Is my aeration system cooling off my pond?

Question

I wish I would have found your website back when I started this expensive but great adventure.  I have been reading your pond information for the last hour and a half, learning so much, and knowledge I wish I would have known in the beginning.
 
Question, everyone said our pond water would get very hot this summer and should expect fish kill.  Well, it stayed very cool, almost to the point the kids didn't want to swim in it.  Reading your response, do you think some of it was due to the location of the stone diffuser, and since it stayed this cool, should I move it back to the lowest spot again in the summer.
 
Also, in the past month while fishing we started reeling in some algae (slimy green, long matted horse hair type).  Not a whole lot, but defiantly want to control it.  I was surprised due to the aeration system, lack of or no trees around, and the pond is maintained every day.  We have a blue Aquashade dye, anacharis plants, and the pond has stayed super clean on the top, so I was surprised to see the algae forming late in the year.  I treated half the pond yesterday with a product called Symmety from Lake Restoration, Inc.  This product contains copper and after reading your article maybe this wasn't the product to use.  We have not added any type of artificial "good bacteria".
 
Anything you would recommend here with winter around the corner? This is going to be the first winter for our new pond.  We are located and hour east of Denver, Colorado and have pretty mild winters.

Our pond is approx a 1/4 acre, (100 x 130) and is 14' deep on one end and steadily raises up to the shallow end.  A 40 ft x 40 ft island sits in the shallow 1/3 It is an EPDM lined pond with a 5.2 cfm stone diffuser located in the deepest end. We are stocked with bass, bluegill, catfish and fathead minnows.

I believe we are plenty deep for the fish but after reading several articles I am wondering if I should pull my diffuser up out of the deep end to approximately a 6 foot depth.  I have read that circulating that bottom shelf of water will create colder tempters.  In this big and deep of a pond do I need to be concerned?  Any other ideals?

Answer 1

You are likely not going to have any problems being in the Colorado climate if you leave that diffuser where it is...but having a diffuser in the deepest part o the pond can be an issue so it may be a good idea to just drag the diffuser up by the airline until it is at a depth of about 1/2 your maximum depth....in this case keeping the diffuser at 7 feet would be fine.

The reason for this is that keeping the diffuser in the deep end would eliminate a thermocline, which is the stratification of the pond, where warmer waters sit at the bottom. If your diffuser is in the deep section it will continuously be pushing the war water towards the surface where it will cool off at the surface and return below in a cycle that will start to "super cool" your water which can cause harm to fish.

It is rare that this will happen in a big pond  even if you are pushing 5.2 CFM in a single diffuser because even this will circulate a whole lot of water it won't have the same impact as in a smaller pond. By a big pond I mean something over a fifth of an acre.

To prevent fish kills in small ponds a small air bubbler will work to keep a hole in the ice as would a sump pump pumping water towards the surface. In larger ponds the larger deicer system works well at keeping a large hole open in the ice which is sometimes desired for duck hunters.

Of course...the risk an danger of over-chilling your pond is remote and this is a "worst-case" scenario and likely wouldn't happen in your pond with the species you are keeping  but it wouldn't hurt to just haul the diffuser to a shallower place.

Your pond may have stayed cool due to the placement of the diffuser and the capacity of your aeration/mixing system. Normally an aeration system should circulate the entire volume of the pond on a fairly rapid schedule...in small ponds we try and circulate the volume of the pond every few hours...in larger ponds it isn't always possible...but an efficient air stone diffuser can circulate several thousand gallons per minute so that sort of mixing is completely possible.

The deeper your diffuser is the more you will be able to warm up the water temperature according to the ambient air temperature. In mid summer if your air temperature is 80 degrees F then you should be able to raise the pond water temperature within 5 degrees of that with the proper movement of cold water towards the surface.

Any slimy algae like that should be treated with natural bacteria. I use dry or liquids depending on the season...it's a cheap and effective way to knock down the algae! Copper based products can have their place but in most ponds any sort of harsh copper product can create a viscous cycle where you need to add more and more of the product to keep the algae away.

Using a natural bacteria is more of a long-term strategy...the bacteria eats nutrients that cause algae and improves depth and reduces muck. Using sch bacteria will not have a dramatic killing effect on algae but over time it will create a more balanced Eco-system so I have found it works best in a long-term strategy of the ponds  I deal with.

You may want to look at an end of season "shock treatment" of natural bacteria. There are some extremely potent liquid bacterial products for ponds that help consume organic material in the Autumn and they even work under the ice. Normally we do a treatment near the end of October and a follow-up two weeks later at which point we leave the pond alone until spring.

I hope this helps!
 
Let me know by email if you ever have any other questions regarding the care and maintenance of your pond in the Summer.