Transferred from. RE: got stock tank heater, help Posted by drh1 z4 VT (My Page) on Wed, Feb 21, 07 at 19:52 Air Exchange In Your Pond 101 Judging by several of the comments there is a bit of confusion on what is occurring with gas exchange into/out of your pond. I apologize for the length of this - feel free to not bother to read it (except for Rule #1). Rule # 1: If you have a pond and youve been doing something that works for you and youÂre happy with it....forget everything else and stick with it. Do not read any further. All other Rules: The following are "things" that influence the RATE at which a gas will go into or out of solution: a.) Water temperature - the colder the water the more of a gas can be held in solution... and therefore the higher the saturation concentration (commonly referred to as HenryÂs Law and is also dependent on the concentration of the gas in the atmosphere as well as the temperature); the colder temperatures will decrease .... somewhat.... the RATE at which a gas will diffuse through the water and into the air or from the air into the water. b.) Turbulence and mixing. The RATE at which a gas moves into or out of the water is controlled, in general, by a very thin film of water molecules right at the surface of the water (commonly referred to as FickÂs Single Film Model  as one example). The thicker this film the slower the RATE at which the gas can go into or out of solution. The more mixing or turbulence you provide the thinner the film. Therefore, if we arenÂt getting enough gas (oxygen, for example) into the pond we mix it, let it cascade down a waterfall, use a bubbler.. all of which cause the water to mix and "refresh" the surface and reducing that limiting liquid film thickness. The same applies to getting gases out of solution. c.) Surface area. Often people assume that this is the only variable or parameter that influences gas going into or coming out of solution. While it is a very significant factor it is not the only thing that is relevant. Obviously more surface area is better but there is a point of diminishing returns when there is so much surface area that there is little significant increase in the RATE of gas transport. When we use a stock tank heater or a pond heater the surface area is obviously the amount of clear water surface that we see. However, when using a bubbler the surface area is NOT the size of the hole from which the gas is exiting but rather the TOTAL surface area of each and every bubble that is produced under water. So if your bubbler is putting out 4 liters of air per minute, with an average bubble diameter of say an 1/8 inch you will be producing a little over 80 square feet of surface area each minute. The finer the bubble, the more the surface area. This is why bubblers are much more effective in promoting gas exchange than something that opens up a 2 foot or 3 foot hole in your ice (~9 - 27 square feet). So what size hole should one have? There is no specific answer for this nor can there really be one. It depends. If you have "a lot" of fish in your pond then youÂll need more surface area for gas exchange than if you have one comet in your 2000 gallon, lake. Secondly, water temperature also rears its ugly head again. As a general rule of thumb (which means itÂs not accurate at all!!) biological activity doubles for every 10 degree C change in water temperature. So if your pond is at 2 degrees C versus 12 degrees C then the amount of wastes produced and consumed will be significantly lower than for the higher temperature. This means that if you intend to keep your pond a nice, toasty 45F all winter with your pond heater, immersion heater, solar heater, backyard barbecue grill, etc. then youÂre going to need a significantly larger amount of surface area than the person that lets the pond sit close to freezing. The assumption that your fish huddle around your heater holding their fins out for the warmth is a bit too much anthropomorphizing! Being of New England stock and heritage means that my DNA is such that I donÂt like to part with my ÂLincolnsÂ... and I mean the one cent variety. ThatÂs why I use a bubbler here in zone 4. My pond is pretty close to 3000 gallons (as a guesstimate) with a depth of only 3 feet. IÂve had ice as thick as 18" on it (about 2 years ago if memory serves me correctly). Essentially all of my fish survive and appear to be well each spring. Sometimes there are a few less of the smaller comets but I happen to know for a fact that the Koi will munch on them over the winter. All of this with nothing more than a 4.5 watt aquarium air pump! My electric bill never sees the difference. The URL below should give you access to a pdf file that was mentioned by Horton...it describes what I use for a bubbler system. I would not recommend it for small ponds in zone 4. ThereÂs even more that we could discuss but IÂve obviously babbled on long enough. ÂDavid

