How To Clean A Natural Spring Fed Pond

Prior Pragnotherse · Monday, 22 November 2021

Natual Spring fed Pond... Problems I Need help

Hello,
I'm Ola from Sweden. I just wanted to write a short introduction and say hi.

We built a pond six years ago when we build our house and it's been great. It's a semi-natural pond where we simply had a pond dug in a wet/swampish area of the yard and a spring has filled it to a nice pond. No liner or filters, just nature. We estimate that the spring changes about 15% of the water each day so We also use the pond for irrigation.

Lots of plants and reeds moved in already the first year, along with frogs and dragonflies etc. We only planted a few water lillies and other plants and the rest is just natural.

The pond is about 15x15 yards or so and close to 3 feet deep in the centre.

We introduced fish last year but they all died. Some probably during the winter and some this spring. The jury is still out on why this happened.

Here's a pic from last year (clickable for larger image):

This year, the pond is murkier than usual and there is lots of orange sludge on the surface and as muck on the bottom. So, most of my threads here in the beginning will be cries for help with various cleaning/water quality and what can be done without altering the naturalness of the pond too much.

Cheers

/Ola

P.s. Ola is a male name. I tend to get the question d.s.

The moderator Noahsnan was kind enough to copy this intro to the "mud forum" so I thought I should add some more info on the issues I have with the pond.
I know I have a high iron content in the water. It's common with all natural water sources around here. I don't know *how* much iron I have yet though. Will get a professional lab test asap.

The pond has been completly natural, apart from us digging the actual hole, for years and has matured nicely with rich flora and fauna. When we introduced wakin, koi and comets last year we also added two big airstones at the beginning of the winter to keep the water open. This worked like a charm and when the ice was gone this spring we saw about half of the fish seemingly quite happy. Then suddenly the all got ill and died within a week. (Info on another forum http://www.jb-forums.com/forums/ubbt...ue#Post138036).

In short, it seems they got some bacterial/viral infection and I'm a beginner with fish so I cannot make a correct diagnose.

What I'm wondering now is if my high iron content combined with powerful aeration has something to do with the fish dying. My theory is that during the winter, the ground froze enough to shut the spring off and snow helped dilute the water and lower the iron before I turned on the aeration. When the ground thawed this spring, more and more iron was introduced in the pond and reacting with the aeration and somehow hurting the fish? Just a wild guess and as I said, I'm a beginner at this.

The water has been quite murky this spring. More so than usual but it has not been a "black" tint as if the airstones stirs up the black muck at the bottom. It's been more of a greyish tint. Hard to describe but I know how the water looks when I disturb the bottom and this is not like that. The aeration has been turned off for a week now and the water clears up from the spring and outwards. Not as clear as it usually is though.

Finally... string algae... I haven't had more than tiny amounts of it before but this year it's loads. Maybe it's a coincidence and it's just because there was lots of growth in the pond last year and it's now fertilizing the algae but I want to link it to the iron/aeration as well (of course )

Sorry about the lenghty post and for things that may not make sense. English is not my first language so please bear with me and just ask me to clarify if something unclear.

/Ola

I was hoping someone more experienced than I might pick up on this one, no such luck yet. Strikes me that the fish load should be kept fairly low for this situation, nutrient and toxic substance buildup could be a problem. I think the fish are/were feeding algae and bacteria. If the iron in the water is clearwater (I think ferrous form) then it would consume oxygen, perhaps contributing to low dissolved oxygen. Further, high iron can load up the iron-binding proteins in animals and (presumably) fish. This can result in higher susceptibility to bacterial infections. Perhaps someone more useful will jump in. Your English, however, strikes me as quite good!

Last edited by bbriggs; 05-15-2007 at 06:57 PM. Reason: clarify post

Thank you. I used to work as a technical writer at an english-speaking company and consider myself above average in writing, for one having english as second language of course, but I know that I've lost my "edge" since I moved to a more or less all-swedish office.
We had nine tiny fish in this pond. All under four inches I would guess, maybe five. So I think that would constitue as "low load", no? At least four of them looked quite happy after the winter. Two koi and two wakin. The sudden decline in health has me quite stumped and most answers I've gotten has been admitted wild guesses. It took literally week from looking healthy to dead.

