Automatic Frozen/refrigerated food dispenser

[newbreefer316]

Following, I've been looking into different ways to setup a refrigerated auto feeder for my Reef Nutrition foods.

 

[Rick Mathew]

wow...
any updates on this guys? sure would love to try this. i love to feed my DIY fish food why I travel.
hows this working for you guys that did it? worth the time/effort/ expense?

My system is also working fine. I made some modifications. I no longer Use the DOS pump but switched to the pump that DBR_Reef recommended. Getting the right temperature is a challenge ...as low as possible without freezing up, but it just takes trial and error to get there....It is defiantly wort the time/effort and expense to have this when you travel....will post some new pictures later today

 

[Rick Mathew]

wow...
any updates on this guys? sure would love to try this. i love to feed my DIY fish food why I travel.
hows this working for you guys that did it? worth the time/effort/ expense?

Here are the pictures I promised

THIS IS THE BASIC SETUP

WATER FLOWS FROM SUMP--THROUGH THE "T" CONNECTION WHERE THE FOOD IS INJECTED INTO THE STREAM THEN IT FLOWS INTO THE TANK
WATER FROM THE SUMP IS PUMPED BY A SEPARATE PUMP HOOKED TO MY APEX AND STARTED AT FEEDING TIMES AND SHUT OFF AFTERWORDS.

TO PREVENT CONDENSATION IN THE AIR LINE AND HAVING IT FREEZE OVER I CONSTRUCTED A DESICCANT SYSTEM TO DRY THE AIR...WORKS GREAT!

THIS IS THE PUMP I GOT FROM EBAY WORKS WELL

https://www.ebay.com/itm/12V-Large-...e=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649

I CONTROL THE PUMP WITH MY APEX. IT RUNS ABOUT 7-9 SECONDS TO DELIVER THE AMOUNT OF FOOD I NEED.


All of this requires some tinkering to get the parameters where you need them...To get the temperature as low as possible without freezing...to get the amount of food correct...but all in all worth the effort

Hope this helps...be happy to answer any other questions.

Rick

 

[Reefhack]

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)(Amazon product) 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.

I know this post is two years old but it’s the basis for my future auto feeding expedition. The link to the pump you used isn’t available anymore and I wanted to make sure I bought the correct peristaltic pump. Great write up & video btw!!!

 

[Rick Mathew]

I know this post is two years old but it’s the basis for my future auto feeding expedition. The link to the pump you used isn’t available anymore and I wanted to make sure I bought the correct peristaltic pump. Great write up & video btw!!!

This one should do the job ...Very similar to the one I use

https://www.ebay.com/itm/12V-DC-Lar...=2643340874785ab14b52bcd54b819e8a89cf22f5045d

 

[Reefhack]

This one should do the job ...Very similar to the one I use

https://www.ebay.com/itm/12V-DC-Large-Flow-Peristaltic-Pump-Corrosion-Resistant-Peristaltic-Metering-Pump/264334087478?_trkparms=ispr=1&hash=item3d8b8a1536:g:NG8AAOSwbRdc5p4m&enc=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&checksum=2643340874785ab14b52bcd54b819e8a89cf22f5045d&enc=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&checksum=2643340874785ab14b52bcd54b819e8a89cf22f5045d

Thanks Rick. I’ve been voyeuring and gleaning from R2R for over a year now and you’ve always been a source of much valued info. Kudos my friend!!
Mike

 

[Rick Mathew]

Thanks Rick. I’ve been voyeuring and gleaning from R2R for over a year now and you’ve always been a source of much valued info. Kudos my friend!!
Mike

That is very kind of you to say Mike....I do enjoy this hobby and love to share what I have learned...If you need any more info just let me know...I have been using my Auto frozen food feeder for going on 2 years...There a lot of "tweaking" to get it to be dependable...be glad to help

Explore---Learn----Share

 

[DBR_Reef]

I know this post is two years old but it’s the basis for my future auto feeding expedition. The link to the pump you used isn’t available anymore and I wanted to make sure I bought the correct peristaltic pump. Great write up & video btw!!!

