Aging saltwater
- Thread starter Gluestick
- Start date
mmgm
Premium Member
I use a maxijet 1200 to aerate my water..... Just turn on the powerhead and set the Venturi valve to disperse air into the water while the powerhead is on..... Basically you are oxiginating the water prior to making a water change......
Do this for 24 hours prior to water change and your good to go.....
Do this for 24 hours prior to water change and your good to go.....
Pandora
Premium Member
The "oxygenation" thing doesn't make much sense. Freshly made SW has already equalized with atmospheric oxygen (even if you were pumping in pure oxygen to saturate the water, as soon as you put it in the tank, this would happen). How much you can concentrate gas in a liquid depends on partial pressure of gas and the solubility coefficient, you're not going to change this buy putting it in the bucket overnight and pumping atmospheric air into it (um, you're the engineer--Henry's Law?)
Gluestick, there's no point in aging saltwater if you are getting it from your RO/DI. The only benefit I can think of is that you are giving it more time for the salt crystals to dissolve better, and this shouldnt' take longer than half an hour with a heater and a powerhead. The only reason I can think this myth might have gotten started was the idea from the old days of aging tap water. People do this because over time, chlorine can come out as a gas. However RO/DI should already have taken this out, along with other harmful substances, which don't dissipate as easily or at all, such as chloramines, phosphates and heavy metals. Or I should ask... are you (gasp) using tap?
Gluestick, there's no point in aging saltwater if you are getting it from your RO/DI. The only benefit I can think of is that you are giving it more time for the salt crystals to dissolve better, and this shouldnt' take longer than half an hour with a heater and a powerhead. The only reason I can think this myth might have gotten started was the idea from the old days of aging tap water. People do this because over time, chlorine can come out as a gas. However RO/DI should already have taken this out, along with other harmful substances, which don't dissipate as easily or at all, such as chloramines, phosphates and heavy metals. Or I should ask... are you (gasp) using tap?
mmgm
Premium Member
Pandora:
If you consider the fact that the solubility of a given gas in a given solvent (in this case salt water) is determined primarily by the partial pressure of the given gas in contact with the liquid and temperature of the system, I think mixing with powerhead as stated would contribute to oxygenation of the water. This is because for a given container filled with water the actual contact of air to water is limited to a relatively small surface area compared to total volume of water in a container. As a result saturation only occurs at this air/water interface.
Mixing the water with a powerhead allows "ALL" of the total volume of water in the container to be exposed to the gas (air) and subsequently saturate as you state according to Henry's Law. Allowing bubbles to mix with water through the powerheads provides additional surface contact of air/water and can only help in saturation or oxynization of the water.
In my case I perform 50 - 70 gallon water changes. It takes 24 hours to generate this amount of water using a RO/DI unit. At the end of this 24 hour period the water is stagnant and needs to be excited/mixed with powerheads. In addition to aiding in oxygenation the mixing helps dissolve salt into the water. If this process is not followed there is a risk of loosing livestock......
In any case I think you are partially correct and if you are mixing water in a large thin pan as a container your rational would be accurate. (Although UM not very practical) Also, I would not mix smaller volumes of water (ie 5 gallons) before water changes.
Sometimes it's best to leave the Engineering to the trained/Educated Engineers......
Cheers.....
Last edited:
Pandora
Premium Member
<a href=showthread.php?s=&postid=6708114#post6708114 target=_blank>Originally posted</a> by mmgm
Pandora:
If you consider the fact that the solubility of a given gas in a given solvent (in this case salt water) is determined primarily by the partial pressure of the given gas in contact with the liquid and temperature of the system, I think mixing with powerhead as stated would contribute to oxygenation of the water. This is because for a given container filled with water the actual contact of air to water is limited to a relatively small surface area compared to total volume of water in a container. As a result saturation only occurs at this air/water interface.
Mixing the water with a powerhead allows "ALL" of the total volume of water in the container to be exposed to the gas (air) and subsequently saturate as you state according to Henry's Law. Allowing bubbles to mix with water through the powerheads provides additional surface contact of air/water and can only help in saturation or oxynization of the water.
In my case I perform 50 - 70 gallon water changes. It takes 24 hours to generate this amount of water using a RO/DI unit. At the end of this 24 hour period the water is stagnant and needs to be excited/mixed with powerheads. In addition to aiding in oxygenation the mixing helps dissolve salt into the water. If this process is not followed there is a risk of loosing livestock......
In any case I think you are partially correct and if you are mixing water in a large thin pan as a container your rational would be accurate. (Although UM not very practical) Also, I would not mix smaller volumes of water (ie 5 gallons) before water changes.
