2 RAs in tandem + H2O Automation

Talk about you and your tank/equipment
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Joined: Fri Jul 20, 2012 9:42 am
PostPosted: Fri Jan 24, 2014 8:59 am
Hi all,

Getting ready to start the next project and wanted to outline it here, get input and give others some additional ideas. I am planning to get another RA controller to automate my RO/DI and SW mixing stations. It will also run an automatic water change (AWC) system and facilitate filling my ATO reservoir for my main tank controlled by another RA. The main challenge is that the water station is downstairs in my basement while the main tank and sump are upstairs (and on almost opposite corners of the house).

I plan to use the following features for this project

1) Multi-level water sensor (to monitor RO/DI and SW mixing containers)
2) Salinity module (to mix saltwater to proper SG)
3) Float Switch Inputs (to receive signals from the upstairs RA)

The plan is to have a 3 head peristaltic pump that I ordered on ebay. I will currently use 2 heads one to drain water from the main tank and the other head to add new water. Because both pumps are driven by the same motor, the flow rate should be identicial. You can follow the thread on RC that started this all. http://reefcentral.com/forums/showthread.php?t=2349824

I will also employ some 12V solendoids to enable/disable the RO/DI, open/close the bypass to the flow restrictor so I can automate flushing the membrane, and to direct water to either the SW bin or ATO reservoir upstairs.

The biggest challenge aside from running all the tubing (currently planning on up and over through the attic) will be having the two RA units talk to each other. I am currently planning to run a Cat-5 cable to carry the signal. I will use two pairs which will connect to the ATO High and ATO Low ports on the downstairs RA. The High ATO switch will be controlled by an outlet connected to a relay, like I do with the auto-feeder.

I will use the WL sensor in my ATO reservoir to determine when to open/close this circuit. The downstairs RA would see the circuit close and start filling the reservoir upstairs. I would let the water pressure from the RO/DI feed the system, rather than drive another pump. It should take less than 20 minutes to refill the container (less than 5g with a 75gpd RO/DI). I'll use the solenoids to flush the membrane first for a minute and then fill the container.

The ATO low will be a signal to enable/disable the AWC system. I plan on connecting these in parallel with my current float switches for high and low sump level. If either of those float switches are triggered then the AWC would be disabled. I'm not sure if that would cause any problems having two RAs share the same float switches. If anyone sees an issue with this, LMK.

For salt water mixing. I'm not "currently" looking to automate adding salt or build a complex hopper. I currently use a 20g Brute for mixing SW. I would look to add water to the 85% mark and then add enough salt to get 35ppt salinity when it's at then 90-95% level. I'll then let the salinity module drive the filling of that container until its at the right dilution. This would ensure that I'm always adding the right water salinity to the tank upstairs.

Anyway, I hope these ideas are useful for someone and would love some feedback. This is going to be a slow project as I have a lot of components to get and this isn't of the highest priority, but at least its a plan. Feel free to discuss similar setups, this thread doesn't need to be dedicated to mine :) Would love to see what others might do too.
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Location: Davie, FL
PostPosted: Fri Jan 24, 2014 9:25 am
Thanks Lee.

You and I are looking at doing a lot of the same things.
I'm looking forward to seeing if and how the 2 RA's will talk to each other.

My first project is to build a new stand and move the tank before I get into all this, but I have the dual head peristaltic pump already and I ordered some solenoids today from this guy on E-bay that has a good selection at decent prices.

http://www.ebay.com/itm/1-4-Inch-Plasti ... RTM1562570

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Joined: Fri Mar 18, 2011 6:47 pm
PostPosted: Fri Jan 24, 2014 9:27 am
1 float 2 RAs doesn't sound like a good idea.
Ground sharing that long of a distance is not recommended.
Roberto.
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PostPosted: Fri Jan 24, 2014 9:47 am
Roberto,

Would it be any different using an IO module? or the outlet control triggering a relay to close the circuit? Just trying to figure out the best alternatives. What would be the drawback to the ground sharing? Forgive my ignorant electronics knowledge.

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Joined: Fri Mar 18, 2011 6:47 pm
PostPosted: Fri Jan 24, 2014 10:15 am
If you share grounds over long distance, you are prone to ground loop and there is also a possibility to pick up noise over the length of the cable.
The best would be to isolate the signal with opto isolators.
Your idea of the relay would work well too. They would be a mechanical isolation instead of optical.
Just make sure the relay is on the receiving RA side and not the on sender. In other words, place the relay close to the ATO port and not close to the power supply plugged into the relay box.
Roberto.
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PostPosted: Fri Jan 24, 2014 10:53 am
Gotcha, so I'd send a 5v/12v dc signal over the cat5 and have the relay near the remote RA. I could use the opto isolators. I'd like to not use more outlets if possible. Can you explain that a bit more? Would I be doing the same thing with that and keep the isolator close to the remote RA?

Also would it be possible to send the signal from the lowATO pins if I wanted to "simulate" the float switch being activated?

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PostPosted: Fri Jan 24, 2014 11:05 am
Like this:
opto.png
opto.png (2.57 KiB) Viewed 3491 times


You can also use the ATO ports or dimming ports too, but if it is very far, I'd go with a power supply.
Otherwise you would be having to use one opto in each end.
Roberto.
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PostPosted: Fri Jan 24, 2014 11:19 am
So that's coming from the float switches connected to the RA upstairs to the ATO port on the RA downstairs?

Is another power supply required on the upstairs end? or is the one on the left the RA power?

Is the 5V power supply always on? Is that just for supplying power to the optocoupler? or is that power also coming from the RA?

The run is going to be approximately 100' give or take some. I may just go with the mechanical as that would give me actual control from the RA rather than just rely on the float switch status.

Would there be any better way to communicate between two RAs over that distance? Maybe I could simulate i2c or something over the cat-5 instead. Just thinking long term...

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PostPosted: Fri Jan 24, 2014 11:28 am
That's too long for I2C.
I thought you were going to use a relay port.
Connect the power supply to the relay port and use the current float that is already connected to RA upstairs.
If you want a total independent solution, wire up another float switch in series with a power supply (connected to the wall outlet) and send the wires downstairs to the optocoupler.
The +5VDC can be wired from the temp sensor connector.
This is the disadvantages of using the optocoupler. You need to power them.
If you go with the relay, you don't need the +5 and can wire the contacts from the relay straight into the ATO port.
The other alternative is an XBEE or RF link, which are wireless solution.
Roberto.
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PostPosted: Fri Jan 24, 2014 11:43 am
I was going to use a relay port for the ATO reservoir since I will base that on the WL sensor.

For activate/de-activate the AWC, I was going to let the state of my current float switches be the indicator. Currently the high and low float switch are wired in parallel to the upstairs RA on the LowATO port. So either switch activates, the LowATO port goes on and I disable my Return+Skimmer.

If I'm understanding correctly, which I'm not sure that I am... I could run another paralell connection from the float switches to the optocoupler which would then connect to the second RA ATO port and the Optocoupler could get power from the temperature sensor?
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