herefishiefishie Posted January 17, 2007 Report Share Posted January 17, 2007 .... cause I am special. So I've noticed. So Jacko where were you at the start of the post :roll: :lol: Humidity also affects the rate of evaporation as the surrounding air nears its saturation point, it is unable to pickup anymore water molecules. & My rudimentary understanding is that the fan increases evaporation by increasing the kinetic energy in the water molecules at the surface. ie their speed. The faster they are moving, the more energy they have to break the surface tension. As the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. You can speed up molecules a number of ways but the obvious ones are increasing their temperature or increasing the air movement at the surface and this is what the fan does. You could of backed me up on the if it works in sub tropical Gold Coast it will work in New Zealand. :lol: Let me guess the heat wave over now. 8) Frenchy Quote Link to comment Share on other sites More sharing options...
Aaron_fish_mad_guy Posted January 18, 2007 Report Share Posted January 18, 2007 "You have to be careful with ice cubes too. When you freeze water, you change the composition of it. " what the! does someone think H2O changes to something else when its frozen ... Believe the science teacher --- it stays H2O .... just changes state! Quote Link to comment Share on other sites More sharing options...
Stella Posted January 18, 2007 Report Share Posted January 18, 2007 I have never used a fan, was to worried about moisture build-up, especially as we owned our own home. Well, since he dumped me a few months back and i have returned to renting I don't care so much and thought I would give it a try. Ok so it has only been two days, but for the first time in two weeks the chiller is off and the temp is a few degrees below what it needs to come on! It is not just a break in hte weather either, it has been similar temps inside over the past week so far as I recall. I'm impressed!! (I have been using a scientific thermometer I borrowed off a friend. It is amazing how many degrees out some of my other thermometers are... even the chiller is out by at least a degree.) So I dont understand a lot about electricity, but the fan is 20 watts and the chiller is 190 watts.... I think I would rather have the fan going 24/7! Quite a relief as I am getting some kokopu on tuesday and was stressing about getting it cold enough for them. Stella Quote Link to comment Share on other sites More sharing options...
Jacko Posted January 18, 2007 Report Share Posted January 18, 2007 Well bascially we have said the same thing though your way is alot more technical I should have said the Air feels colder at the start of my last post Also your right as the Humidity gets higher this method works slower though it will still work in a humid area until 100% saturation is reached" Sorry Freakyfish, yes I do agree that the fan method is the most practical way of keeping the water temperature down. I just misinterpreted your explanation why. This is that the process of evaporation is the principle reason for the cooling. Quote Link to comment Share on other sites More sharing options...
herefishiefishie Posted January 18, 2007 Report Share Posted January 18, 2007 oops, my bad Aaron. I was told a reason why it was bad :roll: I thought it was what I typed. :oops: Wonder if they meant that water isn't really h2o, with chlorine & chloramines.... in the water. Or if the water to ice to water holds there state, its a different water make up going in compared to the tank water. My bad, there was a reason. :lol: Now I will have to find the bugger that told me. :lol: Frenchy Quote Link to comment Share on other sites More sharing options...
Afrikan Posted January 18, 2007 Report Share Posted January 18, 2007 I haven't had to do either the fan thing or the ice thing, but gee this thread is interesting Quote Link to comment Share on other sites More sharing options...
davidb Posted January 18, 2007 Report Share Posted January 18, 2007 don't leave your fan on overnight... I woke up this morning and realised I had accidentally left the fan on... without the mH running and no heater the temp had got down to 23.... not very good news... hope my xenia recovers... Luckily I didn't have any expensive corals... I hate to think what temp It was at at 4 in the morning! Quote Link to comment Share on other sites More sharing options...