The iron level has me quite worried. I'm seeing more and more of the orange sludge now. I try to clear the surface but it's like foam and just breaks up. I have done some work around the spring this year, adding tiny waterfalls rather than just having the water running along the ground. Could this be the cause for all this iron slude I'm getting this year? I'm thinking the extra aeration/agitation of the water makes the iron react. Maybe I'm just getting a visual of the problem that has already been there? Other critters seem to thrive in the pond though and I'm told that frogs and toads are sensitive to poor water quality and we have tons of them.

Also, the bottom of the pond is really filling up with sediments this year. Any suggestion on how to clean this? I'm thinking a pump on the bottom feeding a settlement chamber and then back to the pond. Then I could move the pump a few times per season to "clear" the bottom. I want to build a second pond anyway (of course) so including a settlement chamber wouldn't be too much extra work I think. I'm afraid though that the planned stream back to the pond would aerate the water further and thus create more iron-related problems? Maybe I should just get a pondovac and vacuum it all out. Or just a pump leading to "nowhere" for that matter. I measured the water flow from the spring and it's around 1600 gallons (6000 litres) per day so the pond will be topped up quite quickly even if I go bonkers with a powerful pump. I use around 800 gallons for irrigation once or twice a week and it's hardly noticable in the water level.

[edit]Cleaned up some poor english. Some still left but hey, I'm Swedish

Last edited by ofranzen; 05-15-2007 at 09:14 PM.

By the way. The second post is a reply to my original presentation thread and when the introduction thread was copied here it tagged along and now it refuses to be deleted. It's a nice sandwich though

You don't want to avoid aeration.
Yes, aeration will add to the orange sludge, but it gets the iron out of the water - which is good.
I don't understand how the water is getting into the pond - is it seeping in from the bottom, or running in from a stream?
If its a stream, and you have sufficient topography, you can build a little dam or a little series of dams, so the water has to fall a couple of times before it hits the pond. Those dams will fill up with orange sludge, and it will be easy to vaccum it out from the little puddles before each dam.

Cleaning a mud pond is a mess. We drain ours, dry it, and then use a bulldozer to scrape out the bottom muck.
I think that would not be practical in your application.

"To bosom friend, to gracious host
To those who fall, and those who lift
To those who give, yet mark not gift
To healing, hope, and circumstance
To faith, to fate, to meetings chance"
-Bob Kublin (who I have not met)

The water enters from a spring around 2-3 feet above the surface of the pond. Here are two pictures of how it's arranged now:

The spring is just by the solitary orange rock. The steps are new this season and that's why I'm thinking that the added aeration causes all the lovely orange sludge on the surface.

I could just bury a big bucket under the last step and maybe this will catch some of the iron? should I keep several smaller steps or arrange it so it's one big drop? Or are there any other clever ways to set this up?

Draining the pond is not an option as this would ruin the other life in the water. I'm getting some kind of pole with a net to try and remove as much of the visible gunk as possible but it's not really a long term solution

We have iron in our source water and extra aeration will make it settle out. Maybe you could install a large catch basin (200 gals) on the high side for the stream to run into. Put a bottom drain in the basin with waste drain pipe to remove the sludge. Then add an air pump to the basin. A large overflow pipe from the basin would direct water down to a falls or spillway into the pond. Just a thought.

For the love of Koi
Don't Sweat the Small Stuff

Lifetime Charter Diamond Member #4 WWKC

Certified Koi Keeper (CKK)

Hi Ola,
The surrounding ground where the Spring is, is that peat?

What is the ponds depth

What trees do you have in the ponds water catchment area?

Have you measured the ph of the pond

At a guess, what percentage of the pond volume is debris, from the trees

Close to your area, what industries or facilities might be actively affecting the water table

You say you use your pond for irrigation, what are you applying the water to?

>>Also, the bottom of the pond is really filling up with sediments this year. Any suggestion on how to clean this?

