH in the bio filter but the drop at 02:00 in the morning is not possible to explain with real change of the pH. The question is if it could be some fault with the expansion box?

Please see the attached Picture

Screen Shot 05-28-15 at 03.00 PM.jpg

Sincerely Lasse

[Lasse]

Today’s graph - no obvious explanation to the drop of the figures of pH 5. The drop of probe 4 can be explained with help of biological processes. There is no power sources or magnet fields that vary around the equipment.

I need advises - is it wise to start with changing the EXB? - I have new ones that I can test. I have also new expansions cards and new pH –probes. This type of troubleshooting is time consuming and if someone has any idea where to start I should be very grateful.

Sincerely Lasse


Screen Shot 05-29-15 at 09.00 AM.jpg

[Matthias]

In the first post you wrote about a deviation of 0.4 - this is significant and needs to be fixed in case it is really a measuremt problem

but now we are talking about a pH-value swing of 0.06 according to the new graph? I don't think that this is relevant at all

I doubt that there any problems with the hard-or software, I think this mimimal change can't be avoided or excluded at all

[Lasse]

In the first post you wrote about a deviation of 0.4 - this is significant and needs to be fixed in case it is really a measuremt problem

but now we are talking about a pH-value swing of 0.06 according to the new graph? I don't think that this is relevant at all

I doubt that there any problems with the hard-or software, I think this mimimal change can't be avoided or excluded at all

I´m sorry that I´m not good enough to explain my problems - I have had 3 problems with this new system and EXB nr 2.

1) a problem with potential differences (solved)
2) a problem ther ill 1 affects probe 4 (internal card in EXB 2) with app 0.4 in pH (worked arround through not use Ill 1)
3) a problem with probe 5 (extension card in EXB 2) . It now and then changes app 0,4 - 0,5 in pH

My graphs adresses the last problem - number 3. An you can see that it changes with more than 0.4 units if you look att that probes graph. The other (probe 4) that is in the same system (different place) is taken with just to show that it is an indvidual problem at probe 5.

Once Again - there is two graphs in my last picture. One blue (probe 4) - that problem I have fixed if I do not run illumination 1. If I run illumination 1 - it affect even probe 4 but that I have not shown with a graph yet.

The second probe 5 is shown with red. It sometimes without any reason change with 0.5 in pH. Its the red graph and you can surly see how its drop around 02:00 28/5 from app 8,5 to 8 and rise again arround 4 oclock. The same happens arround 7 oclock 29/5 (after this dropp its rised again.

I have worked with pH measurements in biological systems for more than 20 years and I never concerned of changes below 0.1 - 0.2. I´m doing new tests and will come back later on.

I´ll comming back with Pictures of problem nr 2

Sincerely Lasse

Edit: The graphs for probe 4 and 5 shown att my posts 6 and 7 has not the same scale - why I do not know - this graph was automatically done by the ProfiLux programe

[Lasse]

Problem nr 2 - Illumination channel affects probe 4

Look at this Pictures

at 13:03

Screen Shot 05-31-15 at 01.03 PM.jpg


at 13:04 I change Illumination channel to be on between 13 - 14

Screen Shot 05-31-15 at 01.04 PM.jpg

at 13:06 I read this pH

Screen Shot 05-31-15 at 01.06 PM.jpg

at 13:08 I change Illumination channel to off

Screen Shot 05-31-15 at 01.08 PM.jpg

at 13:10 pH back as it was 13;04

Screen Shot 05-31-15 at 01.10 PM.jpg

I have no outlets or other things linked to illumination channel 1 and I do not get this thing to happens wih illumination 2 and 3

Sincerely Lasse

Edit: Probe 5 - not showed above - no changes during this test