Afrikan Posted January 18, 2007 Report Share Posted January 18, 2007 I used to do the ice bottle thing for my show rabbits... in the summer I would put one in each hutch.. for them to lay against to keep cool. I think if it came to fish, I would use a fan.. I know how time consuming the bottle thing was for 32 show bunnies :lol: Wouldn't want to go back to filling and refilling and argggggggggggh :lol: And the freezer space just gets eaten up! Quote Link to comment Share on other sites More sharing options...
herefishiefishie Posted January 19, 2007 Report Share Posted January 19, 2007 :roll: at David, thats it give Mystic an inch...she will take a mile :lol: {jok} Mesh.... :-? could always drop the water level of the tank by 5 to 10cm. Frenchy Quote Link to comment Share on other sites More sharing options...
Freakyfish Posted January 19, 2007 Report Share Posted January 19, 2007 Of course the Ice wont make the tank to cold Mystic Actually it wont even make the tank cold at all How hot does your tank get Mystic? How much ice do you add? What temp. does it drop to? How big is the tank? Also Jacko yeah Im not quite as good as you in explaining how exactly somethings work I just know what works and what doesnt Brad Quote Link to comment Share on other sites More sharing options...
herefishiefishie Posted January 19, 2007 Report Share Posted January 19, 2007 Just to add, this topic has been on The qld cichlid forum here. I think you have to be a member to read the thread. Here is a snippet from a guy been keeping fish longer than I have been alive, he tested a couple of theories. For those people who are skeptical about a fan over the water, I can assure you they work much better than an airconditioner. Below are some examples. Saltwater tank with Metal Hallide. No fan, no aircon- Room Temp 26deg tank 30deg Aircon all day - room temp 28 tank 29 Fan all day - Room Temp 30 tank 26. Airconditioners make very little difference unless left on 24hrs per day. A fan will lower the water temperature by 1 degree in 1 hour, try it. Theo http://www.qldcichlid.com/modules.php?name=Forums Frenchy Quote Link to comment Share on other sites More sharing options...
Robert Smith Posted January 22, 2007 Report Share Posted January 22, 2007 Jacko, Although your theory is correct (disturbing the surface of water makes it evaporate more quickly) I think the dominant effect here is the removal of the humid air from above the tank. So in muggy tropical Qld the effect of a fan will be less than in dry Wellington at the height of summer where the humidity is low and the temperature is in the mid 30's for weeks.* You can calculate the rate of evaporation from a tank of water through the following equations: m1 = A.(Xs-X).(25+19.V) where: m1 = water evaporated (kg) A = area of the tank surface (m2) Xs = saturated air humidity (kg/kg) X = actual air humidity (kg/kg) V = velocity of air (m/s) And that can give you the temperature change in the water through: dT = (H.m1)/(c.m2) where: H = evaporation heat of water (2500 kJ/kg) m1 = water evaporated (kg) from above c = specific heat of water (4.186 kJ/kg/degC) m2 = total mass of the water in the tank (kg) So assuming: - A 100L tank 30 cm wide x 85 cm long x 40 cm high. Then the area (A) = 0.3 x 0.85 = 0.255m2 and the mass (m2) is 100kg; - The tank water is 30 degC, giving Xs = 0.0271 kg/kg; - The room temperature of 30 degC and humidity of about 70%RH, giving X = 0.0189 kg/kg; - A fan pushing air over the surface at 2m/s (not especially fast, it sounds like it could be as high as 6m/s for high velocity domestic fans); You get: m1 = 0.255 x (0.0271 - 0.0189) x (25 + 19 x 2) = 0.132 Kg/Hr dT = (2500 x 0.132) / (4.186 x 100) = 0.79 degC/Hr So it seems reasonable to expect cooling of about 1 degree per hour in a smallish tank. * For anyone who's never lived in Wellington, this happens .......Oooh look a flying sow! Quote Link to comment Share on other sites More sharing options...
SpidersWeb Posted January 22, 2007 Report Share Posted January 22, 2007 Has been a good read. Thankfully I dont have to deal with keeping tanks cool, but certainly learned a lot in this thread 8) Quote Link to comment Share on other sites More sharing options...
