Pond Boss Forums AERATION Systems questions Diffuser depth?

Greetings;
I've heard talk against placing diffusers on the bottom and instead at about the 2/3 depth range. Anybody hear of this and have any input? Seams to me you would lose moving the water that you should be targeting.

Thanks;

Joe

Were they referring to placing it at that depth for the winter or summer?

I placed mine on bottom, turned it on and forgot about it. I read posts where there should be a gradual start-up process but I didn't bother. While there may be good reason for all of that, I sometimes think that we can overcompliate somewhat simple processes......and I'm probably the worse when it comes to certain aspects of my pond.

Diffuser start up has a lot to do with the pond depth, season of the year, and water quality within the pond. Start up time and duration sometimes makes very little difference AND sometimes a really big difference. It all depends.

I got this info off a manufacturers site while researching systems. They state bottom placement will over-heat a pond in the summer and over-cool in the winter. I understand the concept of super-cooling a pond, but the over-heating one kind of baffles me.

Joe G,

It's the same concept. In the winter, you are taking the denser, warmer water on the bottom and mixing it with the cooler water near the surface; hence, super cooling. In the summer, you are taking the denser, cooler water from the bottom and mixing it with the warmer water near the surface.

You might ask how can this be possible to be mixing denser water that is warmer in the winter than the surface but then taking denser, cooler water in the summer and mixing with the surface. Logic would suggest that have denser/warmer and denser/cooler doesn't add up. But remember, water is a unique compound. It is most dense at 39 degrees. This is why ice floats at 32 degrees. Most compunds become most dense at their solid state, but not water. It gets denser the cooler it becomes until it reaches it's max density at about 39 F and then becomes less dense again below 39 F.

If you have warm water species do not be concerned about overheating your water. If you have cool water species and the population is not high fish such as SMB and YP will also be fine unless your pond is very shallow and you are over circulating for which you can easily monitor during summer heat. Cold water types can easily get overheated with bottom diffused aeration if not done correctly.As far as diffuser placement in deep areas that can depend on the age and organic load of the pond prior to aeration. If for example you have a small area of very deep water and the pond is perhaps 10 plus years old and heavy organics this can act as a nutrient sink and collection point for negative things. Then consider staying out of that area unless you are willing to start the aeration up very slowly. There are general guidelines for most startup procedures but often is necessary to custom tailor a startup depending on several factors based on your pond specifics. I have old deep ponds take months to expel negative gasses where the pond owner wanted the stations on the bottom from the start vs slowy moving them deeper or slowly starting the system.Seems the more mature fish are the first ones to belly up when a system is started improperly.Bill and Shawn gave you great information ! ( and Makoclay perhaps got luckey)

I'm shocked that a manufacturer would put such a blanket statement out there like that. Diffuser depth totally depends on the pond, the type of fish, the region, the goals, etc....

Thanks for all the input; as with many questions there are no cut and dry answers. I'm installing a new system in a pond that is starting it's 4th year with warm-water fish (LMB/BG). Deepest spot is 10' with an average of 5' over about a 3/4 acre pond. Plan is to place one diffuser in the 10' area and one 150' away into the shallower end. I'll do this in March when the water temps start to change over. Pump capacity is 3-4.5 CFM at 30 PSI - depth of my pond no issue here. Does anybody see any issues with going directly on the bottom with the diffusers and letting the windmill system run full-time (wind alloeing) - as I am not near the pond - No suplemental feeding is in place.

Thanks
Joe

Joe, I dont see a problem with that at all.The windmill in itself will give you varied aeration unless you have electric assist.You also perhaps have airstones or large pore membranes and the lift wont be to the point of over circulation most of the year. HOWEVER I would consider just shutting off the deep one about Thanksgiving and turn it back on the end of March or first week of April in your neck of the woods.A simple way to do this is just T in a dump valve and let the deep one exhaust off to the air when you dont want deep circulation.This is providing this mill has two independent pressure lines off the compressor.

Ted - Great feedback, that's just the type of info I was looking for. I have a 2-way valve at the windmill, so shutting off the deep stone isn't a problem. To the bottom they go........

Joe