I have a couple questions...
1) How much breathable oxygen does 1 gallon of water hold?
2) How does oxygen normally replenish into water?
These questions have arisen because a player in my game has come up with a wonderful idea to avoid noxious fumes in the air. He wants to use create water to supply the group with fresh, clean water. Then, he wants to cast water breathing on the party, so they can breath the water. The water would go in a bucket (or similar airtight container) with a hollow reed attached to suck in the water.
He can cast create water at-will, so they will never run out of water. But I would like to know how often it will need to be cast. Every 10 minutes per gallon? Every 5 minutes? Every hour?
Also, I'm not sure if water automatically absorbs oxygen from the air it touches (and therefore, would absorb the poison in the air too)? Or if it has to ripple or bubble for the air to be absorbed? Or some other method? The reason I ask is because if simple contact is enough to absorb the air (and oxygen and poison), then the water container will have to be airtight.
reefwood wrote:
1) How much breathable oxygen does 1 gallon of water hold?
2) How does oxygen normally replenish into water?
Well, this is one of those scenarios in which it's probably best to not get overly nitpicky about the specifics in favor of allowing a player's ingenius plan to overcome an obstacle.
A gallon of water does not hold very much breathable oxygen. Plenty for a small fish, certainly, but not much for a human being. However, this is magic we're talking about here and the spell says it "allows creatures to breathe water freely." It doesn't say it allows them to treat water as though it were air. It says they can now BREATHE WATER. So the oxygen content shouldn't matter. The tidal volume of a human breath (that is, the median amount inhaled during one breath) is about 0.5 litres. There are roughly 4 litres to a gallon, so that's about 8 breaths, enough for roughly 30 seconds of non-strenuous activity (5 rounds).
As for how oxygen normally replenishes in water, that would be the result of aquatic plants converting CO2 to O2 much like their land-based cousins do.
1) The same amount of breathable air that 1 gallon of oxygen would normal allow (( not saying it is scientific, just that it would be game fair, for both air breathers and water breathers )).
2) Not much, many small pouds have a water wheel, to keep them oxygenation if you want to make sure your fish do not run out. Generally, you need fresh streams or rivers to feed fresh water into an area.
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Treat the Character as if he had a diving bell on his head. If you want to breath, you keep pumping oxygen in. If the bell if filled with water, then you would need to keep pumping in fresh water.
If it is water/air tight, (air or water) = Protected from noxious fumes
If it is not water/air tight = Then you are not protected from noxious fumes.
= I always dislike it when people say create water, at will. You create water with a canstrip. This requires you to spend One standard action per round casting a spell, each round .
You create 2 gallons/level. You need to created the water in open area, in open containers or downpour. You can not created it inside a creature, or a seal container.
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Still waiting for them to add a "Create Air" spell to Pathfinder
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Sounds like the player wants a 5th level Life Bubble, effect from APG.
Thanks for replies so far. I don't want to get too nitpicky about this, especially since it seems like a terrific idea to me, but I want to have some basics covered for how it will work.
1) That is a good point about the spell letting creatures breathe actual water, rather than giving them gills to breathe the oxygen in the water, and having it just be same as 1 gallon of oxygen makes sense too.
However, the closest comparison I can find for this is the bag of holding which seems to allow for 10 minutes of breathing. The time limit doesn't differentiate between different bag sizes or creature sizes, but the smallest bag is 30 cubic feet. Math tells me that 1 cubic foot would provide 0.33 min, so 20 seconds...which is not very long. The internet tells me that 1 cubic foot holds 7.48 gallons, and that an average bucket holds 4 gallons... so, 1 bucket would hold about 10 seconds of water... which just does not seem correct. Is my math off somewhere?
And when the water has been breathed up, do you think the bucket would be empty? Or would it just be full of unbreathable water?
2) It looks like an airtight container is the way to go. I'm thinking a bucket with an airtight cover and opening for the reed. Water can be cast into the bucket through the opening, and when the reed is put into place, it is sealed with wax. This process will have to be repeated each time the bucket is refilled. Also, each character can hold his breath for at least 2 minutes, so holding breath during this process won't be an issue, and even brief exposure to the noxious fumes won't usually be a problem because the Fort save will usually only be made 1/hr. Longterm exposure is the main problem.
reefwood wrote: And when the water has been breathed up, do you think the bucket would be empty? Or would it just be full of unbreathable water? When the water has been breathed up, the bucket will be full of the exhaled carbon dioxide, just as if the person were breathing air. This would also mean that, when they exhale through the reed, they'll be blowing bubbles in the bucket. Doesn't mean much mechanically, but might be an interesting thing to point out story-wise (and might also make stealth a little more difficult).
Fatespinner wrote: reefwood wrote: And when the water has been breathed up, do you think the bucket would be empty? Or would it just be full of unbreathable water? When the water has been breathed up, the bucket will be full of the exhaled carbon dioxide, just as if the person were breathing air. This would also mean that, when they exhale through the reed, they'll be blowing bubbles in the bucket. Doesn't mean much mechanically, but might be an interesting thing to point out story-wise (and might also make stealth a little more difficult). That is an interesting point. Although, this party rarely bother with stealth, and I imagine that they take the water in through their mouths by using the hollow reed, but they should still be able to breathe out the CO2 through their noses.
Anyway, 4 gallons of air being used in 10.66 seconds seemed awful fast to me, so I decided to do a quick experiment. I took a produce plastic bag (you know, those clear ones without handles...that probably hold between 1-2 gallons?), and I breathed in through my nose but breathed out through my mouth into the plastic bag. It only took about 5 or 6 seconds to fill up, so I guess we do breathe in a lot of air over just a few seconds.
One upside about rapid air/water use for this scenario is that it seems like the water would get used up too fast for the poison to absorb into it, and therefore, an airtight container is not necessary.
There are 6 people who need to use these buckets, so that would be a total of 24 gallons. The caster can create 24 gallons per casting. Since the buckets don't need to be airtight, the caster can create the water over the buckets, so that 1 casting can fill multiple buckets. Of course, some of the water will miss the buckets (maybe 25%?), but 2 castings should be enough to fill up all the buckets (1 casting per 3 buckets).
And if the bucket does get used up in 10.67 seconds, it seems fair to round that up to 2 rounds (6 sec/rnd), so the caster will need to cast every round to keep each trio of buckets filled as they run out every other round, but the caster can move and cast in one round, so this can be done without stopping or slowing down the group.
Of course, each person will need to use one hand to hold their bucket, and the caster will need to have his other hand free to cast every round.
Now they just need to round up some buckets ;)
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