My pond what to do

Troutman

Interesting question Rup and to be honest I dont know at what depth the fish go to or how much oxygen there is down there. They always seem to survive the summers in the dam though. I live in a fairly windy area and the water in the dam generally gets a good turnover to break up any stratification that occurs on a hot day so I guess this may assist in taking oxygen to the depths.
In the Marron ponds I use an air lift system during the night to provide oxygen as the ponds are farmed intensively where as the dam is only
lightly stocked with fish.

twintragics

slade, aquasonic have some excellent pond aeration devices. Google them and click aeration on their products menu. It is a 2mb download. The things that are relevant to you are on pages 18,19,20. Air is key if you intend to run some sort of small commercial setup. Aquasonic are the main players in the commercial fish recirc system in Australia. (I have absolutely no affiliation, they just have tons of good stuff imo.)

KudaPucat

yeah I've seen their catalogue... nice gear

creative1

I think there might be an issue with trout as I think the pond site is very close to the estuary, as such may have flooding risk.

slade

Hi Troutman
I would like to get a few trout to throw in with the mix maybee even some redfin just to see what happens, can I get some from you

Daniel

RupertofOZ wrote:

Do you try and lift your deep water Troutman?

At that depth wouldn't it be oxygen depleted???

i would say you probably would't want to lift the deep water up, as thermoclines would form, and you wouldn't want to mix the deep cool water with the upper hot water (if you are trying to keep cool water fish alive in hot areas that is...) but not sure how the 02 would diffuse between the thermoclines...

KudaPucat

they can come up to the hot to breathe then go relax again down deep, can't they? Do fish have the ability to reason cold is good, but breathing better?

Troutman

In my dam I have had trout come and take food from the surface when water temps there have been 28c. They hang around for a while feeding then disappear again down to the cool depths. I think that generally the oxygen supply at depth (3m+) where the water is cooler must be sufficient for fish survival as most lakes in southern australia would be experiencing surface water temps above 24c at present.

Quote:

i would say you probably would't want to lift the deep water up, as thermoclines would form

Daniel the opposite is in fact the case. By lifting the cooler water up from the bottom you break up the thermoclines as the cool water is mixed with the warm. Obviously you wouldnt want to do it if you were farming a cool water species but its common practice with things like marron or perch as you also add oxygen to the water at the same time.

KudaPucat

I think Daniel was attempting to state that thermoclines would form (as I believe they would) and that lifting the water would be a bad thing.

KP paraphasing Daniel wrote:

don't lift the water as you wouldn't want to mix the water between the thermoclines that would otherwise form

Troutman

I gotta start to read a little slower.
I saw the would't as a would'nt.
Maybe I need to get some glasses!!

KudaPucat

Troutman wrote:

I gotta start to read a little slower.
I saw the would't as a would'nt.
Maybe I need to get some glasses!!

I have to type slower, I made the same error, I have corrected. he is suggesting not to destroy the thermoclines.

Troutman

Back on topic.
Slade I wouldnt put any Redfin in your pond if I was you. The redfin will breed in there and in such numbers that they will eat out your food supply with the end result being a heap of stunted fish. At least with the other species you have control of what numbers you have in the pond.

RupertofOZ

Ummm... perhaps with trout, you may not want to mix the water, but from what I've read for most other aquaculture species and operations (particularly dams) it is common practice to lift deep water.....

One reason is that thermoclines form naturally and just as naturally can collapse and "turnover"....

When this occurs the turnover initially almost completely inverts the layers resulting in a rapid (albeit shortlived, except in very still conditions) deprivation of oxygen... as the lower layer is oxygen deplete and then a rapid algael bloom caused by semi-decomposed deritus, zooplankton etc suddenly becoming exposed to sunlight.

Sadly this depletes almost any remaining oxygen in the inverted layer before any significant mixing can take place.... Wind and/or human intervention can alleviate the situation.

Quote:

From Wiki....
Thermoclines can also be observed in relatively shallow lakes. In colder climates, this leads to a phenomenon called turnover. During the summer, warm water, which is less dense, will sit on top of colder, denser water that sinks to the bottom; with a thermocline separating them.

Because the warm water is also exposed to the sun during the day, a stable system exists, and very little mixing of warm water and cold water occurs. One result of this stability is that as the summer wears on, there is less and less oxygen below the thermocline, as the water below the thermocline never circulates to the surface. As winter approaches, the temperature of the surface water will also drop until it approaches 4 °C (39 °F), which is the temperature at which water is densest. 4 °C is, generally speaking, the temperature of the water below a thermocline.

When the entire body of water is at or close to 4 °C, 'fall turnover' begins - the thermocline disappears, (or, to say a different way, it reaches the surface) and the water from the bottom of the lake can mix freely with the water from the top. This process is aided by wind or any other process that agitates the water.

dandm

Slade, this looks great!
We have recently been browsing the forum to get ideas and advice... and your system has given us an idea! We have a farm dam (small though) but it dries up in summer (related to the water table).

What did you use to line your pond, and was it very expensive? Do you filter or aerate or anything like that?

....we are now thinking of digging ours a bit deeper and lining it so we can keep water in it all year round...grow fish...
dandm

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My pond what to do

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