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Old 02-01-2009, 09:58 AM   #5 (permalink)
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Default Re: Automatic Continuous Feeder - DIY

Part 5 of 5

Insert the bag into the chiller/towel, but be very careful to not bind the tubing where it connects to the bag at the bottom, and also keep the tubing in the middle as it leaves the chiller; you don't want it getting near the heat outlets on the sides of the chiller:

Now fold down the cap of the bag into the chiller:

Fold the remaining towel (if used) over the top, or if you used a filtersock, cover it. You'll have to experiment with how much towel to use, and how tight, so that it does not freeze:

Instead of a towel, you may try inserting a small filtersock:

Covering the filtersock loosely will keep the food less cold:

Covering the filtersock tightly will keep the food more cold:

Lastly, use the "prime" button again to bring the food all the way to the end of the tubing, and then push "run". It will begin by pumping one dose, and then the timer will wait for the next one. At anytime, you can push the "vol/total" button and it will display how many ml has been fed since you pressed "run":

To make any pump adjustments, push the "run/pause" button first (which pauses it), and then make your changes. You can reset the "total amount fed" to zero by pushing the "clear" button when it is displaying. You can turn the unit off while it's running or paused; when you turn it back on, it will be in the same state (run or paused) that is was in when turned off. And it remembers all settings, including total amount fed, even it you unplug the AC adapter.

Things to watch out for:

Bag positioning if noise is a concern: The chiller has a thermostat, but the annoying thing about it is that it clicks every 30 seconds or so as it adjusts temperature. If it's in your basement, then it's no problem. But if it sits on the tank like mine does, or if it's in your bedroom, then you don't want this clicking. The way to eliminate it is to put the temperature selector on the coldest setting. This causes the thermostat to always stay "cooling". This fixes the clicking. However the temperature can get very cold after a day or so, and if you seal the top of the chiller with a towel, then the food will eventually freeze. To prevent this, leave the top of the chiller loosely open, and don't push the bag in down to the bottom. Use a towel, loosely wrapped around the bag, to keep the bag from touching the metal walls or bottom of the chiller. This works; it won't freeze. But if you wrap it too much, then the food will not stay cold enough. So this is certainly one area where experimenting will help. Of course if you don't mind the clicking, the thermostat will keep the food perfectly at just above freezing for you.

Frozen spots: If you are using the "quiet" option where the chiller stays running constantly (no thermostat clicking), keep a close eye on the parts of the bag that touch the metal walls. If it's going to freeze, it will probably take 24 hours, or maybe even 48. So check it the next few days by pulling the bag out and squeezing/mixing it all around, especially the bottom where it connect to the tubing. If any part is frozen, then use paper or a towel to keep the bag away from the wall. Also, you could pull the bag up a little, so it gets more air. A good idea is to wrap the bag around the tubing, before you slide the bag in. You might also put a thermometer in with the bag, which sticks out the top, so you can see it while it's running.

Tube near heat: Watch where the tubing goes when it leaves the chiller and heads to the pump. Hot air exits the chiller on both sides, so you want to route the tubing along the back part. Avoid strong lights too.

Charger for pump: You don't need the AC charger to operate the pump, but you do need to plug it in once a month or so, for six hours, to charge it back up. So make sure you can get the charger cable to the pump, without having to move the pump. Of course, you could also just run the pump with the adapter connected, but that's one more cable going to the top of the tank.

Power failures: If the power goes off, nothing happens to the pump; it keeps working on its batteries. The chiller however will stop. But the important point is that this model chiller, when the power comes back on, will switch to full-cooling (no thermostat). This is fine if you were previously running full-cooling, but if you had a temperature set (because you did not mind the clicking), the food will freeze when the power comes back on. For this reason I really recommend the full-cooling setting to be used all the time.

Tube in display water: You want the tube to go into the tank water, so that it does not dry out. If kept above the water, food slowly starts drying out at the tip, slowly clogging it, and causing it to start spraying sideways.

First attempts: I recommend trying it first in your sink, using just water in the bag. Do everything including putting it into the chiller, and letting it run for a few hours. If ok, then fill with food and start it. This first time, and anytime you make changes to the bag, try not to do it right before you go to bed, because if you folded the bag too tight, or if it freezes, the "No Flow In" alarm will sound and wake you up. Better to do it in the morning.

Settings: When first trying to set the settings, it may sometimes not want to accept the numbers you try to set. This is because you have selected a dosing combination that is not possible. For example, if you accidentally set the rate to 0.1 ml per hr (instead of 600), and set the dose to 0.2 ml, and then set the interval to 1 hour, it won't accept it because if you dose 0.2 ml every hour, that is more food than the 0.1 that you set the rate for. Keep the rate at 600 and you should not get stuck as much.

Tubing replacement: The tubing "sets", according to the operating manual, are designed for 24 hours of use at 125 ml/hr. This is a total of 3 liters that the tubing would flow, before it starts to "wear out". Since I'm only pumping 0.4 ml/hr (.0004 L/hr), it would take 7500 hours, or 312 days, before the "wearing out" started to occur. And I'm sure the manufacturer is being conservative since someone's life is on the line. So 6 months (180 days) would seem to be a good replacement time at 0.4 ml/hr. If you were pumping 0.8 ml/hr, you would replace every 90 days, etc.

Proper pump model: Make SURE you get the Zevex EnteraLite Infinity blue pump. There are other EnteraLite pumps which are not Infinity, and they WON'T work. And there is another Infinity which is orange and not blue; it WON'T work.


Several things could be improved with more tinkering or more money:

Separate units: Reeds Foods recommends not mixing food unless just before feeding. This would be accomplished with the (expensive) addition of a chiller/pump unit for each type of food you feed (I use three).

Temperature alarm: Would tell you if the bag gets too warm, or if it starts to freeze. I imagine a freezer alarm would work.

Shorter tubing: The length of tubing from the chiller to the pump could be reduced by 6" or so, if you cut it and spliced it with a connector. You'd need to test it though, to make sure the food you are using can get through the connector. Mysis might be a problem.

Mixing: Although the crinkled and rolled bag will keep much of the food from sinking to the bottom, somebody should find a small, cheap paddle or servo that will shake or vibrate the bag every so often.

Fan quietening: The chiller uses a computer fan that runs all the time. On larger tanks the sound is not noticeable, but on smaller or quieter tanks, or tanks in your bedroom, the fan could be made slower/quieter by inserting a resister into the power lead of the fan. The chiller is powerful and freezes as is; less chilling won't hurt anything. You'll have to experiment with the resistor size.

Food types: With some experimentation, you could mix some solid foods (crushed flakes, tiny pellets, etc) into liquid foods, and maybe even add some type of thickener to it, to keep the solids suspended. Krill is too big for the tubing, but large mysis or small ghost shrimp should fit. Always test it first.

Related Information:

If you are have nitrate, phosphate, or nuisance algae problems, especially when dosing concentrated foods, you may find my other thread on Algae Scrubbers useful:

Article recommending continuous feeding:

Zevex Pump Manufacturer:

Ebay for medical devices (search for "zevex"):

Zevex operating manual:

One of the U.S. distributors of the chiller:

Chiller operating manual:
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