Discussion in 'Do It Yourself (DIY)' started by DBR_Reef, Nov 6, 2017.

Automatic Frozen/refrigerated food dispenser

I wanted a way to automate feeding of diverse and healthy foods to both corals and fish. Dried coral food and pellet food in an automatic fish...
  1. DBR_Reef

    DBR_Reef Well-Known Member Article Contributor

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    Automatic DIY refrigerated food dispenser



    Hey guys, so I’ve been working on this one for about a year now, and I’m very excited about finally getting this out to you. I wanted a way to automate feeding of diverse and healthy foods to both corals and fish. Dried coral food and pellet food in an automatic fish feeder are decent options, but picky fish tend not to get fed, smaller foods are hard to accurately dispense, and the variety of the food is lacking. There have been successful attempts at frozen food dispensers, but they are too complex for my taste. So I made a refrigerated food feeder. The hardest part of this by far was getting the preservation of food done properly. This first video is going to cover the mechanical components, and in the next I will do the food. What I ended up building is similar to other designs, but is different in a couple of important ways.

    I produced my version for under $50 with easily found parts, while the best other version I have seen by Aquabacs cost him $450 without the fridge. The most notable design difference between this and other designs is a peristaltic pump that has 6.8mm ID tubing instead of 1.67mm tubing, increasing the size of deliverable food.

    The three problems we need to tackle are keeping the food cold and fresh, keeping the food suspended, and delivering the food.

    Keeping food cold and fresh:

    Keeping the food cold is of vital importance, as this is one of the best preventers of food degradation. It is really important that the food be as close to freezing (without freezing) as possible. For this reason most Peltier based refrigerators will not work. I used a really old mini fridge I had laying around, and after the world’s most disgusting cleaning and replacing the door panel with a frp panel to get extra room, it was good to go. However I have this setup in the basement, where noise from a refrigerator compressor is not a concern- If that is a problem I recommend an absorption refrigerator. These are the type generally used in hotels because they are nearly silent but are still energy efficient and capable of freezing.

    Keeping food suspended:

    Option 1: a stir plate. I used a laboratory stir plate that I had. If you search for a diy stir plate, you should be able to find something that will work for a low cost. They also sell ones on ebay for $40 if you don’t feel you have the skills or want something more polished.

    Option 2: an airline to the bottom of the storage container, without any air stone- the airpump should be placed in the refrigerator. This will probably result in faster oxidation of the food than a stir plate and a poorer stir.

    Option 3: Sodium Alginate- what commercial products use, you’ll have to do your own research on this. My guess is that this will still need occasional shaking.

    Automatic feeder:

    The feeder works by taking water pumped from the sump/tank, and passing it through a tee fitting located just outside the refrigerator. Into the feed side of the tee, a large volume dosing pump dispenses the food.


    To build the feeder you need:

    1. Feed line from a dedicated pump or from a manifold off the main return pump (I made mine ½ inch). There are also a couple designs running around that use a DOS to back flush the line with tank water and skip the feed line. This design has some clear flaws, most notably the contamination of the food with tank water, and while the diameter of dos tubing is thicker at 3.33mm, that is not even close to 6.8mm. Hypothetically, one could run two power supplies to the larger peristaltic pump to back flush it just like a dos, but it really is a poor solution.

    2. A tee and three barbed fittings. I would not recommend a venturi injector like this (which I initially tried), the ports are just too small and easily clogged, and gives you a false sense of security- it won’t do anything in case of lost power or a blockage. These can all be found at your local home improvement store.

    3. A few feet of silicon tubing ($5) (http://www.ebay.com/itm/1-4-ID-x-3-...ible-Tubing-High-Temp-Hose-500F-/271334471955)

    4. A high flow peristaltic pump- this is a cheap knock-off of a masterflex- you could buy a masterflex, but they are not always available or cheap. I used it over a masterflex because it was more compact, which was important in a minifridge. ($30) (http://www.ebay.com/itm/12V-Large-F...m-Aquarium-Lab-Analytical-Water-/401222703897)

    5. A way of controlling the peristaltic pump. A digital timer ($13)(https://www.amazon.com/WenTop-Programmable-Energy-saving-Household-Appliances/dp/B010AH61G4) or a reef controller

    6. A food safe container that is air tight. I found one at Walmart. This is one of the safeguards we are building into the system to prevent flooding. If this feeder is going to be in living spaces I recommend having the food storage above the sump water level.

