Using Thrusters as wave makers in aquariums

[Reef-Engineer]

I guess where I would start:
1. Remove and disassemble thruster, check out whether some sand or something bad got into the motor assembly.

2. On your arduino, set up serial output so that you can see the PWM signal being sent out in real time. This will tell you whether the arduino is still trying to run the thruster, but the thruster is stopped.

If the arduino is not sending out a good PWM signal (something between 1550-1900 ms) then the issue is in the program or arduino.

If the arduino is sending out a good PWM signal but the thruster is not running, and you checked out your thruster hardware already then the issue is in the power infrastructure (power supply, ESC). You could troubleshoot that by looking at the current draw of the power supply to see if it seems right, check signal coming to and from the ESC to the motor.

Totally possible that the code might be allowing the system to get into a stopped state and not out of it. Weird that it would take so long to expose itself, but definitely possible. The serial output view will show that. To do it just plug into your arduino with a USB cable and your computer and run the program with the serial output window open and check it out.

Good luck!

 

[ravi197699]

I guess where I would start:
1. Remove and disassemble thruster, check out whether some sand or something bad got into the motor assembly.

2. On your arduino, set up serial output so that you can see the PWM signal being sent out in real time. This will tell you whether the arduino is still trying to run the thruster, but the thruster is stopped.

If the arduino is not sending out a good PWM signal (something between 1550-1900 ms) then the issue is in the program or arduino.

If the arduino is sending out a good PWM signal but the thruster is not running, and you checked out your thruster hardware already then the issue is in the power infrastructure (power supply, ESC). You could troubleshoot that by looking at the current draw of the power supply to see if it seems right, check signal coming to and from the ESC to the motor.

Totally possible that the code might be allowing the system to get into a stopped state and not out of it. Weird that it would take so long to expose itself, but definitely possible. The serial output view will show that. To do it just plug into your arduino with a USB cable and your computer and run the program with the serial output window open and check it out.

Good luck!

I agree with statement above, it will be either arduino, code or something stuck in thrusters,

 

[ravi197699]

It does the initialization sound when I turn it on, then it just stops running a few minutes later with no beeps.

any updates with diagnoses?

 

[Reef-Engineer]

@sawdonkey did you get sorted out?

I am just about ready to start running mine on the tank instead of the rock tub.

I will disassemble when i move it over to evaluate 2-3 months of wear and let folks know what I find.

Then in another month or so I’ll make the call whether to get a 2nd T200 for the display tank or go another route.

 

[ravi197699]

@sawdonkey did you get sorted out?

I am just about ready to start running mine on the tank instead of the rock tub.

I will disassemble when i move it over to evaluate 2-3 months of wear and let folks know what I find.

Then in another month or so I’ll make the call whether to get a 2nd T200 for the display tank or go another route.

my thrusters (t200 and t500) has been running for close to 12 months and so far so good, I am trying to figure out way to have thrusters installed on similar to sea swirl so I can use 1 thruster that will turn 180 deg to provide flow,

 

[Reef-Engineer]

I saw someone do that on a vid. It just needs to be a very stout support to handle the long moment arm.

My next idea is a wide funnel output. Think like the housing i have now but the output turns 90 degrees and flattens out to a 1 foot wide 1” tall blade. Think the end of your vacuum cleaner. Use the thruster to push water out and the nozzle creates wide smooth flow.

The floe produced would be like a gyre but much stronger. Id mount it to the back wall and have it push a ton of flow forward over the reef

I need to model it up.

 

[ravi197699]

I saw someone do that on a vid. It just needs to be a very stout support to handle the long moment arm.

My next idea is a wide funnel output. Think like the housing i have now but the output turns 90 degrees and flattens out to a 1 foot wide 1” tall blade. Think the end of your vacuum cleaner. Use the thruster to push water out and the nozzle creates wide smooth flow.

