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Use an Aquarium Pump to Freeze Objects Inside Ice Blocks

6a00e553b3da20883401b8d159845d970c-580wiYou can make a clear block of ice using an insulated cooler with the Directional Freezing method. You can also use this method to freeze objects inside of ice blocks including freezing a full-sized bottle inside an ice block.

If you are able to add an aquarium pump to the mix, you can make clear ice from the bottom up without any cloudy parts at the end; a method that mimics how professional ice block machines work. 

(All of the many, many ice experiments posts are located here in the Index of Ice Experiments.)



Today we'll talk about how to make clear ice with an aquarium pump and no cooler, and how this same method allows us to freeze objects in an ice block also without an insulated cooler.


While I've always favored the non-electricity Directional Freezing method, Alcademics reader fang2415 prefers to use an aquarium pump without (much) insulation. This takes up little less space in the freezer, and it seems like a much faster method than with insulation - as below, he says he gets a 4-liter ice block every day! 

In short, fang2415 places an aquarium pump at the top of an uninsulated container of water in the freezer, just barely insulating the top of the container with bubble wrap to help prevent it freezing over. He then found that this also works to freeze objects inside ice blocks. 

He describes the method:

The method is really simple: basically it's the same thing I now do to make most of my ice using an aquarium pump in a plain Tupperware-style plastic 5L container, but this time I threw a bottle inside the container and used tinfoil as a cover since the bottle was too tall for the lid to it.



I've been making all my ice this way recently, and every day I get a big beautiful 4-liter-or-so block of ice. The only real annoyance is cutting the pump out. 

I filled the container up to about .5 inch from the top and stuck my 150 L/H aquarium pump to the side just below the surface. Usually I aim the pump so that the outlet goes across the middle of the surface, but this time I kept it to one side so that the jet went around the side of the bottle's neck.

I've found that insulation barely matters with the pump method, although I usually cover the top with two layers of bubble wrap to reduce freezing at the top. Tying the bubble wrap with string works just fine; it just means that you need to knock the top ice-collar off at the end.

After chiseling the pump out (which is probably the most difficult part of the process), I had a bottle with the top conveniently exposed inside a large squarish block of clear ice. 


He then chisels out the aquarium pump and cuts or runs water over the outside edges to smooth out the block of ice and make the bottle label more legible. 

Thanks once again to dedicated ice nerd fang2415 for not only doing the experiments, but for taking pictures and sharing with the Alcademics audience!




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Is there an easy way to make the bottle slide in and out of the block? So that the ice block is in effect a cooler?


Hmm, seems like there should be (with a straight-sided bottle at least)? My first impulse would be to wrap the bottle tightly with foil before freezing, since the foil should conduct heat well enough to melt the ice just around the bottle. There might be other ways too -- maybe you could empty the bottle after freezing and fill with cool water that would melt some ice but not break the bottle, then dry the bottle and refill with the original booze?

I think no matter what you do, I think there's a good chance that you'll get some melting around the hole, so the bottle may end up fitting loosely after a while. But it sounds worth a try to me! You might need to get a pump and test it yourself though -- my freezer is short enough that it only fits half-size bottles, so my ability to test bottle-freezes is a bit limited...

Camper English

Agreed with fang. Easy way for sliding is to put the bottle in only up to the wide part in the water (remember ice will expand so leave another 3/4 inch or so of room); then you don't have to worry about chipping out the neck. It will only work for one bottle style of course.

All of fang's other suggestions seem great to me. I wouldn't fuss with foil personally- small cracks can get stuck in the ice and be hard to remove without ripping. I've had that problem when trying to use plastic bags and such.


For making a cooler for sliding bottle in and out, I would think that if it is a spirit you enjoy often, you could save an empty and use that when making the block. That way you don't have to empty an encased full bottle. When block is frozen, add cold water into empty bottler until bottle releases then add new bottle.


Very cool! I could also envision fastening weights to 50 ml bottles with differing lengths of fishing line to create a frozen matrix of booze.

Camper English

I used fishing line sideways (across the top where it freezes first) in my cooler to make this:


I thought of doing that, but my worry was that the ice around the bottle might expand as it froze and break the glass. Freezing a bottle filled with water worried me too since the inside or outside might freeze first and break it in one direction or the other?

But I dunno, maybe I'm just a worrywart; I guess just be careful if you try it that way?