    7. Your mixing method

    8. Your refrigerator

    First, we need to prep the refrigerator. We need to cut holes in the fridge for the power to the peristaltic pump and stir plate, as well as the silicon tubing. Position everything in the fridge and then drill the holes. Drilling through a fridge can be risky- there can be coolant lines or wires that could be severed. I recommend drilling very carefully just through the plastic inner sheathing, then removing insulation by hand, then drilling through the outer sheathing.

    Then take your air tight container and drill a hole slightly smaller than the silicon tubing, so that when inserted it seals itself. Then take apart the peristaltic pump head, and replace the short piece provided with the full length of silicon tubing. This reduces the number of failure points and places that catch food particles by 2. Then insert the feed hose into the food container, plug in the pump and stir plate, attach the silicon hose to the tee, attach the too and from lines to the tee, position the outlet where desired, and program the timer to turn on the peristaltic for the required time. I decided I wanted 20ml of food slurry pumped 4 times daily (I have a heavily stocked 180 with frag tank and was replacing all other feedings). So, I took a smaller container with 80ml of slurry and timed how long the system took to empty the container, then divide by 4 to get the number of seconds to turn the pump on for. That’s it! I think this system has the potential to greatly increase coral and fish growth and health, and allow those of us this busy lives to keep some of the organisms we have previously had to avoid. I know personally this has allowed me to keep non-photosynthetic gorgonians and a copperband butterfly, ans well as healthier corals.

    The food:



    Making your own food means not using premade food by reefnutrition or others (which is a great product, but is an expensive product- apparently up to $70 per bottle). I have been using this homemade, automatically dosed food for over a year. Any frozen food or DIY fish food recipe will work, I based mine off of this one (http://www.melevsreef.com/node/1616) and included Mysis, baby shrimp, pellet food, nori, scallops, mussels, Cyclop-Eeze, spirulina, silversides, reef chili, and anything else I could find that looked good. Your local Asian grocery store is your friend here. The one food I do not recommend is squid and octopus—not only are my fish not really a fan, but it is harder to grind into uniform sizes and it tends to somehow congeal when stirred into these balls of squid tissue that are really tough and block the pump intake. Just avoid them, they are a serious pain. Initially I blended the larger ingredients in a food processor, and tried to strained it through a mesh to remove and reprocess anything larger than ~1/8 inch- this worked but not well. If you have a meat grinder I highly recommend it. Any grinder will do- seafood is not hard to grind like pork- even a hand grinder will do. Otherwise you tend to end up with large chunks of certain foods and obliteration of other foods. I guess if you just meant to feed coral you could just puree it. I used a fine grinding plate and let the food just start to thaw- about 30 min in cool water before grinding. Cooling your grinder in the freezer is also helpful. I then add mysis, shrimp and other smaller ingredients that did not need to be reduced in size. I freeze this into blocks that last me about 2 weeks. A few months of food takes me about half an hour to make and can cost under $10- I always end up adding in more expensive ingredients though. One should keep in mind the nitrate/phosphate balance when using any homemade food. I tend to have a lot of herbivores in my tank, and to keep them healthy I use a lot of phosphate rich foods (ie seaweed). Generic shrimp also have more phosphate than Mysis shrimp. The list goes on, but if you already have a nitrate deprived system, this kind of feeding can quickly push you into running a lot of GFO or finally breaking down and starting to dose nitrates, which is what I am going to start doing.

    Keeping food fresh:

    This is the most important step- unpreserved fish food will go bad in far less than a week, depending on starting ingredients and temperature. The preservatives here were carefully chosen with the help of several university faculty with degrees in food science, but this was a little out of even their wheel house, so they are high but safe usage dosages. This recipe is just a baseline, but I have tested this version and had an edible product for 3 months, although I suspect some of the nutritional value was lost by that point. The largest additives, citric acid and ascorbic acid are both used in reef tanks for other reasons in quantities much higher than we are talking here. Calcium proprionate and sorbic acid are used in other commercial aquarium foods, and I have not had any negative effects, although I am not sure what I would even look for. Even so, these are mold, yeast, and fungi inhibitors, and not completely needed unless you want to keep food for a month or more. I have actually cut my additions in half, and may reduce them further, as my container size means I have to make new food every 2 weeks. If you would like to understand better why we are using what we are using, I can point to towards some resources, just ask.

