Hi fellow fish fanatics, hope you all had a Merry Christmas.

I've had my vertex double disk airstaion going since mid November in my 20 foot deep 1/2 acre dugout that flooded in 2010 to become a 6 acre pond with maximum depths in the flooded region being 8 feet.

I set up the airstation this year in 10 feet of water within my dugout and about 20 feet from the spoil pile from the dugout. Aeration opened up a nice 45 foot wide hole in the ice which provided lots of open water for a nice distance over the dugout.

Unknowingly the hose froze up to my airstation last week and come the weekend about 4 inches of clear ice had formed where the water had been open. Upon checking this area out I was disappointed to find 4 dead 3-4 inch long perch in the shallows above the spoil pile and adjacent to the much deeper water of the dugout. I am hoping that the deeper water hasn't been depleted of d.o. but am at a loss as to why these fish wouldn't seek refuge there? What have your experiences been in this type of situation?

My plans include acquiring a d.o. tester so that I can monitor my water, any particular brand/model preferred that doesn't cost a small fortune?

Fortunately I got my airstation going and installed a second unit for good measure. Now I need to keep a closer eye on them during the week.

Thanks for any advice you can provide!

Frozen air lines are hard to deal with. Maybe describe how your airline runs to the diffuser. Is it burried? How far until it goes into the ice? Where did you find the freeze up?

I doubt they died of oxygen depletion ~ the ice was clear so sunlight could get into the pond for photosynthesis and the ice wasn't there for very long.
You can disconnect the airline at the compressor and pour some alcohol down the airline ~ that will melt the blockage. Is there a dip in the line where condensation can settle and freeze?

I had a airline freeze up on me recently but it was because I shut the compressor off and apparently moisture froze up in the air line. Or as Bill Cody tells me sometimes the check valves don't work as they should.

Fish of most all or all sizes do not know or realize where to seek refuge. They only know what is around them and 'assume' everything is the same elsewhere.

The first 100 feet of hose leading from my garage to the pond is above ground and had a couple of low spots where condensation had accumulated. It was easy to unhook and drag it into my basement to thaw out. Seeing as I installed the unit after the ice formed, the remainder of the hose (80 feet) is resting on the ice prior to entering the pond.

Fortunately last winter this line never froze all winter. Maybe I'll periodically add a little gasline antifreeze to it to prevent another freezeup.

My biggest concern was with the dead fish, especially being so small. My fears were that if tiny perch had succumbed then the larger fish, particulary my 2 1/2- 3 1/2 pound rainbow trout, would surely be toast.

Thanks for your input Folks.

By your description, I'm assuming that the compressor is in the garage?

Use Isopropyl alcohol for anit-icing, not gasoline anti freeze.

But apparently they can learn to find the better oxygenated water according to someone I know that used to manage catfish ponds in Mississippi. He said when they cranked up the PTO's at night before things got really critical, you could actually see the wakes in the water of the catfish heading for the area of the PTO. And these "ponds" were up to 20 acres!

Of course you have to survive a D.O. crash to learn right?

Fish can sense O2 levels and move to the best area.

Please explain how a fish and by what physiological means can 'sense' a slightly higher DO concentration of say 1 or 2mg/L that is say 80-100ft away or in the case of 20 acres on the other side of the pond 600-900 ft away. I missed that part in animal physiology class.

I understand the CC after frequent or occassional association could 'learn' or recognize that when the PTO is running the DO is always higher near the characteristic sound and associated current (probably mostly sound); a Pavlov's dog sort of association. But if the DO happens to be just slightly higher in a cove or on one side of the pond compared to say a side that has had rotenone treatment or heavy organic decay and DO is depleating how does a fish know which way to swim toward higher DO? How do they "sense" which way to go to get out of the low DO before they die? Which is what I think happened to the few small YP that died in the example above (SK-love2fish). I think those small YP got caught in a small "pocket" or zone of low DO. Plus the longer the fish is in dangerously low DO they become more and more disoriented as shown by my observations. The more disoriented they become the more irratic their overall behavior becomes including swimming and most often it appears to me then all swimming is in random directions and not directed toward the areas with higher DO.

Instinctively fish when in low DO will move toward the surface where usually slighly higher DO occurs due to experiences of usually slightly higher DO from the air-water-atmosphere interface. But I do not understand how a fish would know or "sense" to swim right, left, straight ahead or at a 55 degree angle toward higher DO on the other side of the pond.

Bill I think it has to do with the air in fish pellets.

Sorry couldn't resist.

Is it possible when they sense dropping D.O., they start moving to find higher D.O., and when they sense the slightest increase due to diffusion, they move in that direction?

BTW did you purposely create a partmanteau, which is combining two works to create a new one? Froze X Hose = Foze

Okay - I can accept a "searching behavior" when DO gets stressful.
Good one about air in pellets. I deserved that. But do you think the air in floating fish pellets has a high DO??? The pellets are probably packed so tight that it squeezes all the DO out of the air!!!!

How many times do I have to tell you Bill, there's no air in them there pellets!

Okay you "got" me again. It's the chicken feathers in the pellets that makes them float - I forgot that important point.
PS: Go to bed Baird - it's your bed time, you need to rest your brain!

I heard once that catfish whiskers are sophisticated and sensitive enough that if one whisker sensed a more pronounced scent than the other, the catfish would move that direction. This gradient is similar to a game of "Marco, Polo", contributing to a searching behavior. Could fish also seek out a positive oxygen gradient in this manner?

From what I saw in one pond last year that had a winterkill, I tend to agree with Bill.

10"-12" HSB's had a 98% mortality rate, while 2# RBT only had a 70% mortality rate. I thought HSB's would survive lower DO than RBT.

I could very well be wrong, but I think the RBT were in slightly cooler water than the HSB's and that water had slightly more DO, that's why they survived. I believe it was a short duration DO crash.

They weren't being fed, so they couldn't get any O2 from the pellets either....

That's right Essup, the compressor is in the garage.
There is about a 5 foot drop in elevation between the garage and the pond which I believe contributes to keeping the hose from freezing up most of the time.

I'll be sure to get some isopropyl alcohol for future use.
Thanks for the info!

There's gotta be a dip in the line somewhere that let a puddle of condensate form.

If you want an automatic anti-freeze up system that detects a blockage and dispenses alcohol into the line, look here:
http://www.koenderswindmills.com/Koenders_Windmills_Freeze.html

IIRC they are located in Canada.

I've had good luck with the anti-freeze system I installed two years ago. I haven't had to do anything but add antifreeze since then. It's similar to the Koenders unit shown in one of the previous threads, except it doesn't have a pressure gaurge, which would be a nice feature.

GGB

I have an air pellet gun, does that count? .177 caliber