Sometimes it's best to leave the Engineering to the trained/Educated Engineers......
Cheers.....
Heh, I'm aware that it happens at the air/water surface interface, and that your intentions are to increase surface area.
What I'm saying is that in practice, this increases the concentration of dissolved oxygen very negligably because it doesn't take much for the solution to come into equilibrium from its tap source. And I know this, I'm not guessing it, we actually ran a very similar experiment for a hydrolics experiment, taking measurements with a DO electrode meter (some of us started off as engineers before going to med school ).I agree with the part about dissolving salt, on the other hand (several hours is definitely better than half an hour if time is not a concern). This is a different issue, however, and not typically what people mean by "aging", and neither has anything to do with oxygenation.
Pandora
Premium Member
Oh, and here's Randy Holmes-Farley, answering the same question...
http://www.reefcentral.com/forums/showthread.php?s=&threadid=500820
http://www.reefcentral.com/forums/showthread.php?s=&threadid=500820
Mykayel
New member
I agree that there might be a small benifit by "aging" it for 24 ours in terms of disolved oxygen, but its not going to be significant. And either way, your water change is/or should only be a small potion of your total tank volume (i.e. 10% water change) so even if it had no disolved oxygen it wouldn't hurt your tank's inhabitants as it would only be a 10% drop in DO which would be quickly replenished by the water movement of your tank.
Easy there MGM, no need for insults. Besides, you wouldn't look good in a straight jacket. 
I think the post says aging SW not RO/DI. Aging does three things-
I think the post says aging SW not RO/DI. Aging does three things-
- Insures complete mixing
- Allows time for natural pH adjustment of the freshly mixed saltwater
- Allows time to bring it to tank temperature
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In my book it is a good practice especially to allow the pH to stabilize. On the other hand it is not the end of the world to use it right away if the RO/DI is already at tank temperature.
Pandora
Premium Member
Hey, I may have started that with being a little heavy handed in my first post... saying "that doesn't make any sense" and ending it with the engineer reference (though I stand by the other statements, since we did show it doesn't change O2 conc empirically). I stated it that way only as a segway to talking about Henry's Law, not meant in a nasty or snide way, though I can see how it could be misread as that... for that I apologize! Like I said, I have nothing against engineers, I trained & worked as a bioengineer for a few years, and it's only helped me in this hobby.
smoknreefrs
In Memoriam
i like to keep it simple.....
age the water as long as you want if time is on your side, what harm could it do????
age the water as long as you want if time is on your side, what harm could it do????
If I recall right a while back i was on some salt manufactuer website and they said aging the mixed salt water over night was so the salt could fully disolve into the water. Because it may be disolved to the eye in a short period of time doesn't mean that it is fully disolved and there is still some course particles. So if you added it to the tank right away they said these coarse particles would go threw the fishes gills which is not suppose to be good for them....... just what i have read........ so i just use a maxijet powerhead to mix the water overnight with no areation.........as i have read that pumping microbubles into the water doesn't do anything as it cannot absorb the o2 from the bubbles into the water anyway, just breaking the water surface is suppose to be suficient
Therbligs
Premium Member
Freshly mixed SW should be aged for the above reasons, and that it is considered a "Hot Solution" from an ionic standpoint, which can cause stress to sensitive creatures.
Use an old Rio 2100 for mixing in a 32gal trash can. I actually bring the DI water up to temp and then start to add salt slowly. Works great for me. Almost no clouding (3-5 min.) in the tank.
Use an old Rio 2100 for mixing in a 32gal trash can. I actually bring the DI water up to temp and then start to add salt slowly. Works great for me. Almost no clouding (3-5 min.) in the tank.
mdavis203
New member
I'm a relative newbie to reefs, but with this topic, I actually have some input...
Water is oxygenated within a 10-15 minutes with a decent powerhead (assuming the water is at the temperature desired). So 24 hours won't make a difference here.
The coefficient of solubility is dependent on temperature only (well, it depends on other things, but none that are applicable in this case). So, aging isn't an issue here, either, except the time it takes to heat the water.
I'm not familiar with idea of an ionic "Hot Solution" as Therbligs brings up, so I can neither conform nor deny that point. I'd have to research that further.
Water is oxygenated within a 10-15 minutes with a decent powerhead (assuming the water is at the temperature desired). So 24 hours won't make a difference here.
The coefficient of solubility is dependent on temperature only (well, it depends on other things, but none that are applicable in this case). So, aging isn't an issue here, either, except the time it takes to heat the water.
I'm not familiar with idea of an ionic "Hot Solution" as Therbligs brings up, so I can neither conform nor deny that point. I'd have to research that further.