On a nice warm sunny day, dredging with hooked tools, sturdy nets, removing several buckets now and then should reduce the bio load step by step so the pond goes into Winter in good shape

Regards, andy
http://www.members.aol.com/abdavisnc/swglist.html

Last edited by andrew davis; 05-16-2007 at 12:04 PM.

>>The surrounding ground where the Spring is, is that peat?
I think it is peat. It has that "bog smell" but how can I tell if it's really peat or just soaked dirt? What difference would peat do for the water?
>>What is the ponds depth
Between one and three feet.

>>What trees do you have in the ponds water catchment area?
Birch, pine and spruce mainly.

>>Have you measured the ph of the pond
I've measured it several times and it's always been around 7. I've double checked with the test strips for the hot tub and it said 7 on those too.

>>At a guess, what percentage of the pond volume is debris, from the trees
I'm not sure I understand the question but if guessing there's about four inches of debris on the bottom now. Leaves but mainly from reeds and other water plants and of course all this orange sludge.

>>Close to your area, what industries or facilities might be actively affecting the water table
No, nothing like that. We hardly even fertilize our lawn and when we do, we use less than recommended. Some of it may of course leak into the pond but I doubt it as the spring provides such a big water change.

>>You say you use your pond for irrigation, what are you applying the water to?
Mainly for the lawn but also for flower beds and for a little vegetables and potatos we grow some years.

Further details on how I should treat the incoming water is highly appreciated. Links to similar setups or maybe plans detailing how the settlement chamber should be plumbed would be great. I'm reading the d.i.y. section here but as always with my pond, the setups are not directly applicable so I'm a bit in the dark.

The peat does not seem to have bothered the pond, if the ph is 7.
With that amount of debris in the pond, there would have been a significant amount of decomposition going on through Winter. Hydrogen sulphide, methane and other goodies.

With an air pump on the go through Winter, barely putting out any oxygen in the water before it rose and broke the surface, that might have made up some for the lack of oxygen from the incoming low oxygen spring water...

However, fish don't like air pumps, the fish may well have been driven by the noise into the areas where noxious gas concentrations were 'highish'

My guess is snow blanketed the pond, long enough to destroy algaes and plant life by blotting out the light, in numbers, too...

Additionally, the air pump is likely to have circulated warm stratified lower level water to the surface, cooling the pond to temperatures koi do not like. Under 38�f and koi are headed into a danger zone. You might try measuring the temps at the bottom of the pond next Winter, when the pump is working, and when it is switched off

The combination of air pump noise, interfering with stratification, significant volume of debris, a long Winter probably left your fish in such a weakened state, the first bacterial infection that came along had little resistance...

You might check your scenario with Bill Cody, and ewest on pondboss.com, they can probably refer you to folk in Canada, who face 200 day freezes and keep trout (more fussy than koi) under sealed ice ponds. For 200 days...

Basically, it boils down to making sure the snow is swept so the plant life under the ice stays healthy, the stratification layer stable...

You might consider making a chamber to oxygenate the spring water before it goes into the pond, so the pump noise does not drive the fish to the far side of the pond. Ideally, they need to snooze quietly in the deep area in stratified water which is usually 38�f - 40�f

The red sludge may just be a red herring, of no consequence other than a benign rust mineral...

Regards, andy
http://www.members.aol.com/abdavisnc/swglist.html

Originally Posted by andrew davis

The combination of air pump noise, interfering with stratification, significant volume of debris, a long Winter probably left your fish in such a weakened state, the first bacterial infection that came along had little resistance...

That sounds spot on...
I will start by cleaning out as much old debris and sediments as possible before getting new fish this summer and of course investigate other means of (economically) keeping holes in the ice during winter. The air pump is probably way too powerful and messed up the stratification way more than necessary. Oh well, that's what you get for not being cheap

The airpump may be of use for removing the iron in the water in some sort of aeration and settlement chambers. I'm sending away a water sample on Monday so I know what levels I'm dealing with.

Thanks alot for your help.

/Ola