Yeah, what Rick said on the pumps. I didn't really have any problems with the pump I bought, but I did eventually have problems with the silicon tubing- it would crack and start leaking- and the time it took seemed to be random, so I couldn't just replace it regularly. Eventually I replaced that pump with a industrial pump with a masterflex 7018 head- I think it only cost me $30-40. I switched so that I can use pharmed tubing which is good to something like 3000 hours, and is very reliable. The 7018 head also uses tubing that has a 3/8 ID, so it is even larger than the original pump.

I'm not seeing anything super cheap right now on ebay, but this one would certainly work (I use the same motor for auto water changes), and cheaper option do pop up. https://www.ebay.com/itm/AMICON-LP-1-PERISTALTIC-PUMP-w-7018-Cole-Parmer-Pump-Head/273951133401?

If you do end up going with a masterflex head pump and need some tubing, I can send you some- I think I have more than I could ever use. If you end up going with a cheaper pump I would still recommend replacing the silicon tubing with pharmed tubing- You can find generic size pharmed tubing sold by the foot cheap on sites like US plastics. The longevity is well worth it.

 

[YankeeTankee]

Awesome write up! What about instead of pumping food into the T thats off the manifold, having a second peristaltic pump hooked up to a RODI container inside the fridge. The RODI doser is turned on after the feeding is done and enters a Y site in the fridge with a check valve to prevent water from entering the food container, this flushes all of the external portion of the tubing.

Now if only I knew where to find these y sites that have incorporated check valves. Gotta look around.

Does this seem reasonable?

 

[LadyTang2]

Great write-up. Been running something similar on my system since this summer, but I do use the reef nutrition foods. Let's me have more precise control over what particle size goes in at what times. (I feed oyster feast and phyto at night for corals and filter feeders since they'll feed 24/7 and the mysis and roe go during the day)

These feeders help your fish exhibit more natural behavior rather than just swimming at the glass when they see you. Well..... my rabbitfish still does, but that's because he's a pig. I also think fish are healthier with lots of small feedings throughout the day, especially schooling planktivores like fairy wrasses and anthias.

My system has a constant flow of water ran into the fridge through pvc as can be seen in the 2nd pic. The murloc T ties in the dosing line. Prevents any exposure of food to above refrigerated temps until it hits the water. This line is fed from the manifold on the fuge and frag tank pumo and then discharges directly above the main return intake and is then distributed through the 4 return nozzles in the display.

Did you ever had any issues with pressure being too great in the tank water line so it prevented the dosing pump from being able to force food into that pipe? How did you account/view this?

Anyone who understands flow/fluids help me out with when how you know you would have enough force in a setup like this?

 

[Labridaedicted]

Did you ever had any issues with pressure being too great in the tank water line so it prevented the dosing pump from being able to force food into that pipe? How did you account/view this?

Anyone who understands flow/fluids help me out with when how you know you would have enough force in a setup like this?

Nope. It has it's own dedicated pump to circulate the water. It just outfalls right in front of the intake of the main return. It cant outcompete the pressure of the return and I would expect that would even cause the dosing pump to fail and allow water to push out into the bottles.

The idea is to have minimal or no backpressure on the fees lines. The recirc pump is dialed back via a valve diverted line so that the water going through the Teed in food lines is only flowing through freely, not pressurized.

 

[Rick Mathew]

Awesome write up! What about instead of pumping food into the T thats off the manifold, having a second peristaltic pump hooked up to a RODI container inside the fridge. The RODI doser is turned on after the feeding is done and enters a Y site in the fridge with a check valve to prevent water from entering the food container, this flushes all of the external portion of the tubing.

Now if only I knew where to find these y sites that have incorporated check valves. Gotta look around.

Does this seem reasonable?

My experience with check valves has not been good....The clog up and block the flow...The food passing through them is large enough to cause a problem...Might be if larger tubing... ie. larger check valves that might work


rick

 

[YankeeTankee]

@DBR_Reef any updates? Still using the same preservatives? How often do you replace the food?



Any other new ideas anyone?

 

[Rick Mathew]

@DBR_Reef any updates? Still using the same preservatives? How often do you replace the food?



Any other new ideas anyone?