Hey Fang2415,

Good job be the way!
Do you thing one of this pump works better then yours?




My guess is that pump probably won't work quite as well since a) it might freeze too quickly sticking out of the water like that and b) it looks like it might not create enough of a current at the top? (120L/H is a little lower than my pumps, and I've found that the advertised ratings are often way too high anyway.)

But I'm only guessing here -- it's so cheap that it might be worth a try? The one other thing I can see is that the intake hose might stick down a little too deep, but maybe it could be trimmed shorter so that is stays in the liquid water...

Incidentally, since sending the email to Camper, I've improved my rig somewhat: I bought this pump, whose nice compact shape is much easier to get out of the block; and this slicing knife, whose right-sided bevel makes it a really good tool for a right-hander like me to break up ice. It now usually takes me less than a minute to get the pump out!


Silly question, but does the freezer door shut all the way with the cable hanging out?


After all the months I spent trying ice rigs, I don't think there are any silly questions! There is always a little gap around the cord (maybe a couple millimeters on either side). I try to lay the cord so that it lies flat in order to minimize this, but I think a little gap is inevitable. But the gap is definitely small enough that the door does close securely and snugly otherwise. So I guess it depends on what you mean by "all the way"?

I'm not sure it makes a big difference though; I think my (non-defrosting) freezer frosts up a little sooner as a result and presumably runs a little less efficiently as well. But it doesn't seem to affect temperature significantly -- having taken a look just now, the bottle of vodka I've got in the freezer has chunks of ice in it despite the cord which is currently sticking out of the door...



All right! Roger! So what you think about this one?

The pump sucks and pull water, its possible to place one hose in one corner and the other in the opposite side. It makes the water circulates right?

Is that perfect?

Another question, now you make it in a simple tupperware and not a cooler. Is thatfine or in a cooler is better?

Thanks a lot!



I've found in doing this with my rig, that if I let the cord come out the side of the door but nearer to the top than bottom I get less frost and less heat loss. :-).



I've found the bottles don't break since the ice freezes on top last it doesn't exert too much pressure inwards on the glass. The only time I had one break was when I filled it with water to sink the bottle and the water inside froze first and broke outwards. I guess this means that if you want to sink the bottle easily you should use liquor in the bottle or rocks instead of water.


Interesting, thanks for the tip (another one from my pump-ice hero)!

I wonder if it might have to do with airflow inside the freezer (from a fan on top maybe)? Do you have a good way of measuring the increased frost / heat loss? I'm not sure the change in my frost is so big that I would know for sure that it was the cord causing it, and the heat loss is even trickier since the only noticeable consequence would be more electricity usage to maintain the same temperature...


I can only measure frost over a period of a week when making multiple blocks and I just physically measure the thickness. I assume since the cord is on the side rather than top it keeps moisture from "falling" in.

To measure the temperature I used a temperature probe and data logger over a 48 hours period and saw that the temperature of the air in center of the freezer was cycled less (when the cord was higher) which means the compresser did not need to kick on as often to re cool the freezer.

Fun note, when freezing approx. 14L of water and only leaving 1.5L liquid in the end leaves a very dirty looking water. Generally water in Norway is considered very pure but when condensing all the minerals and contaminates that much it looks like piss. (selling note of clear ice is that you aren't drinking that part) :-)


Ah, cool -- that's interesting that the temperature data shows a difference in the cycle time. I oughta get me one of those data-logging thermometer rigs -- did you order yours from somewhere or did you hack it together yourself?

As for the water left on top, yeah, the stuff I get on top at the end of the freeze looks almost like skim milk. (Camper trimmed my description for length and readability and I think he cut the part where I pour the last water off the top.) I tasted it once and it was like drinking river silt. It does make me flinch now when I get cloudy ice and watch the minerals fall out as it melts... London water is especially gross (280 ppm solids at my house!), so yes, that is a big selling point for the clear stuff!


I used a small DAQ unit I had form university to connect my temp probe.

You're braver than I am, I would not want to try the water coming off the top of my blocks.

The only problem I have left is figuring out how to be cool and break ice with a pick, my blocks might be too large or not uniform enough but I can never break them through properly. I've started using a hot wire now which works amazingly, if a bit slow.

I need to learn this guy's tricks,


Hey, sorry, I just now saw this. The only thing that might be tricky about that pump is that those inlet and outlet pipes might make it a little harder to get out of the ice (although maybe they're removable?). But other than that it looks pretty good to me. I haven't been able to experiment with hoses, but that might open some interesting new possibilities...

