In another post Mr. Ted Lea said someting that was very important."Know Your Lifting Rates" I wanted to repost it here under the correct area. I know it's important and would be a geat subject for in the Archives. When it comes to an air setup how does one "Know your lifting rates"

I am sure it would be a time consuming post but if any of you pros out there would like to please explain this in more detail and laymens terms I think it would be very helpful to a lot of us that are new to the air world. Any takers?

Thanks in advance for your time as always,

I have asked Sue with Vertex to post a simplified flow chart that gives an example of various airstations at various depths with the constant being 1 cfm per disc. This chart is available at www.cleanponds.com on the home page. Link onto the 2011 catalog and scroll to page 18. Hopefully Sue can post this and save you the time.To know your lifting rate you need to work with the diffuser manufacturer or Airstation manufacturer that has taken those membranes and put them in a set configuation and has tested them. Testing can be done at various independent sites and some manufactures are now doing inhouse and or extrapolated testing.Results reported in gallons per minute are common, Once you have calculated your total gallons in your pond simply do the math. For example if we have a 1 acre pond 9 ft deep on the ave lets say we have 2.9 million gallon or 9 acre ft. If we know a station tests at 3000 gpm at 2 cfm in 9 ft of water that is 4.3 million per 24 hour , divide your 2.9 into 4.3 and you have 1.49 turns per 24hr day.Placement of station(s) will come into play with the shape of the pond.Not all difffusers are tested since they may be primarily designed for wastewater inwhich they are spaced close together on large tubes and are creating a super saturated condition.This an entirely different concept. Pond diffusers utilize the atmospheric oxygen to add oxygen to the water.Waste water diffusers are often sold for pond aeration but can be difficult to know how they are performing.Some diffusers are made specifically for bottom diffused aeration inwhich they have been tested and achieve high lifting rates with low cfm's. This will be a good starting point to get this thread started.More to come !!

Hey Ted that's good stuff right there!! Thanks for your input! I am looking forward to Sue's post and anything she can add would be great! I think this is a very overlooked topic even though alot of people have air in their ponds I think a lot of them including myself are not quite sure how much turn over we are really getting??? And if you only run your pump say 8 hours a night or 12 then how much are you getting?? If it took me 24 hours to turn my pond over 1.49 times per say then I may go from 8 hours a night to 12 if it would help a lot. Another question would be how many times do I really need to turn over my pond in a given week per say?

thanks again,

Sorry for the delay ~ I was having Photobucket issues yesterday. Here is our lifting rate for each style AirStation based on 1 CFM per disc. As Ted stated, this is a little different for each diffuser/manufacturer. [img:center][/img]

Sue thanks for that post.Note that different configurations lift different amounts.Placement of the discs in relationship to each other also vary.This is an example of 5 different airstations that show no one station or configuration fits all. A decade ago most single diffuser stations were abandoned as it was found that pairing them up led to 4 times the lift, 3 or a tri setup did not seem to add enough addition lift GPM to warrant that design over going to 4 discs if they were in at least 14 ft of water. A tri set up was not wrong just not as advantagous.RC to answer your question "would increasing your run time help a lot?"Depends on what your trying to accomplish. If enough DO to keep fish alive is the goal then you may be OK, if you want to destratify the entire water column and get the maximum amount of aerobic bacteria for maximum organic matter decomposition you might not be."How many turns needed?" Depends again on goals and age of pond,what % you are of carrying capacity etc etc.My minimum lift per day that I suggest is one,This has become for the most part an industry standard even though many bladders on the market are not tested. I have arrived at this be doing oxygen and temp checks after circulating to see what is needed to get the water column within 5-6 F from top to bottom and DO levels within 2 ppm from top to bottom.I often size additional turns if it is an older pond or in the midwest or north where 12 months of running might not be advisable. A pond that is fertilized for a bloom might get 1 turn max as to not disrupt a bloom (this has been discussed prior) I really prefer to size to aerate 24/7 to minimize the natural peak and valley that comes with the natural production and respiration. A proper system will keep the temp and do "swings" to a minimum.

One point of many good ones that Ted made is the water temperature difference between the top and bottom of the pond. If your temperature is more than 5 or 6 degrees F difference between top & bottom then that indicates DO is likely low, will soon be low, or non-existant at the bottom where the temp was measured. The greater the temp difference than 6 the more likely DO is abscent. Remember tests for DO verify this feature, but the temperature difference which is a lot simpler and cheaper to measure is a very good indication of what is probably happening with dissolved oxygen in your pond. Exceptions occur but these usually do not occur in regular 'fish' ponds/lakes. Your pond is probably not unique in this regard. NOTE: this applies to mid summer conditions and not during winter or cold seasons.

Very nice. Thanks ya'll for getting involved in this I think it's a great topic that gets overlooked a lot!

So if the above rates on the graph are based on 1 CFM per disc can I assume using this same 2 disc setup (Vertex I Believe) above at a rate of 2 CFM per disc at 10 feet would this double my lifting ability from 3400 to 6800 GPM? Barring my pump can put out 4 cfm Or am I wrong in thinking that?

Thanks,

Cant assume that as it is not straight line math , 4 cfm tests out at 5200 GPM. 4 cfm is also the max for a 2 disc Vertex unit.A single disc from Vertex has a operating range of min .5 and max 2 cfm. So when you see discs that have upwards of 3-4 cfm per disc as the top end or a wide operating range I would be suspect that they are a med slit that may actually lift less at the top end of the range as they start to produce larger bubbles that lift less, That would be an example of when more (air) equals less (lift)Those discs are very popular in wastewater applications as they foul less with wide operating ranges and larger slits.Most waste water units do not need a flow control device since they are mounted level on supply tubes. Onn a pond bottom where you might not be perfectly level the air can go to the high side of the disc without FlowControl which is built into these discs.

Ok thanks Ted for that information very nice to know!!