Pond Boss Forums AERATION Systems questions Lift pump H2O circulation vs. diffused aeration?

We are in the process of designing a new 9 acre bass pond on our Central California property. Pond shape will be "L" shape. There will be small islands in the pond to act as wind breaks as we get high winds (to 40 mph ) on occasion and need to protect the wind exposed 10' tall levees on 4:1 slopes. Max. depth will be approx. 12' and average depth approx. 8'. Well water available as well as electrical power at the pond. Fish stocked will include copper nose bluegill and feed trained F1 largemouth. Three fish feeders will be feeding the fish year round so there will definitely be nutrient loading in the pond. Summer temps for three months of the year are over 100 degrees daily and winter 3 months we have lows in the mid 30's at night with 50's as daily temps.

I have already obtained a price and design from Vertex for a Air4 XLS / 4 diffuser aeration system. Pond turnover rate with this system will be 1.39 times per day.

Some of the other property owners want to investigate the use of a lift pump to pull water from one end of the pond at depth and then pipe it to the opposite end to shallow water. The goal is circulating the water. I have seen this done in golf courses. I realize that best would have the water coming down a stream and or water fall to allow maximum air contact with this water.

In your expert opinions is there any benefits to a lift pump circulation over a diffused air system for a pond this size?Would this be a more effective way to circulate a pond of this size? Our kw $ rate for off peak periods runs around $.11 per kw hour and $.18 and $.43 per hour during daylight peak periods. The plan on either the Vertex or a lift pump circulation system would run the systems for 12 hours per day (6 P.M. to 6 A.M.) for 10 months per year which would keep our annual electricty bills well under $ 1,000 annually. I need to provide info on costs versus efficiency of both systems to make some management / financial desicions to present. I am familiar with the diffused air system as we already have a Air 2 / 1/2 hp Vertex system on a small 2.5 acre pond we have. My question relates to a lift pump circulation system in lieu of diffused air system. Thanks in advance for your ideas on this!

Dave

Hi DaveB ~ I'm giving your post a little "bump". I have no experience what so ever with lift pump circulation, but I can't imagine it being very effective in maintaining dissolved oxygen through out the water column of a 9 acre lake. I would stick with what you know works. Hopefully someone with some experience will chime in....

David here is part of a post from the Archives maybe you should read. Mr. Bruce has a great post in there called Aeration Simplified. Here is part of it below. Maybe this will help you some. I believe the part below was written by Dave in ELD and Bruce chimes in right below him again. The hole post is really good stuff!!



Great 3000th post Dr. Bruce! I am curious about the efficiency of circulation versus bottom diffusers and aeration as it relates to DO throughout the entire water column. I read your previous post about DO throughout the entire column after just circulating and it caused me to consider circulation over aeration. Does circulation use more energy than aeration? Is it more effective even though it consumes more energy? Is one better for different types of fish than another? Does one effect temperature at depths more than another?

So many questions...


victor, i think yer question might highlight the biggest difference between bottom diffusers and circulators like the ones bruce, dwight, and shorty use. circulators dont affect the thermocline as radically as bottom up diffusers do.

so here's my weak attempt at a comparitive analysis, posted for the experts to shoot down.....(actually wondering if we can make a list of generalizations):

circulator - disturbs water surface more and thus fights FA growth better than bottom diffuser,
-doesnt mix water column as efficiently and leaves O2 dead spots in deepest areas of pond,
-not as effective at breaking down muck accumulation
-protects thermocline better which is most important in winter (i.e. does not completely destratify pond)
-contributes to greater evaporation rate in summer months
-on average, uses more electricity?

bottom diffuser - provides more oxygen faster to the deepest areas of pond because the mixing of the enitre water column is achieved faster,
-does not disturb water surface as much, so doesnt fight FA as well
-fights muck accumulation better
-destroys thermocline, and completely destratifies pond
-can potentially harm fish by cycling the anoxic muck up through water column and rapidly raising temps
-contributes some to evaporation during summer months, but not as much as circulator
-on average uses less electricity?

David, to calculate which will be more cost effective we will need the electric consumption of the lift pump, and how long you plan on running it.

My off the cuff answer would be that the Vertex system will be more effecient. More of the dissolved O2 gets into the water by wave action and the interaction of the water and the air than by the fine lifting bubbles themselves. If the circulation system is used, the only way to get more surface area exposed to the air would be to run it over something that breaks up and splashes the water around. I don't know what system will have less evaporation, which will be a concern during the summer months.