depth vs area ... ?

[Terri]

Pond depth and climatic considerations, where you live would dictate depth - wintering zones need depth for fish survival... but we usually do not discuss or consider the area that depth covers.

What would you think would be sufficant sqft area of the deepest part of the pond for over wintering, thinking that the pond is moderately stocked with varying sizes(from young to adult)?

[Jackie Ramo]

Interesting question Terri. I took all the big rocks out of the bottom as soon as the fish didn't git there anymore. They've overwintered for 2 years now, 2 bad winters but this year???? its always a question. I'd not have thought more than the fish need for space since the like to be together anyway...

Certainly in my pond there is only room for the fish and now since I don't have rocks to remove, fish need to go when they are either too big or too many to fit in the deepest space.

[Dewi]

Very interesting,my deepest area is 2x1 metres, which is at 5' this year it has been forecast that it will be one of the coldest winters on record.

I have read somewhere that fish in my climate need at least 1metre but nothing has been said of how much area,

I do know that there is very little movement, so would they require great areas?

Also if they are closer together will this have the same effect as humans huddling together??

[Jackie Ramo]

Mine is almost 5 feet here and they have overwintered ok so far. Last pond was 4 ft and they overwintered there as well. -30C last year.... you won't see that Dewi

[Busy B]

Well now that you started the topic, expand on your thought processes :grin:

[Terri]

Well ok Busy :-P

The place to start would be the adult size your fish will reach, which we also use to determine total gallons need for "x" amount of koi for stocking purposes. For example, a 5000 gallon pond with 10 koi should have a minimum of 6' x 10' sqft area for winter resting at the bottom. Part of the reason is earth to liner(or concrete) contact and the depth of the pond(hopefully minimum 5' depth). The earth is warmer during winter at that depth(being below the frostline) and should maintain the lower level of water at 39F or a few degrees higher(depends on depth). The larger the sqft area the more heat transfered to the bottom of the pond, and for the koi this makes survival through winter easier to cope with, especially those of us who have 6 months or more of freezing temps. Koi do not "huddle" to maintain warmth, as we know their body temp is regulated(majority) by their environment, the water.

While young fish(6 to 10") may do ok through the the season with, say, 3' x 5' bottom area those same koi in a couple of years double if not triple in size. That 3' x 5' area would be rather crampt with 22" to 28" koi, survival rate is greatly diminished through winter into spring. Why..? The larger the fish the greater demand for resources(O2 & heat primarily). Having a larger surface area is terrific, but it does not help the fish during winter when it's 90% covered with 12" to 24" of ice and they are left to a "small room" at the bottom of the pond. The volume of pond water is reduced for those in a winter climate, in some cases by more than half.

Any of this make sense?

This is only a part of the whole picture, but as I mentioned before, it doesn't seem to be something that is discussed. Surface area & pond depth are the topics we tend to think about when designing/building a pond. If you look at most ponds, the surface area is most often quite larger an area than the deepest area, where the fish do tend to spend quite a bit of time.

[Busy B]

Makes sense..reminds me of some ponds I see where the bottom of the pond is the deepest part but small and narrow.

Handy info for when I fine tune the expansion. I can only hope that the earth gives off enough heat!

What's your normal lowest temp in your area?

With us...if we don't get early snow cover and it gets cold, the frost goes into the ground deep. Not any way around that I guess.

[Jackie Ramo]

snow and ice are great isulators keeping the really cold temps at bay for both the pond and the garden. Ice not being the best insulator for the garden... :roll: but it does fine for the pond.

I've never had the depths of ice Terri has experience in her pond in my own pond even though we live reasonably close together. I do think the rocks in my pond make a difference, certainly of all the ponds of the koi club, mine is first to open in the spring and last to ice over, even before I started running it through the winter. The sun hits the rocks and that rock heats the one underneath it... not scientific but logical to me. The deepest I've ever had ice was 6 inches and that was one very cold winter.

As for water temp, I don't have Ian's toy but I have measured the bottom and the top temp and have not found any difference but admit the thermometer may not have been actually resting on the bottom. Its broken now so no testing the theory.

[Busy B]

Stole this from Brett on the NI board but good info...would this info factor in to early spring die offs?

Also...the discussion was about die off in a mud pond.



Deep pond?

It takes a deep pond with a fairly small surface area to valume ratio to create a "winter turnover" which would normally occur at a much lower temp than 65 degrees.

During the warm weather a thermocline, usually two such, forms in the water, a dividing line between two depths of water that do not mix.

The "organic rain" of substances that enter the pond, leaves, grass, debris, fish waste, etc. falls through the thermocline to the bottom and decomposes. All of the oxygen below the lowest cline will not only become depleted, but the water will obtain an oxygen deficit that could be expressed as a negative oxygen content.

Say 1/3 of the water in the pond has a negative 12 ppm (large deficit) and the rest has 6 ppm. When they mix the net resutl is 0 ppm and the fish all die.

But, this happens when the surface water reaches a temp of about 42 degrees, is inundated with hail or other ice, or is mixed by a storm or other reason.

The aftermath of oxygen depletion leaves allmost all the fish up on the bank as they tried to find some oxygenated water near the surface.