    Citric acid (to acidify-- most bacteria we are worried about do not reproduce under a pH of 4.5-- and as an antioxidant): .5% by weight

    Ascorbic acid (vitamine C, for stability): .5% I use pills and grind them because it is cheap and easy to measure.

    Calcium Proprionate (Mold inhibiter): .1% (may want to cut this in half or more)

    Sorbic Acid (mold, yeast, fungi): .1% (may want to cut thins in half or more)



    One important caveat - it is super easy to overfeed with this system, and while this food is not as nutrient dense as straight flake or pellet food, it can quickly overwhelm a tank. This is of extra concern because one of the main reasons one might implement this system is to care for corals or fish that need multiple feedings per day to thrive (like non-photosynthetic corals, fish fry, or picky fish- I wanted both a copperband and non-photosynthetic gorgonians). As such, I highly suggest an effective particulate nutrient export method. This kind of system more closely reproduces the reef environments we are replicating, with a high turnover environment. Good flow within the tank with no dead spots, so that particulates stay suspended, as well as some sort of mechanical filtration to remove particulates before they break down are important. A rollermat, a diy rollermat (http://www.reefcentral.com/forums/showthread.php?t=2552341), or the new dream boxes (http://www.reefcentral.com/forums/showthread.php?t=2614456) would be excellent, low maintenance choices. I have also found I have to blow off rocks far more frequently, but these are general problems associated with broadcast feeding.
     
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  2. mdbannister

    mdbannister Ahh...the Reef Life Staff Member Team R2R R2R Excellence Award SCMAS Member Build Thread Contributor Article Contributor Partner Member 2018

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    Great job on the videos and write up! Very cool innovation! Thanks for sharing!
     
  3. ecdrgonz

    ecdrgonz Active Member R2R Supporter

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    Very interesting
     
  4. revhtree

    revhtree Owner Administrator Staff Member Team R2R R2R Supporter R2R Excellence Award Photo of the Month Award Build Thread Contributor Article Contributor Partner Member 2018

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    Awesome video and thread!
     
  5. Mrx7899

    Mrx7899 Well-Known Member

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    Very cool
     
  6. cilyjr

    cilyjr Well-Known Member

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    @DBR_Reef Do you worry about a leak from a possible tubing breakdown in the peristaltic pump head?

    How does the pump like the back pressure from the manifold pump? As you've been using it for a while I assume it's a non issue.

    Is that pump noisy? And if I wanted to think I could use this to control the speed?
     
  7. cilyjr

    cilyjr Well-Known Member

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    Nicely done build though. Kudos
     
  8. DBR_Reef

    DBR_Reef Well-Known Member Article Contributor

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    The tubing is a thicker walled silicon than is on most peristaltic pumps, so I'm not worried about it, but it is on my bi-annual check/replace list.
    Peristaltic pumps do pretty well with head pressure, so the back pressure has not been a problem.
    The pump is not any noisier than any other peristaltic pump I have used.
    I don't see any reason to control the pump speed, it seems easier to control time. I would also not use it because I believe they change voltage, which I think reduces torque (don't quote me on any of that) on a already small motor. Thank you for the link though- I use those all the time and usually order them from china- that one even comes with the double throw switch.
     
  9. cilyjr

    cilyjr Well-Known Member

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    Np. I'm also thinking of using that pump for another reason and speed control would be a requirement for that. That peristaltic pump looks like a much higher quality than the even cheaper plastic ones that Amazon has.
     
  10. ihavecrabs

    ihavecrabs Well-Known Member Build Thread Contributor Article Contributor Partner Member 2018

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    How have you found the negative pressure build up in the food storage container?

    I take it if it is air tight and you are pulling from it with the peristaltic pump, it is causing some kind of vacuum or minimizing the effectiveness of the peristaltic pump.

    I was thinking one could run a small airline tube to over the sump or tank area so that if there was a failure and the main pump was pushing water back into the container, it would go through and then back into the tank.

    Thoughts?

    Awesome job on the video and write up. I'm highly considering this for my build!
     
  11. cilyjr

    cilyjr Well-Known Member

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    Or just add a backflow preventer that would allow air to be sucked in but stop water from pushing out
     
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  12. DBR_Reef

    DBR_Reef Well-Known Member Article Contributor

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    Yeah, the complete airtight container could actually be a problem. I did think about this, but with the small about of food taken out each time, I don't think it will be a problem for most people. My "airtight" container is not very air tight, and will actually leak a small amount of water over time (I tested it), which evaporates and freezes on the coil. I figured if people shoot for airtight they will get watertight, hopefully. If you can get a true airtight container then I think a vent line would be a great idea. Ideally the food reservoir would also be above the sump, but I know that is not practical for many set ups.
     
