Tomorrow (the day after Thanksgiving) I'm going to treat my trout pond with Potassium Permanganate to see if I can clear the water by killing the phytoplankton that is coloring the pond a Coca-cola brown. In the nine years I've had this trout pond I've never seen this brown of water. It's not a plankton die off that is normal this time of year as there there typically isn't much phyotoplankton in the pond anyway due to it being flow through most of the year. Bill Cody has identified a heavy bloom (27 inches of clarity) of probably the genus Ochromonas which is a "yellow/green" algae and had been associated with fish kills although not proven to be the culprit.
I've had problems with the brook trout in the pond this fall with stress, which has led to some fish succumbing to bacterial disease -- most likely an Aeromonas or Pseudomonas variety. It's also not uncommon with brook trout vs. brown or rainbow trout.
Antibiotic treated feed got a so so response, however, in all honestly I should have a test done to determine exactly what bacteria I'm dealing with, and which antibiotic is most effective to treat it. Unfortunately there are no fish certified vets in Indiana except those at Purdue University, and it's been problematic to get a live fish to the university several hours away. I was set up to go one morning with our "good vehicle" complete with aerated tank, but I wasn't able to collect a specimen.
Anyway, it's possible that if I'm dealing with a gram negative bacteria the PP could knock that back along with killing the phytoplankton that is coloring the water a dark brown, which shows no signs of leaving. See photo below. Also if parasites are involved the PP may deal with them also. I don't have much to lose as there are only about 30 or so fish left compared to the 100 I planted last fall. I'm looking at this as a learning experience, and if it helps so much the better.
There are two ways to go about this: One is to apply 2 mg/l of PP to the pond (2.7 lbs. per acre/foot), and if the water stays pink for 8 to 12 hours you're good. If it turns brown before that there was enough organic matter in the pond to neutralize the PP before it became effective. Of course on the other hand adding too much can not only waste the chemical, but also be detrimental to the fish in the pond if one over does it.
A better method is to determine "Potassium Permanganate Demand" depending on the organic load of the water by using samples of water, and calculating how much one would need depending on the volume of the pond. Here's how it's done and how I did it, which by the way I got the information here:
http://edis.ifas.ufl.edu/fa032First as per the PDF I made a stock solution of 1 gm. of Potassium Permanganate per liter (1000 ml) of distilled water. I didn't have any beakers or anything to measure milliliters in so I used a quart canning jar that was marked up to 800 ml and poured that into a cutoff 2 liter clear pop container. I measured another 200 ml out and added that to the 800 ml to make 1000 ml or 1 liter.
Here is 1 liter (1000 ml) of the distilled water before adding the PP:
Here is the same distilled water with 1 gram of PP added to make the stock solution.
I transferred stock solution to a canning jar (the canning jar wasn't quite 1 liter), as I needed the pop container to add 1 liter of pond water to.
Here's a 1 liter (1000 ml) sample of pond water (on the right) before adding 1 ml of stock solution. The tape marks the liter mark. One waits for 15 minutes and if it turns brown in the 15 minutes it's not enough. If it stays pink one multiplies the ml added by two and this is the minimum concentration added to the pond.
Here is it is after adding the 1 ml of stock solution:
Here is is after 15 minutes. It has turned brown so the 1 ml added means 2 mg/l application to the pond is not enough.
I next tried adding 2 ml to another liter of pond water and it stayed pink which means 4 mg/l pond treatment is enough.
However I decided to add 1.5 ml to see if 3.0 mg/l was enough as I don't want to add more of the chemical than I have to. It turned out the 1.5 added stayed pink so 3.0 mg/l treatment to the pond is enough so i will go with that.
2.7 lbs of PP is needed to make a 1 mg/l treatement per acre/foot. Since the pond is 0.5 acre feet I need to add 1.35 lbs. per mg/l. 1.35 lbs X 3.0 mg/l = 4.05 lbs. or 4 lbs. 1 oz.
Later Edit: My new fish health textbook I just got for an early Christmas says to multiply by 2.5 the ml's used instead of 2 for the mg/l treatment of the pond for bacterial issues. That makes the amount used come out to about 5 lbs. vs. the 4 lbs. 1 oz. I've got about 5 lbs. so I'll just use it all.