The floe produced would be like a gyre but much stronger. Id mount it to the back wall and have it push a ton of flow forward over the reef

I need to model it up.

That will be great, please share your findings,

 

[ravi197699]

I saw someone do that on a vid. It just needs to be a very stout support to handle the long moment arm.

My next idea is a wide funnel output. Think like the housing i have now but the output turns 90 degrees and flattens out to a 1 foot wide 1” tall blade. Think the end of your vacuum cleaner. Use the thruster to push water out and the nozzle creates wide smooth flow.

The floe produced would be like a gyre but much stronger. Id mount it to the back wall and have it push a ton of flow forward over the reef

I need to model it up.

I found servo motor device that moves left to right and it should be able to live the thrusters 180 deg just need to secure the bracket that is strong enough so that it does not move when thrusters are on, they are very strong when they push water, I will try to build this month after I return from trip

 

[Biff0rz]

Very interested in this project, hoping for the best diagnosis. I'd check for something overheating or over-volting.

 

[Reef-Engineer]

Ok, I took down the rock tub, and put up the tank. It has been a looong operation, but this isn't about my build, it is about the T200 thruster from Blue Robotics.

Blue Robotics mentions that all metals on the T200 are 316 SS and as such should be very robust to corrosion, but unfortunately I have to report that my thruster had significant corrosion issues in the 3 months it was in use, leading me to likely not re-deploy it in the new aquarium.

Some pictures:
Here is the thruster, dirty, but functional after roughly 3 months of use.

Now with the housing (functioning as nosecone) off:

More of the bushing that holds the rotor in place:

My housing and magnets did well, no corrosion on the magnets and the housing never cracked:

But even the threaded inserts of the thruster seemed to suffer corrosion:

Not sure how many photos I can do in one post so I will continue in next post.

 

[Reef-Engineer]

Here is the rotor, you can see some uneven wear, but overall the epoxy coating did pretty well:

Beyond the corrosion and wear, I noticed that the shaft of my thruster has a big bend in it. Like more than 0.5mm over 5mm length. It shows itself at the nosecone area and no wonder this thing was noisy with that vibration at high rpm. It is a wonder it worked as well as it did. I will reach out to blue robotics and let you know what they say, I never disassembled it before, so I did not damage it, and no amount of operation is going to bend that shaft that much, so it was like that from the factory. Definitely unsat. In these three shots the housing is in the same position and I am just rotating the rotor with my finger. It is easy to see that as it rotates the *less* rusty side is almost contacting the housing and the rusty side has a bunch of clearance. This would result in significant imbalance since the shaft and that bushing are a good percent of the rotating mass.

So where to go from here... not sure. I could remove all inserts not in use by heating them up and pulling them out. I could get Blue Robotics to send replacement parts for some of the really corroded bits (if they will) but I am mostly worried about unknown status of the rotor coating and potential to leach contaminants from the magnet or any of the corroding metal.

If you are running one of these, please take it apart and have a look. I must say, I am bummed about this but hey I had fun playing with it and learned a few things. I'll let you all know what Blue Robotics says.

 

[ravi197699]

Here is the rotor, you can see some uneven wear, but overall the epoxy coating did pretty well:

Beyond the corrosion and wear, I noticed that the shaft of my thruster has a big bend in it. Like more than 0.5mm over 5mm length. It shows itself at the nosecone area and no wonder this thing was noisy with that vibration at high rpm. It is a wonder it worked as well as it did. I will reach out to blue robotics and let you know what they say, I never disassembled it before, so I did not damage it, and no amount of operation is going to bend that shaft that much, so it was like that from the factory. Definitely unsat. In these three shots the housing is in the same position and I am just rotating the rotor with my finger. It is easy to see that as it rotates the *less* rusty side is almost contacting the housing and the rusty side has a bunch of clearance. This would result in significant imbalance since the shaft and that bushing are a good percent of the rotating mass.

