Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Need Help Identifying

Fairly new pond here. It was dug last spring. The only fish in there are minnows. I tested the alkalinity, it was low early this year. I added some lime and it seemed to have helped because my ph climbed from 6 to 7 in about 4 weeks. This past week it’s been very nice here in northern Ohio. The pollen is very high. I suspect this could be pollen. When I spray it, it breaks apart and turns a muddy brown color. This pond is used for drinking water, I’d like to keep this thing very clear. I tested it, no phosphate, no ammonia, no nitrates and decent PH 6-7. Alkalinity is around 40. This is odd to me because I’m used to this pond being VERY clear. A few weeks ago I could literally see 7’ deep to the bottom. Now it’s around 18” of clarity and very brown. One of my pictures shows how clear this pond usually is, it’s at least five deep in that picture. Any help or insight is appreciated. Thank you all.

We do have expert "identifiers" on the forum, but I am not one of them! Nevertheless, I will give it a shot.

It looks like something organic to me. Either phytoplankton (plants) or zooplankton (animals). Can you grab two bottles of material at the same time, and put one in your house that only gets some indirect sunlight and put the other in a very dark closet or cabinet? If it is phytoplankton, it should die in a few days in the bottle deprived of light.

Another option (as you say) is just some windblown pollen. It may have been yellowish when it blew in, but is now oxidizing to a brown color or may even be creating a coating of periphyton.

All of the processes I described above are 100% natural and expected in a pond. If you started with a municipal pool filled with chlorinated water as your drinking water supply, it would still develop algae after the chlorine content declined sufficiently.

In my (non-expert) opinion, none of that constitutes a problem, other than it might affect the taste of your water a few weeks of the year.

However, there is actually one dangerous scenario you do need to study. Cyanobacteria algae growing in your pond can create toxicity in your drinking water, or even to pets or livestock using the pond.

If you suspect cyanobacteria, I do NOT know if you can test for that yourself, or need to send it to a lab. Hopefully, some of our actual experts will drop into your thread.

Congrats on your new pond! Water clarity going from 7' to 18" is fairly normal once the water warms and the sunlight increases - stimulating the living organisms in your pond.

Thank you very much for the information. I am having a local company out next week to test the water. We shall see what it comes back with

That dark crap looks like dead organic particulates in various stages of decay. It floats probably because of the gases produced from the decay. Ponds are always, constantly in the process of change depending on what is in the pond and what is getting into the pond that eventually results in some sort of growth that usually dies and decomposes. Ponds are composed of numerous internal complex interacting systems same as the human body - always changing. Right now your pond appears to be puking from too much of something.

your pond appears to be puking from too much of something.

A wonderful highly scientific and descriptive statement. You nailed it!

So then if the highly scientific theory that it’s puking something bad up, some good bacteria could help?

Strange enough I had four sacks of barley straw in the pond, I took them out because they looked pretty bad and nasty, once I did that it started to clear. Then I put them back in and it started to come back, I took them back out and what do ya know? It’s cleared up.

I’m guessing I left them in the pond for too long and they ended up having the reverse effect that I wanted from it.

All of the organic processes in ponds get VERY complicated very quickly.

One of the mechanisms by which adding barley straw to a pond inhibits some algae growth is based on the production of humic acid from the late-stage decomposition of the straw. Further, humic acid does tend to turn things brown.

If that is the current operating mechanism, then the humic acid MAY be killing a bit of algae and as the dead algae is decomposing it creates gas bubbles causing it to float. (And the humic acid and/or decomposition is turning it brown.)

When you said the pond was "clearing" with the barley straw out, did you mean the scum floating on the surface or the secchi disk reading was getting deeper?

If the latter, then my speculation is wrong. Or, some unrelated change has occurred contemporaneously in your pond.

Here is a basic primer on barley straw.


Barley Straw for Algae Control

Thank you FishinRod, Both we’re happening. Depth visibility improved and the floating scum was clearing out.