  13. DBR_Reef

    DBR_Reef Well-Known Member Article Contributor

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    yeah, kind-of like a skimmate locker. ping pong in a tube sort of thing
     
  14. Abhishek

    Abhishek Well-Known Member

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    Amazing and thank you so much for the amazing work . I have been slowly looking to build one for my future NPS tank and this has helped me a lot .
    Could you provide a link for the most suitable refrigerator you think for this purpose ?

    I have a Hanna Instruments HI 190M Magnetic Stirrer that I got off ebay . What do you think about this ? Will this work ?

    https://hannainst.com/hi190m-1-magn...RC3m2kHU5t8s9xrXQSOwdtLVPFmNAf3BoCBHoQAvD_BwE

    Regards,
    Abhishek
     
  15. DBR_Reef

    DBR_Reef Well-Known Member Article Contributor

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    Fridge choice is highly dependent on your needs- does it need to be: quite, store your extra frozen food to get it out of the family freezer, small enough to fit under a stand, or large enough to hold your extra beer :) But maybe something like this if you want very quite- https://www.amazon.com/Generic-Absorption-Electric-Refrigerator-Fidge,36/dp/B071XXL7CD/ otherwise I would just get whatever is cheapest on craigslist or at walmart

    I would think that that stirrer would work perfectly, but I don't know much about stirrer plates. I have found that some older ones that I find for free (probably 30-40 yrs old) sometimes have very week magnets that do not transmit the torque well. If you do have a problem with the stir plate not being able to stir the food then I would try either a stronger magnet stir bar, a smaller stir bar (less resistance), or a glass container (which reduces friction on the stir bar).
     
  16. brian.brigg

    brian.brigg New Member

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    The only thing that I can see that might be improved is to get the stirrer outside of the refrigerator somehow as, in the picture shown, there is a lot of condensation on the stirrer unit which can't help its longevity. This would be quite difficult but not impossible but would require the fridge to be raised for clearance. I'm not sure how badly this would effect the insulation or if the stirrer might still be too cool which might actually make things worse. Maybe something shaft driven for stirring could be used but it is an interesting little problem to be solved.

    Great work on the build and getting around the flow problems, thanks for sharing.
     
  17. DBR_Reef

    DBR_Reef Well-Known Member Article Contributor

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    I'm sure the pump and stirrer are not helped by being in the fridge, but it looked a little worse than it is- I was taking the opportunity to defrost the fridge and it drips everywhere- I really wish I had used a fridge with auto defrost.
     
  18. Coralfuture

    Coralfuture Well-Known Member

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    This looks pretty slick! I may have to look into doing this myself in the future!
     
  19. DLHDesign

    DLHDesign Noob R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor Partner Member 2018

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    Great project! I wish I had somewhere near the tank where I could put a fridge - I'd build one of these for sure!

    When I converted my dosing containers to be "airtight" (to reduce evaporation effects), I used similar containers to yours and added an "input" line with some one-way valves. Works pretty well.

    Auto-defrost is basically just cycles of slightly warmer times. This makes for an easier fridge/freezer to clean, but doesn't really help in terms of maintaining food preservation. I think not using an auto-defrost fridge is a better idea, myself.

    Thanks again!
     
  20. Rick Mathew

    Rick Mathew Well-Known Member R2R Supporter Partner Member 2018

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    Great Video and write up....I also made a similar design and have been using it for almost a year now. My approach to keeping the food slurry suspended for feeding as to use air injected into the food chamber...My magnetic stirrer broke the food up more that I wanted...The air only comes on just before the feeding cycle starts and goes off shortly after the cycle is over. I also incorporated a temperature monitor into the slurry itself to record the mean kinetic temperature of the slurry to be sure to keep it at or below 30F...You can follow the details at this link...There are several threads to this that discuss the food preservation issue as well as the construction of the feeder.

    https://www.reef2reef.com/threads/diy-frozen-food-feeder.279232/#post-3386631

    I like you idea of chemically stabilizing the the slurry...I need to replace and clean the food chamber every 5 days and only using the low temperature as my means of preserving the food...I am going to give this a try...Thanks for taking the time to share this...Great post!!

    Rick
     
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