So where to go from here... not sure. I could remove all inserts not in use by heating them up and pulling them out. I could get Blue Robotics to send replacement parts for some of the really corroded bits (if they will) but I am mostly worried about unknown status of the rotor coating and potential to leach contaminants from the magnet or any of the corroding metal.

If you are running one of these, please take it apart and have a look. I must say, I am bummed about this but hey I had fun playing with it and learned a few things. I'll let you all know what Blue Robotics says.

Thank you for sharing, I cleaned my thrusters, and I did not notice any rust and everything is moving freely, did you reach out to Blue Robotics in regards to this?

 

[Reef-Engineer]

Thank you for sharing, I cleaned my thrusters, and I did not notice any rust and everything is moving freely, did you reach out to Blue Robotics in regards to this?

Yes, I sent them pictures of the corrosion and bent shaft. I will let you all know what they say.

 

[ravi197699]

Thank you for sharing, I cleaned my thrusters, and I did not notice any rust and everything is moving freely, did you reach out to Blue Robotics in regards to this?

Top mounting holes are sealed with epoxy so there is not run on the back, I wonder if 2 part clear epoxy will seal the back side to prevent rust,

 

[ravi197699]

Yes, I sent them pictures of the corrosion and bent shaft. I will let you all know what they say.

let's see what they have to say about this?

 

[Reef-Engineer]

Blue Robotics got back to me and said that the 316SS that was in use must not be of sufficient grade to allow for prolonged use in the marine environment (inclusions leading to pitting and excessive corrosion). They said they thought the bent shaft might be due to a failed bearing, but I think the motor just uses bushings, so I am not sure what that was about. They kindly refunded me for my thruster.

Unless I try one of the other brand thrusters (more $ unfortunately), this might be the end of my thruster journey. If that is the case I would be happy to send my existing housings to Ravi or Sawdonkey, though I might want a few bucks for the one with $80 of magnets in it.

 

[DanyL]

That’s unfortunate

I don’t have a tank long enough (only 1.8m) to justify thrusters as strong as the T200, but I watched this thread closely, because it’s definitely an interesting approach.

I wonder if the 316 stainless steel parts used in Ravi’s thruster compared to yours were sourced from different suppliers, or maybe same part supplier but different alloy supplier.

I don’t know if there are any other environment variables that could influence the rate of corrosion - maybe PH?

 

[ravi197699]

Blue Robotics got back to me and said that the 316SS that was in use must not be of sufficient grade to allow for prolonged use in the marine environment (inclusions leading to pitting and excessive corrosion). They said they thought the bent shaft might be due to a failed bearing, but I think the motor just uses bushings, so I am not sure what that was about. They kindly refunded me for my thruster.

Unless I try one of the other brand thrusters (more $ unfortunately), this might be the end of my thruster journey. If that is the case I would be happy to send my existing housings to Ravi or Sawdonkey, though I might want a few bucks for the one with $80 of magnets in it.

what about thrusters that are oil filled and very minimum contact with saltwater, I think that is was being used by Abyzz pumps

 

[Reef-Engineer]

Id love to take apart an abyzz thruster to see what they are using. But that is an expensive experiment.

@DanyL i think you are likely right that the difference between ravi’s thrusters and mine are material batch to batch quality.

 

[ravi197699]

Id love to take apart an abyzz thruster to see what they are using. But that is an expensive experiment.

@DanyL i think you are likely right that the difference between ravi’s thrusters and mine are material batch to batch quality.

this is possible, here is what I found so far but I will search more, I know for sure that options are available,

TDS8 Metal Underwater Thruster ROV thrust 7.0kg 25.2V 350W Pressure re

Design parameters: 1. Product model: TDS-8 2. Sealing type: Maintainable fully sealed 3. Sealing structure: adaptive rotating dynamic sealing structure 4. Pressure compensation: positive pressure oil pressure compensation 5. Shell material: 6061 aluminum alloy hard oxidation 6. Material of air...

www.hobbywater.com