Robert Smith Posted January 22, 2007 Report Share Posted January 22, 2007 As a quick and dirty estimate on using ice: If you use a 1.25L bottle from the freezer at -4 degC and drop it into a 100L tank, the simple estimate (dT of 1.25L = 34 degC * 1.25L/100L) gives about 0.4 degC of cooling. Quote Link to comment Share on other sites More sharing options...
Robert Smith Posted January 22, 2007 Report Share Posted January 22, 2007 Does this qualify as "Technical" yet? Quote Link to comment Share on other sites More sharing options...
jn Posted January 22, 2007 Report Share Posted January 22, 2007 Question: would the addition of ice before the tank got hot help to sufficiently prevent the heating in the first place? Rather than focussing on getting the temp down once it was already too high? Also the ice might melt a little more slowly if put in the tank while it was still an a normal temp (in anticipation on a hot day!) Quote Link to comment Share on other sites More sharing options...
SpidersWeb Posted January 22, 2007 Report Share Posted January 22, 2007 It certainly is getting very technical, but we're a way off topic. Was originally a 'how to cool my tank' thread and its turned in to a fan vs ice talk. Awesome contribution Robert, thanks heaps Perhaps a technical thread should be started with all this information. Handy if anyone is looking at running a new native tank especially. I'm gathering the consensus is a fan is a better option for tanks bigger than a standard 2 foot 60L and ice is an effective solution on the smaller tanks. Quote Link to comment Share on other sites More sharing options...
Robert Smith Posted January 22, 2007 Report Share Posted January 22, 2007 I just dropped these equations into the Technical forum with a more descriptive title Quote Link to comment Share on other sites More sharing options...
Caryl Posted January 22, 2007 Report Share Posted January 22, 2007 It had numbers in it Robert. Anything with numbers is technical :lol: Quote Link to comment Share on other sites More sharing options...
fishtv Posted January 22, 2007 Author Report Share Posted January 22, 2007 Phew, That was pretty in depth. And yes the worst of the heat wave seems to be over and the tank has dropped from 30 to 27ish so I am much happier (not to mention the fish!) Next summer I will look at setting up a fan (have to buy on first hehe) but if a hot day is coming will just stick with ice in a bottle for the last of this summer! Thanks heaps! :lol: :lol: :lol: Quote Link to comment Share on other sites More sharing options...
herefishiefishie Posted January 22, 2007 Report Share Posted January 22, 2007 Very nice Robert, well done. Great read. Yes I know it started as a my tank thread, thanks Web. I started giving view points for others too. There were others in the same boat & fishtv did say.... Does anyone else have this problem? I thought it turned into a great topic. Good to see people give different view points & ideas. I was surprised about the air con trial results. How about answering Brads question, How hot does your tank get Mystic? How much ice do you add? What temp. does it drop to? How big is the tank? Frenchy Quote Link to comment Share on other sites More sharing options...
SpidersWeb Posted January 22, 2007 Report Share Posted January 22, 2007 Tank will drop temperature overnight without ice though. Really want to test it mid-arvo. Quote Link to comment Share on other sites More sharing options...
evilknieval69 Posted January 22, 2007 Report Share Posted January 22, 2007 You alright there mystic...... :-? Quote Link to comment Share on other sites More sharing options...
evilknieval69 Posted January 22, 2007 Report Share Posted January 22, 2007 Riiiiiggghtttt Quote Link to comment Share on other sites More sharing options...
SpidersWeb Posted January 22, 2007 Report Share Posted January 22, 2007 haha oh no, this is a major personality conflict. For the most part I agree Frenchy in what you have said in regards to how this conversation has flowed, however probably best we all just drop it before it gets any more heated. You made an NZ comment in there, and I know its just out of frustration/anger, but its the start of something... just gotta relax The clear outcome is that fans are the answer to the original problem, and to tanks equal to and greater than 60L. Anyone disagree with that statement? Quote Link to comment Share on other sites More sharing options...
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