# Dry ice in a fish pond? **URL:** \ **Category:** Factual Questions\ **Created:** [October 7, 2005, 4:51pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214 "2005-10-07T16:51:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Sassafras\_Kid](https://avatars.discourse-cdn.com/v4/letter/s/c0e974/32.png) [@Sassafras\_Kid](https://boards.straightdope.com/u/Sassafras_Kid)\ **Post date:** [October 7, 2005, 4:51pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/1 "2005-10-07T16:51:18Z")
My brother wants to have a spooky Halloween party. One decoration we debated was placing a chunk of dry ice in his outdoor waterfall pond. The dry ice will be going into top pond (around 100gal) then empties via a waterfall into a lager pond (around 1000 gal), for hopefully a misty cascading effect. The potential problem is: The lower, larger pond is well stocked with koi and regular goldfish. Will the dry ice harm the fish? Will it make the water too cold or increase the CO2 levels too much? A recirculating pump keeps the water moving and the party will last around 4-5 hours. Thanks, ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [October 7, 2005, 5:04pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/2 "2005-10-07T17:04:20Z")
I don’t know about the fish, but I think the dry ice will be gone in a matter of minutes if you submerge it in water. ---
**Author:** ![Casey1505](https://avatars.discourse-cdn.com/v4/letter/c/dc4da7/32.png) [@Casey1505](https://boards.straightdope.com/u/Casey1505)\ **Post date:** [October 7, 2005, 5:27pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/3 "2005-10-07T17:27:30Z")
No worries, **Gabe**. The fish will be fine if kept submerged in water. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [October 7, 2005, 5:33pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/4 "2005-10-07T17:33:20Z")
I’d think twice about that, as the dissolved CO2 could severly lower the pH level of the water. Or the waterfall could knock the CO2 out of the water. I’d try a little bit, and run a pH test in both ponds. ---
**Author:** ![Garfield226](https://avatars.discourse-cdn.com/v4/letter/g/9e8a1a/32.png) [@Garfield226](https://boards.straightdope.com/u/Garfield226)\ **Post date:** [October 7, 2005, 6:24pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/5 "2005-10-07T18:24:28Z")
The effect you’re going for will work much better in hot water. I would be wary of the pH level in the pond, especially if you plan to have it smoking the whole time. You could partially submerge a pail of warm water in the top pond (so the top sticks out just a little) and put the dry ice in there. Same effect, no mixing of water. ---
**Author:** ![Casey1505](https://avatars.discourse-cdn.com/v4/letter/c/dc4da7/32.png) [@Casey1505](https://boards.straightdope.com/u/Casey1505)\ **Post date:** [October 7, 2005, 6:42pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/6 "2005-10-07T18:42:16Z")
And the mist will just cascade to the lower pond and into the air on the surface of the water without mixing with it, right? I’m just trying to get a mental picture. ---
**Author:** ![aamco](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@aamco](https://boards.straightdope.com/u/aamco)\ **Post date:** [October 7, 2005, 6:42pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/7 "2005-10-07T18:42:43Z")
> [@Maus Magill](#): > > the dissolved CO2 could severly lower the pH level of the water Seconded. Dissolving CO[sub]2[/sub] in water is a frequently-used trick in chemistry to effect a large pH change. A typical trick is to put an indicator in the water that changes around pH 5, and the dry ice will gradually change the color of the solution. The warm water suggestion is a good one, for two reasons: (1) it keeps the CO[sub]2[/sub]-saturated water separate from the pond, and (2) you want as much water vapor as you can to get the “misty” effect. The mist you see is just a low-flying cloud – the cold CO[sub]2[/sub] bubbles lower the temperature of the air below the dew point, and water vapor condenses. The warmer the water, the higher the dew point will be. Changing the bucket of water a few times over the course of the party probably wouldn’t be too bad. You’re going to have to drop in pieces of dry ice every 5-10 minutes, anyway. ---
**Author:** ![threemae](https://avatars.discourse-cdn.com/v4/letter/t/5f9b8f/32.png) [@threemae](https://boards.straightdope.com/u/threemae)\ **Post date:** [October 7, 2005, 6:45pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/8 "2005-10-07T18:45:45Z")
Yeah, I think that the carbonic acid will have the potential to harm the fish. Unless someone has some clinical trials that say that the koi will be fine, I would try the bucket suggestion mentioned. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [October 7, 2005, 6:54pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/9 "2005-10-07T18:54:52Z")
Try an experiement first on a friend’s fish, using your fish as the control group. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [October 7, 2005, 8:26pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/10 "2005-10-07T20:26:06Z")
> [@Casey1505](#): > > And the mist will just cascade to the lower pond and into the air on the surface of the water without mixing with it, right? I’m just trying to get a mental picture. The mist you see is water vapor, so that wouldn’t be too bad. If you were to use the separate bucket method, I would imagine the biggest danger to the fish would be the invisible, heavier-than-air CO2, which could sit on top of the lower pond. That shouldn’t be too bad if the pond is in a ventilated area. ---
