Using industrial controllers for a marine aquarium

15 May 2007
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Hi everyone,

Being the way I am, I get VERY frustrated when I'm forced to pay much more for an item than what I know it's worth, and in our hobby this is usually the case when one visits a petshop/LFS.

Like most serious hobbyists, I've had the need to monitor the most important tank parameters electronically, and to capture the data on my computer for further analyses and record keeping - I've just never been happy to pay upwards of R10 000.00 for a hobby-grade "tank computer".

Well, I've recently found a solution - use industrial-grade controllers, available locally , and even cheaper than the flimsy hobby-grade "computers"... in fact, use the VERY SAME controllers used by some of our public aquaria. These controllers not only monitor the required parameters, they can also control them by switching relays. They are much more rugged, can be mounted up to 1.4km away from the tank, can be bought in 230V AC or 24V DC configuration, can be programmed to trip alarms, and can send the data to your computer using the industrial standard RS485 protocol, where it is recorded in Microsoft Excel or ASCII text format by the software supplied free with each unit. The units are daisy-chained from one to the next, and the connection to the PC is with a simple UTP network cable.

Here is a photo of my current 3-controller setup, consisting of a pH, temperature and ORP controller - I will be adding a conductivity controller at a later stage.


One of the nice things about these controllers is that they are completely modular - by simply changing some software settings (and the probe, of course...) one can change the unit from a pH controller to a temperature-, ORP-, or conductivity controller, and if something packs up, one simply replaces the broken module, power supply, etc. and NOT the entire "computer". Also, should something be damaged, it will not affect the other controllers.

While I was busy installing these controllers, I also decided to tidy up my light controllers (also rugged industrial units, as can be seen at the bottom of the following photo), and to install them and the temperature controller's relays in an IP65 rated waterproof switch box.


To me, one of the nicest "features" of using these controllers is the fact that I can generate a graphical picture of the tank parameters. As can be seen from the following Excel graph, the controllers also allow for a MUCH more precise control on variables, such as temperature. The first few days show the tank temperature swing before the controller was activated (only using it as a measuring instrument during that time...). At the time, the tank was heated by 3 Jaeger heaters, totalling 700W, and cooled by a Hailea 500 chiller. The data recorded during the next two weeks showed clearly that the overnight temperature drop was still a bit low, and this prompted me to add a fourth Jaeger heater (of 200W), effectively reducing the temperature swing by 0.4 degrees.

Last weekend I made a small adjustment to the controller's parameters, and the results of the past week clearly show a further 0.3 degree reduction in the maximum temperature swing (this time improving the control of the chiller...).

So, by simply adding the controller and one additional heater, I've reduced the tank's temperature swing from about 2.4 degrees (25.3 - 27.7) to only 0.8 degrees (25.6 - 26.4)


I have not yet started "playing" with the pH and ORP controllers, but hope to achieve similar improvements on these parameter swings during the next few months...

Hi Hennie

Most impressive, noe here starts the questions:

What equipment is this?

Who is the supplier

How much?

On the verge of setting up and been looking at variuos Process systems from AC/DC and RS components.

Please help

Carl dad is a manager at beecan nampak.and i asked him about these controllers.he said that he will try n get me one as soon as they do an upgrade of consists of most water parameter checks,he did say its a simple touch screen,with a controller and a whole lot of probes going into the actual machinery.ive been nagging him to bring one home to see if i can connect it up.i know that theres ph,redox,temp and couple other stuff all built in
This thread is useless without prices. :lol:
Very nice, i have been using an industrial temp controller for a few yrs now and works very well.
Great thread Hennie. What software comes with the controller and what 485 to 232 interface do you use?
Go mad Hennie :) Freedom of speech and all that :p

We'll sort it out if anything doesn't comply, don't worry.
Hi Hennie

Check this forum at reef Central on reef automation.

This forum is about building and programming "control systems" from scratch. Unfortunately for me, I don't have the knowledge or the time to do that (I would love to be able to, though...), and that's why I chose to buy commercially available equipment instead.

"Building" my system only involved wiring the units and power supplies together, and boxing them in the display case - this took about 3 hours of my time. I then had to struggle for another few hours trying to make sense of the Taiwanese:English translated operating instructions (NOT very good, to say the least...), but I did eventually figure out what they tried to say.

Great thread Hennie. What software comes with the controller

Thank's Tom.

The software is an in-house program supplied by the manufacturers of the controllers. If there is one thing I'm not totally happy with, it's this software. It's not very professional, and lacs a few functions, but it IS doing what it was intended to do - recording the information.

The controllers are individually programmable themselves, or one can program them via the computer program. The software can monitor/control 3 x 10 controllers, and one could conceivably monitor & control 30 controllers on one tank, or 10 controllers on 3 tanks.

what 485 to 232 interface do you use?

I'm using a very nifty little USB interface, called "Adam". It can accept RS232 or RS485 input, and connect to any USB port - It can only communicate with COM 1 & 2 though, so I needed to re-configure the port settings in Windows' Device Manager to make COM 2 available for this interface.


Go mad Hennie
Thank's Viper. I'll still keep the dealer's details to myself - If anyone should be interested they can PM me, and I'll let them have the info.

Being modular, one does have a certain amount of leeway in what to use for e.g. housing, power supplies, even probes, so these prices could vary :whistling: The actual controllers also vary in price by the number of functions required, and the size of the controllers, so I will "quote" on what I bought, and then elaborate a bit...

Basic 1/16 DIN (48mm x 48mm) AC-mains powered controller with 2 relays, 1 alarm output, RS485 communication interface and PC software: R1 251.72 each (including VAT)

The same units, but without the control outputs and communication interface (in other words, just a measuring instrument) would be around R880.00 each.

The prices of the probes vary considerably, depending on make, TYPE, and configuration. I believe that industrial pH and ORP probes are much more rugged, and last MUCH longer, than the thin glass or plastic bodied "scientific" probes normally available. Unfortunately, they are also more expensive (but worth it, IMHO). One can, of course, use the "hobby" grade probes if one needs to reduce the initial cost. Using industrial 4-20mA transmitter type probes, one would, however, save money on the long run, as one would not need to replace the transmitters, power supplies, etc. when the probes reach the end of their lives.

I opted for the following:

pH probe: 3/4" diameter (20mm), double junction, ceramic combination electrode: R1098.00 + nylon head, 4-20mA transmitter and power supply: R859.00

ORP probe: 3/4" diameter gold plated flat surface electrode: R1 262.00 + nylon head, 4-20mA transmitter and power supply: R859.00

Temperature probe: Pt100 Hastaloy coated RTD, with nylon head: R360.00

Total cost came to R8 191.00

Hope that's enough info :svengo:

NOG! Gooi daai info ;) Thanks Hennie can you show a pic of these beasties... um from a distance? Thats the probes, and whole controller group. Is the software "open source" ie can we tune it?
Hennie can you show a pic of these beasties... um from a distance? Thats the probes, and whole controller group. Is the software "open source" ie can we tune it?

OK, the whole controller group, mounted in the display cabinet:


Unfortunately I cannot show everything together, as all the probes are installed in the tank, and I'm NOT going to undo their wiring at this stage....

Here's a screen dump of the software main screen:


As one can see, only the first three controllers are active.

The software is not open sourced, but due to the controllers using industry standard Modbus configuration they should be able to work on other control programs as well - in fact, I'm currently looking to find other software to try...

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