Pond Boss Forums GENERAL QUESTIONS Help Drained pond has metallic orange scum on soil.

We are in the process of draining/renovating our spring fed pond. The water level is down to just inches. It is currently iced over pretty well, but there is a metallic orange sheen on the soil and frozen in the ice. It is mostly located to the thinner South (creek) side. Curious if anyone knows the following:
1. What causes this?
2. Is this a problem?
3. How can I correct this?

I do not know, but always thought it was iron bacteria like one can get in a well.

Yep RAH is right. Also some odds and ends leeching from soil. Nothing to worry about.

If it was not a problem before then I would not worry. Agree with RAH & Cecil - iron most likely.

Agreed on the iron. We get that in some creek beds around our area where there is acid mine runoff that gets into the watershed. Have you checked the pH of the water? I'd just be curious to see if you have acidic conditions.

Todd,

Actually iron is one of the most common elements on the planet. Not isolated to acidic conditions. Heck my well water can jump as high as 8.7 with intense aeration, and still have iron in it!

I think it is important to note that it is insoluble iron that causes the red color. My understanding is that iron bacteria convert a soluble form to an insoluble form. pH will also affect solubility, but I do not know the particulars.

RAH,

That may be the case with the iron bacteria but the iron in itself in ground water will create a red color once it oxidizes and it's exposed to oxygen. Interestingly my homemade iron filter for my RAS' goes from a red to a light green and then clear as it filters out the iron.

Looks like we are both thinking correctly. Water with dissolved iron is clear, but oxidation causes it to become insoluble.

http://www.idph.state.il.us/envhealth/factsheets/ironFS.htm

Yep I am very very familiar with that using ground water with about 2.5 mg/l iron for my previous trout pond and my indoor RAS tanks. Not sure if I posted this before, but here is how I get gin clear water in 24 hours for make up water for my recirculating aquaculture tanks. When refilling I use a garden hose nozzle to aerate the water. I just let it do it's thing overnight and I have gin clear water the next day. The more it's used the better it works as the iron particles attach themselves to the iron precipitate coating on the filter material.





Water gets pumped from one barrel to the other via 30 watt mag drive submersible pump and is pulled back through filter material via a gravity operated 'u-tube" siphon.

Why remove the iron? The iron can be stressful on the fish depending on the species and size of the fish as it is sharp edged and can irritate their gills. Trout are the most sensitive as are smaller fish with finer gill filaments.

In larger volumes of water at low flow rates it's not an issue as the iron precipitate gets diluted and settles. However in my 100,000 gallon trout pond at 45 gpm it still created a opague green color as it was settled and diluted somewhat but not completely.

Thanks to all of you for answering so quickly. We are new to the pond world and have much to learn. This Pond Boss Forum seems to have quite a bit of information. I'll be sure to post soon on my next question! Thanks Again.

You might have intrest in this manual/guide read it before you refill the pond.
http://pdacrsp.oregonstate.edu/pubs/pondsoil.pdf