I thought I would provide an update on my HBG pond, post treatment with a fluridone product. (Whitecap). To recap, this pond is 2/3 acre, max depth of 11', average depth of approx 4'.
As this pond was built in the early seventies as a swimming only BOW, it had a large pea gravel beach, with a vast area of shallow water. The pondweed coverage was extensive, to put it mildly. Over the last two summers', I spent a lot of time and money trying to control the pondweed, and it's partner in crime, Filamentous algae. The Diquat, and Cutrine Plus flowed freely, but the effects were always short-lived. I could knock it down, but not out. There are 5 huge GC in this pond, they loved the grass my weedeater scattered over the water's surface, but never put a dent in the pondweed.
This past winter, I decided that something different had to be done. The usual recommendation in this scenario is to try and lessen the excessive nutrient load in the pond, usually by some sort of watershed filtration, the planting of beneficial and controllable plants to better utilize the existing nutrients, or both.
Sounds easy enough, but in practice I don't think many of us could afford to alter our pond's watershed to the degree that would be required to alleviate the problem. I certainly couldn't. I liked the beneficial plants idea, but would rather get the existing plant growth under control first.
After much deliberation, I decided to go with a Fluridone product. This is not really a poison as much as carotene inhibitor. In basic terms it "starves" the plant to death. As such, it is very slow acting. It is also non-discriminate. Good plants, bad plants, Fluridone makes no distinction, (or almost none, there are some plants that are resistant.)
The trick to making this stuff work, is to maintain a specific level, in ppm, in your water. This means that a heavy rain could wash your product right out the overflow, while the influx of fresh water dilutes the remaining concentration to an ineffective level. Not very appealing for a chemical that cost around $20-$25 an OUNCE. Yep, an ounce. Fortunately, it doesn't take all that much to treat an average pond.
I ordered the product, (Whitecap), and waited through the wettest, rainiest Spring in recent memory. Finally, on Saturday, May 7th, I caught a break. The pond level was at normal pool, and the forecast looked relatively dry for the upcoming week. I went for it. I closed off the primary spillpipe, added the fluridone, (by boat), and crossed my fingers. My aerator was running twelve hours, at night.
After two weeks I noticed that the grass at the water's edge was beginning to turn white, as were a handful of cattails that I normally keep mowed down, but had decided to leave as an experiment.
Then came the rain. I sweated bullets as I watched the water rise 10". It was no where near going over the emergency spillway, but I knew my precious 45 ppm minimum concentration was being put to the test. After a week of nightly aeration I figured whatever damage that could be done, was done. I opened the spillpipe and brought the water to normal pool. All of the grass that was covered by the higher water level, turned white. I took that as a sign that the product was, at least, still partially viable.
Four weeks in, and the pondweed was hurting. It was turning brown, and starting to fall down, or collapse. At least in shallower water. Interestingly, this is also when my new Weedrazor and rake arrived. Through their use, I was able to sample the weeds out in deeper water. they were much greener, which initially puzzled me. They were showing definite signs of distress, just at a slower rate.
Then, last Sunday, 5 weeks after treatment, I could no longer see any pondweed in water shallower than about 3', All that was left was a dirty, silty residue on the bottom. The water was beautiful, with about 6' visibility. Good for this area. Wearing a mask and snorkel, I was able to explore deeper water, and found the pondweed still there, but all brown and crumbly. I surmise that the deeper stands of weeds are slower to react to the fluridone, due to the more limited transmission of sunlight into the depths. That's just a guess on my part, however.
What is most certainly not a guess, is the FA problem. It loves it's new, competition free environment. I sprayed the edges with Cutrine Plus Sunday morning. By afternoon, it was gone.
Then came Tuesday, two days ago. I went over to feed about 6:00 pm, the water had gone from beautiful, to something that looked like strong iced tea. The fish wouldn't eat, which is unheard of from my HBG. Visibility had dropped to 24". Fearing the worst, I switched the aerator to run 24/7.
Wednesday morning was much the same. No fish piping.
Tonight, Thursday, the water looks a little better. Visibility is 30" The fish fed some, but still not normal. My other, untreated and un-aerated ponds have also darkened considerably, but not as much as the HBG pond. I'm sure there are particulates in the water from the decaying weeds and algae, and the aeration is probably stirring it up. Combine that with the normal, summertime water staining, and that may account for some of the discoloration. I'm not sure if a bloom would establish in this treated water? In addition, A couple weeks earlier I had begun to notice schools of fry in the pond. Now, with the weeds gone, I don't see nearly as many. I'm hoping that the decreased cover has resulted in increased predation by my HBG. That would help explain their diminished appetite. The situation will be watched closely.
In summary, the Whitecap did what I was told it would do. My experience suggests' that it starts off slowly, then accelerates toward the end. 16 ounces of this product absolutely took care of my pondweed problem, but for how long? I am sure it will come back, but perhaps I have a chance to get some beneficial plants established in the meantime, to help use the nutrients.
Also, I am concerned about a possible fishkill, due to a lack of any oxygen providing plants. I will move my diffusers to shallow water for the winter, to try and offset their disappearance.
Would I do it again? it's too soon to say. I'll revisit this question a year from now.
Sorry about the long post.