I am still using mine 2 years +...Am very pleased with how it works...No major modification...The biggest challenge is keeping the frig temp constant...It is not a terrible problem just one of those nagging ones..I try to keep my food slurry below 34 F ...my target is 32 or below (my slurry is in salt water 35 ppt so the freezing point is about 28 F...There are occasions where the frig will go super cold and freeze the tubes and slurry but it is not a too often...I keep my food for 7 days with no apparent issues...I monitor my temp with my Apex as well as a LogTag monitor just to keep track of the Mean Kinetic Temp. The Apex is mostly to notify me if the temp gets out of range...works well

rick

 

[YankeeTankee]

I am still using mine 2 years +...Am very pleased with how it works...No major modification...The biggest challenge is keeping the frig temp constant...It is not a terrible problem just one of those nagging ones..I try to keep my food slurry below 34 F ...my target is 32 or below (my slurry is in salt water 35 ppt so the freezing point is about 28 F...There are occasions where the frig will go super cold and freeze the tubes and slurry but it is not a too often...I keep my food for 7 days with no apparent issues...I monitor my temp with my Apex as well as a LogTag monitor just to keep track of the Mean Kinetic Temp. The Apex is mostly to notify me if the temp gets out of range...works well

rick

what pump and diameter tubing are you using? Is it the pharmed tubing?

You have an apex temp probe in the food container?

I had just figured my slurry would be in rodi but I guess lowering the freezing point with nacl is a good idea! It doesnt degrade the food further right?

7 days is great but I was hoping for 2 weeks, ever try that?

One last q, are you using many of the preservatives like DBR ie citric and propionic acid?

Thanks Rick

 

[Rick Mathew]

what pump and diameter tubing are you using? Is it the pharmed tubing?

If you go to post # 1 in the thread DBR_Reef posts a list of the equipment he used...This includes the pump and the tubing...This is what I am using currently I think it is 3/8 ID silicone tubing​

You have an apex temp probe in the food container?

Yes I put an APEX Temp probe into the container...​

I had just figured my slurry would be in rodi but I guess lowering the freezing point with nacl is a good idea! It doesnt degrade the food further right?

7 days is great but I was hoping for 2 weeks, ever try that?

I only do seven days cause that is all my container will hold...I use DBR's preservative which he states the food could be good up to 3 months.....So I would guess 2 weeks should be fine....I think the key is keeping it cold enough​

One last q, are you using many of the preservatives like DBR ie citric and propionic acid?

Thanks Rick

what pump and diameter tubing are you using? Is it the pharmed tubing?

If you go to post # 1 in the thread DBR_Reef posts a list of the equipment he used...This includes the pump and the tubing...This is what I am using currently I think it is 3/8 ID silicone tubing

You have an apex temp probe in the food container?

I had just figured my slurry would be in rodi but I guess lowering the freezing point with nacl is a good idea! It doesnt degrade the food further right?

7 days is great but I was hoping for 2 weeks, ever try that?

One last q, are you using many of the preservatives like DBR ie citric and propionic acid?

 

[Dom]

I just finished watching the assembly video. I think this is a wonderful system and within my skill set to build.

But I do have questions...

You have set up (for lack of a better description) a closed loop system. Using a "T" in the loop, you've connected your food source.

When your pump comes on, it injects "food slurry" into the flow of the loop and into the sump. So if I understand, you are relying on your return pump to pick up the food and pump it into your display. Is this correct?

Also, what prevents from water traveling through the loop from backing up into the food reservoir? I'm thinking a check valve, but, I'd worry about food slurry causing it to get stuck in the open position.

 

[DBR_Reef]

I just finished watching the assembly video. I think this is a wonderful system and within my skill set to build.

But I do have questions...

You have set up (for lack of a better description) a closed loop system. Using a "T" in the loop, you've connected your food source.

When your pump comes on, it injects "food slurry" into the flow of the loop and into the sump. So if I understand, you are relying on your return pump to pick up the food and pump it into your display. Is this correct?

Also, what prevents from water traveling through the loop from backing up into the food reservoir? I'm thinking a check valve, but, I'd worry about food slurry causing it to get stuck in the open position.

The peristaltic pump acts as the check valve, preventing water from being pushed into the reservoir.

 

[Reefhack]

A Venturi tee will also create negative pressure and draw the food into the line.

 

[Dom]

The peristaltic pump acts as the check valve, preventing water from being pushed into the reservoir.

duh... of course.

And am I correct; the food is being picked up by the return pump?