Our pond is dirt based - no liner. It was a former cellar under a small building but kept filling with water. The previous owner filled it up with rocks. We tore down the building, rearranged the rocks and let Mother nature take over. The pond filled with water. Our gutter water runs into the pond to help keep it full. We have an overflow running under our driveway and down a hill to keep the pond from overflowing. Fish and one now large water lily are doing well. A filtration system was added 5 years after the original set up. Muck is a problem so a few years ago we removed the fish and sucked out all that we could. Instead of using small rocks again, we replaced them with various sizes of field stone. We have 30+ fish and they seem to thrive. We never feed them. Our situation is unique. This pond somehow links underneath our patio as the fish winter under our patio. They swim through the rocks and re-emerge in the Spring. We have no idea what is under our patio. . how much water is held. . how deep. .but we know when the pond gets low the fish disappear. I do add tap water during the summer months as the pond does evaporate rather quickly. It's not likely the chlorine will hurt the fish as I add it in gradually over a few days. Sometimes I put dechlor in but usually I am careful not to add too much. Our tap water has never hurt the fish that are in there. In fact, as the water is added, the fish swim underneath - possibly enjoying the cooling hose water. This pond is approximately 10' x 10' and 2' deep.

Hey Sandy (nice to see the name of someone I recognize!) No I feed my fish twice a day in a small feeding ring. My father and sister in law both have fish (lots of them in what I consider very small ponds) that they don't feed. Only reason I feed the fish is that my pond is so big with so many places for them to hide that unless I tempt them to come up to the feeding ring I never even catch sight of them (and then get anxious that they have died) and so like to see them at least once a day just to be sure they are okay! At any rate I am just baffled by the foam - there is virtually no pond debris to speak of (that I can find anyhow - no leaves, acorns, decaying plant matter etc.) but I live under a dense canopy of mature hardwood trees and we have just completed our rather horrible yearly gypsy moth cycle and not to be too gross about this but when the gypsy moths are up in the trees munching on the leaves it virtually rains gypsy moth feces for a few weeks (it is so bad that at night when the feces is dropping out of the trees it hits the leaves of the trees and makes a patter so loud that you think it is actually raining!) At any rate, whilst I can blow this crap off of the decks and sweep the paths etc. I cannot control it falling into the pond (where it dissolves as soon as it hits the water) so now I'm wondering if this crap falling from the sky could be the culprit? I mean it's not like I've never had any foam before, but I've never had this much and for this long. Guess I'll just increase my filtration and continue the daily water changes... I would so love to drain the pond and scrub it and re-fill but I can't catch the fish...sigh...how does one catch such small fish in a large pond anyhow???

I think I am still a big kid as well. I love going on the swings at the playground and when the little fair comes to Lotherton Hall I go into the teacups as they are like little waltzers for children. Luckily I have the grandchildren to make it look 'normal'. As to our other problem we have now signed up with another company and have asked Streamline to pass over our details which of course they have not so now we have had to ask the new host to get the details for us but I don't understand all that. Sonny deals with everything. He is trying to recreate my website but of course all the work that I had done will have to be started again and it took ages to do. Tomorrow I am going to Citizens advice to see how we stand in getting some of our money back so I will keep you informed. I can't believe it really and just hope that people won't have deserted us but will look again in a week or so and find us back up and running. Kew Gardens is so expensive for it's entrance fee. I thought Castle Howard was dear at about £7 last time. They will soon price themselves out of ordinary peoples pockets. I know they have wages to pay etc but it puts us off going. I am lucky that at Lotherton Hall and Temple Newsam estate it is free. You pay to go round the house and at Lotherton you pay £3.50 parking but I have a yearly ticket which pays for itself if you go more often than 4 times a year.It also entitles me a free visit into the house every time I go. It is lovely there with a deer park, bird garden, pond and formal gardens and a playground for the children. Both houses are about £3.00 entrance fee and at Temple newsam there is a rare breed farm, lakes, rose garden, woodland walks and open land. Capability Brown made the gardens at the price of £2000 I think and had originally put in more lakes in the plans but they only did 2. I think they ran out of money.