Any crawfish or other motile water life will have crawled out of the water in order to breathe and will be seen around the edges of the pond.

You can have an oxygen depletion in a driving rainstorm. Sometimes it is the accumulation of cold rain on the surface that "breaks through" to the bottom that brings up depleted water to the surface as the cold rain displaces it. This would be the most likely theory in this case.

In summer weather, just being cloudy and raining without displacing bottom water is enough to create a depletion due to lack of sunlight. I've seen fish die of oxygen depletion in the pouring rain. Rainfall doesn't create enough oxygen to overcome other factors depleting it in many cases.

Other things that might cause a problem....
Mosquito spray (especially if aerially applied), other bug killers from overspray next door perhaps.

Toxic algal bloom or algea bloom that creates a high CO2 condition in the water.

Hydrogen sulfide, tri-halo methane, sulfer dioxide, and a host of other toxic gasses can form on the bottom then be released into the water if it is stirred. Release of hydrogen sulfide in small amounts can kill all the fish in the pond. This is another effect of an anaerobic bottom condition.

To fix it....

Pump the pond dry, allow it to air out, remove bottom sedimants down to hard bottom, apply hydrated lime to the bottom, about 500 pounds per acre, install destratification/aeration device, refill and restock. Brett

[Merlin]

Wow that was certainly a lot to take in !wow! , good post though. :)

OK now remind me again what is this stuff you lot keep calling Snow :lol: . We are lucky in the South of the UK that our winters are quite mild compared to others areas of the country, occassionaly we see a bit of the white stuff, but it soon goes. As to Ice even in a bad winter it rarely gets past 1" thick, and easerly dealt with. :)

[Terri]

Thanks for "bragging" Merlin ;)

Busy, certianly Bretts information could play a part in our ponds seasonally - spring die-off can be due to several reasons, most times a combination of degraded waterQ, rapid thaw(or refreeze) and (related to)O2 levels. Good information, mostly linked to earthen ponds(different animal compared to backyard ponds), but interesting to know. Thanks for posting that :grin:

[Rembrandt]

That was interesting! "Brett" from Brett's Fish Farm in Danburry? Pam got some of her fish from him. I guess we take it for granted here in SE Tx with our near tropical winters. Run heaters at night and A/C during the day. Heck, we think it is cold when the temp gets down to 60F. Pam pretty much wears shorts year round. I will admit that in the winter, I will put on a long sleeve shirt but usually roll the cuffs up.

Merlin, that white stuff I think is snow. I've seen it on tv before. It is hard for me to immagine ice 12" thick on a pond but I saw many posts last year of ponds covered with ice and snow. Brrrrrrrrrrrrrr!!

Pam freezes gallon jugs of water and places them in the pond just to keep the water from getting too hot. We are fortunate in that we don't have to deal with the ice and frost stuff here. At least on a regular basis as I remember one year we had a freak ice storm that downed numerous power lines, broke pipes, and tons of branches. With the recent hurricane that just came through, our tree populations have been considerably thinned.

Still trudging through the stacks of claims here so I better get back to work.
That was an interesting article however.

I do have a question however: when you do water tests, should the water be taken from the bottom, middle, or from the top? I think we just take ours from near the top. I just always assumed it was "mixed".

Rembrandt

[Jackie Ramo]

Rem, glad to see you, we've missed you both.

In our size ponds it doesn't really matter but in the big mud ponds it may. I usually take mine from a few inches down knowing the water is well circulated.

[Busy B]

I'll send you some snow Rem and Merlin so you can experience it !bonk :-P tho it may be a little 'watered' down before it gets there:smile:

Definately more of an article for mud ponds altho good reasoning for cleaning up the debris in the bottom of the pond before winter hits. If I'm reading it right, the waste depletes oxygen and as it decomposes, adds the toxic gasses.

The part I don't get is :


In summer weather, just being cloudy and raining without displacing bottom water is enough to create a depletion due to lack of sunlight. I've seen fish die of oxygen depletion in the pouring rain. Rainfall doesn't create enough oxygen to overcome other factors depleting it in many cases.

How does the sunlight factor in?

[Jackie Ramo]

Not sure about the sunlight factor but rain doesn't usually hold a lot of oxygen and the breaking of the water's surface when it hit would not be enough to oxygenate the water deeper down... so the stressed fish could still die even in the rain. Perhaps the algae would be giving off co2 instead of oxygen in cloudy weather as it does at night???? where is that Brady when you need him

[Busy B]

That makes sense..maybe it's more for the warm season climates than I have. Colder water holds more oxygen right? I never have to worry about putting frozen milk jugs into my pond. :grin:

Still thinking...wouldn't the rain create turbulance on the surface which would add oxygen...yeah Brett...come visit.

Unless it was a driving rainstorm that stirred the layers too much...ahhh I'm so
:-?

[Jackie Ramo]

If the lack of oxygen is down deep than the rain will not add any, even in a heavy rain storm the surface aggitation would still be pretty shallow. I don't think these ponds he is speaking of have any circulation. When you think of it it pretty silly to put fish into that type of pond but maybe keifer has some input.