**Author:** ![Valgard](https://avatars.discourse-cdn.com/v4/letter/v/7feea3/32.png) [@Valgard](https://boards.straightdope.com/u/Valgard)\ **Post date:** [October 7, 2005, 11:41pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/11 "2005-10-07T23:41:34Z")
> [@Sassafras\_Kid](#): > > …via a waterfall into a lager pond (around 1000 gal)… A pond with one thousand gallons of lager? Who do I have to know to get invited? ---
**Author:** ![zagloba](https://avatars.discourse-cdn.com/v4/letter/z/977dab/32.png) [@zagloba](https://boards.straightdope.com/u/zagloba)\ **Post date:** [October 8, 2005, 11:55am UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/12 "2005-10-08T11:55:02Z")
> [@Sassafras\_kid](#): > > empties via a waterfall into a **lager** pond (around 1000 gal), for hopefully a misty cascading effect. The potential problem is: The lower, larger pond is well stocked with koi and regular goldfish. If they’re swimming in beer already, I don’t see how a little dry ice will do them any harm. ---
**Author:** ![Gary\_Robson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gary_robson/32/3448_2.png) [@Gary\_Robson](https://boards.straightdope.com/u/Gary_Robson)\ **Post date:** [October 8, 2005, 7:21pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/13 "2005-10-08T19:21:00Z")
If you drop large chunks of dry ice into a bucket of water, they will bubble like mad for a while, and then a coating of ice (water ice, that is) will build up around the dry ice, helping to insulate it. You’ll still get a little trickle of gas from it, but the major bubbling will stop. Either you have to keep adding small chunks regularly, or you need to break the big chunks up to get the ice off of them. I would definitely put the dry ice in a bucket of water partially submerged in the upper pond, by the way. It wouldn’t be very good for the fish. Another possibility is to go to a party supply store and rent a fog-maker. They’re not that expensive. ---
**Author:** ![Khadaji](https://avatars.discourse-cdn.com/v4/letter/k/9e8a1a/32.png) [@Khadaji](https://boards.straightdope.com/u/Khadaji)\ **Post date:** [October 8, 2005, 9:16pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/14 "2005-10-08T21:16:15Z")
I just came from my local Toy R Us and they had a fog maker on sale for 30 bucks. Maybe yours does too. ---
**Author:** ![Sassafras\_Kid](https://avatars.discourse-cdn.com/v4/letter/s/c0e974/32.png) [@Sassafras\_Kid](https://boards.straightdope.com/u/Sassafras_Kid)\ **Post date:** [October 9, 2005, 3:26am UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/15 "2005-10-09T03:26:54Z")
Lots of good ideas, Thanks. I wonder what comes out of the fog machine? Would it be toxic if it condenses on the water? ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [October 9, 2005, 4:11am UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/16 "2005-10-09T04:11:19Z")
> [@](#): > > Loss of consciousness in fish immersed in carbon dioxide saturated water (pH level 4.5), which is highly aversive, can take 7–8 minutes. Fish will show head shaking and vigorous tail shaking for up to two minutes after immersion in the solution. Movement then subsides and the fish become still after five minutes. This is due to narcosis (loss of control of movement) and exhaustion as opposed to insensibility. Unless fish are kept in a high concentration solution for 7–8 minutes, recovery will begin soon after removal from the solution [Fish Welfare at Slaughter](http://64.233.161.104/search?q=cache:uvQqqO_no70J:seafood.ucdavis.edu/pubs/fishwelfare.pdf+%22carbon+dioxide+saturated+water%22+pH&hl=en&client=firefox) ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [October 9, 2005, 5:13am UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/17 "2005-10-09T05:13:23Z")
> [@Sassafras\_Kid](#): > > Lots of good ideas, Thanks. > > I wonder what comes out of the fog machine? Would it be toxic if it condenses on the water? dry-ice + small amount of water = carbon dioxide fog. ---
**Author:** ![Khadaji](https://avatars.discourse-cdn.com/v4/letter/k/9e8a1a/32.png) [@Khadaji](https://boards.straightdope.com/u/Khadaji)\ **Post date:** [October 9, 2005, 12:30pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/18 "2005-10-09T12:30:18Z")
> [@Sassafras\_Kid](#): > > Lots of good ideas, Thanks. > > I wonder what comes out of the fog machine? Would it be toxic if it condenses on the water? I dunno for sure, but as I understand it, it is simply water vapor. Again, as I understand it, the machine vibrates rapidly enough to take water and turn it into fog. Maybe someone with a better understanding of how it works will come along… ---
**Author:** ![Sassafras\_Kid](https://avatars.discourse-cdn.com/v4/letter/s/c0e974/32.png) [@Sassafras\_Kid](https://boards.straightdope.com/u/Sassafras_Kid)\ **Post date:** [October 9, 2005, 2:07pm UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/19 "2005-10-09T14:07:58Z")
Most store-bought fog machines that I have seen come with some kind of liquid chemical that you add to the machine. They also have a smell to the fog. So it may be an ultrasound vibration, but it’s not just water thats getting “fogified” ---
**Author:** ![Seven](https://avatars.discourse-cdn.com/v4/letter/s/3d9bf3/32.png) [@Seven](https://boards.straightdope.com/u/Seven)\ **Post date:** [October 10, 2005, 6:38am UTC](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214/20 "2005-10-10T06:38:13Z")
Fog machines use glycerin in water (fog juice) and heat to create the fog. [Next page](https://boards.straightdope.com/t/dry-ice-in-a-fish-pond/325214.md?page=2)