As far as the container goes, the trick is that you don't want insulation on the bottom (since we're freezing from the bottom up). So if you used a cooler you'd have to saw the insulation off the bottom like Nome did. I've found that even with no insulation at all it works okay -- you might just have to periodically break up ice that forms over the top. So for me it hasn't been worth it to try sawing through a cooler.

I think insulation does help though, although the difference is pretty minor (I can't remember when exactly, but sometimes I have seen a small amount of cloudiness when something weird happens, like if I'm putting the pump in the wrong place, or I'm trying to freeze around irregular objects, or to stop the freeze flat at a particular height). When I want to add insulation, I get a styrofoam pipe insulator (like this), cut it in half the long way, and duct-tape it snugly in a ring around the container. Then I can add as many rings of insulation as I want to the sides of the container. I usually only use one at the top edge in addition to the bubble wrap, but if I want to be extra-careful with the freeze then I can add a few more, even going all the way down so that only the bottom is uncovered. Again, not sure whether it works quite as well as sawing through a cooler, but it works well enough that I haven't bothered to check!


Ah yes, figuring out the best way to break up the block is something on which I've spent nearly as long as I did figuring out how to get the ice in the first place!

As I mentioned in a comment above, recently I've dramatically improved my ice-breaking technique by using this serrated knife. I got started on this from a passage in Dave Arnold's book in which he describes how you first score the ice with the knife and then tap the back of the knife with a mallet to cleave it into nice perfect columns. He even goes on to say how easy it is and how anyone can do it.

So, I tried that several hundred times over about nine months and felt like a crazy idiot for getting nothing but crooked splits and ice chipping off all over the place, until finally I realized what was going on. The edges of serrated knives are asymmetrical: one side is flat and the other has a bevel like a normal knife edge (about 22 degrees for Western-style knives). When you tap the knife's spine, the knife redirects the force symmetrically from its edge -- so when I held the knife upright, the cut would go off crooked at an 11-degree angle. So now I try to hold the knife at about an 11-degree angle to the vertical to correct for this. It's not easy to get this right, but when I do I can send a straight, flat cut through a block of ice six inches thick, just as Arnold suggests.

The other thing I noticed is that different knives are asymmetrical in different directions: all the bread knives I've seen are flat on the right side of the edge, whereas all the serrated knives for slicing meat are flat on the left. This doesn't make a big difference for splitting a block (you just have to angle it the other way), but it does make a huge difference for shaving surfaces. What I've found is that holding the flat side of the knife edge against a surface makes it very easy to shave the surface flat or into the shape you want; but pressing the beveled side of the knife edge against the block is no good at all: it just slips right off. For me as a right-hander, this means that a slicing knife is a great ice shaver (since when I saw with the knife I push it leftwards against the surface of the ice, toward my body and toward the flat side of a slicing knife's edge); whereas bread knives are useless to me as ice shavers.

Anyway, maybe some of that will help? I still have plenty of room to improve, myself -- I've watched the first two seconds of that Ueno-san video about two hundred times trying to figure out how he splits it so cleanly. (All I can work out is that maybe it's that amazing cleaver?) But yes, rest assured that you're not alone in wanting to improve your ice-splitting technique...


I will give your tips a shot, I had given up and used a hot wire because I began to think it had more to do with "our" ice freezing from all sides rather than professional blocks from only one side, creating nice lines for the ice to break straight.


Yeah, that was one of my early hypotheses too, but I stopped worrying about it once I started getting straight breaks.

Admittedly I have found that my ability to get straight breaks is much better when splitting a block symmetrically and with plenty of space on either side of the split than it is when trying to split near an edge. (So for example splitting a 4X6X6 block into two 4X6X3 blocks works well, but it's much harder to split a 4X6X1 sheet off one side, and even a bit tricky to split it into two 2X6X6 blocks.) I suspect this is inevitable -- based on what the guy says at the start of this this (impressive) video, the same holds true for splitting stones, which looks to me like basically a heavier-duty version of the same process.

It is true though that my freezes start out roughly U-shaped up to the point of insulation, above which they level off. I have found that when I insulate the container all the way down, the freeze stays almost completely horizontal as it proceeds upwards. I don't usually do that since it slows things down a lot, but maybe next time I'll try it and see if it makes it easier to split the block closer to an edge...

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