Blanket weed solution in sight?

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B.Scott
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Blanket weed solution in sight?

Post by B.Scott »

Hi Mates,
About eight or nine years back I converted my filter system from and Evolution Aqua "Answer" to a static kaldnes prefilter. My guess is that most of the older members of this board remember the conversion. It is as far as I am concerned the perfect and most economical setup I can imagine and frankly I wouldn't change a thing. At the time of the rebuild I was suffering from blanket weed (or stringy algae as out North American friends call it). But for some reason unknown to me, the moment I changed the configuration to static Kaldness the blanket week began to die back and never returned. I had always attributed this to some sort of denitrification happening within the static K but friends using similar constructions and suffering from the same trouble never seemed to get the same results I did. I speculated as much as I dared but to be truthful never really came across a valid explanation... until now.

At the core of my drum containing the static K was a mesh barrier made of stainless steel. Last summer I noticed corrosion on this mesh and replaced it with a new stainless mesh. The result was a massive explosion of blanket week inside the pond. Now corrosion of stainless steel is not something we would expect in a freshwater environment so I took a closer look at the old mesh. My examination revealed that this was in fact not stainless steel but instead a zinc mesh which I scavenged from the shop only assuming it was stainless steel.

Well to make a long story short, I obtained another sample of the zinc mesh and replaced the new section of stainless mess which I has installed when the old one was removed. The resulting reduction in blanket weed growth was noticeable within two week and by the end of the summer it was all gone!

Now you don't need to be a rocket scientist to deduce what is going on. The zinc contained within the mesh slowly leached into the system and a well established consequence of zinc in freshwater is the reduction of of algal growth. I would add that the short fuzzy algae on the side of the pond has remained and only the longer and more troublesome string algae has disappeared. That is to say the algae on the pond wall is short but in the same breath it may simply be blanket weed that is no longer able to gain any length. I cannot really say one way or the other with an in depth examination to determine the species of algae growing on the pond side and this is more or less outside my field of expertise. But when push comes to shove, I really don't care as long as the blanket weed is, and remains gone.

So the big question is; How does the presents of zinc in my water column affect the well being of my fish? We all know that heavy metals in the water are never really a good thing and are something we should try to avoid. Indeed, much of the snake oil and magic potions on the market contain a variety of nasty things, the worst of which is copper. Long exposure to copper, being cumulative, will kill your fish when used for any extended length of time. Now I know of a couple of products that contain no copper but when added to the pond produce a huge white cloud which I, as well as many others, have long speculated that they contain zinc (oxide) as their active ingredient.. They do work well at removing Blanket weed but the dose is massive and they need regular application to maintain their objective. Provided this is the road one choses to go down to deteur blanket weed, I wonder whether a very low dosage maintained over a period of years might not be preferable to adding huge concentrations at monthly intervals?

Once again, I do not have any sort of measurement of the zinc concentrations withing my pond water. This would be the ideal way to go and should anyone with to analyze samples of my water to determine this i would be glad to send them to you. The best I can do is give a rough indication of the amount of metal actually exposed to my pond and the length of time it was exposed for.

The piece of mesh I used had a weight of about 350 gr when new. The flow rate was approx. 9 m3 / hr and the total water volume 13.5 m3. Waterreplacement was in the order of 4 m3 / week. The weight of the old mesh was around 280 gr after a 7-8 year exposure. Depending on how techical you wish to get and perhaps trying to determine to ratio of lost metal and the addtional weight of the oxcides involved this information might be next to useless. But to just over simplify things we can roughly state that 70 grams of zinc was enough to treat 14 tons of water with a high refresh rate for well over half a decade. I might add that as far as my fish are concerned, in all that time I have lost but a single fish due to a swim bladder infection and all other fish are healthy individuals with sizes that vary from 58 to 75 cm and ages from 6 to 16 years.

So my question is; For those unable to controle stringy algae by natural methods and who are forced to resort to chemical controls, How much of a chance do we take using zinc in low constant applications as compared to other methods?
Cheers
B.Scott
Here a sample of the stamped zink mesh with AA batery for scale
Here a sample of the stamped zink mesh with AA batery for scale
IMG_1087.JPG (1.86 MiB) Viewed 21445 times
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estanque_koi
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Re: Blanket weed solution in sight?

Post by estanque_koi »

Hi Scott,
I have been busy this breeding season and have not visited the forum in months. But today I read your post. I recall your previous post concerning blanket weed control after your Answer to Static K1 filter mod. Now, I find extremely interesting your new observations and your hypothesis about leaching zinc oxide as the controlling factor of b. weed growth.
Frankly, I am surprised that nobody has said anything about it.
B.Scott
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Re: Blanket weed solution in sight?

Post by B.Scott »

Hi Diego,
Nice to hear from you again. Yes almost all the koi boards are suffering in attendance, not just this one.
With regards to the zinc oxide issue; there are many products out there which I suspect rely on zinc oxide as an algaecide. The one that come to mind foremost is Cloverleaf Blanket weed Answer.. But I am willing to bet that if you compared the amount of a single recommended dose of this product that is would exceed the amount that my pond was exposed to over a period of several years. I know from personal experience that the prescribed amount is a massive overkill compared to the effective amount actually needed. I have tried it in the distant past and achieved shocking results with only 20% of the dose they suggest.
But as I said above, if you can get bye without an additive than this should be the preferred course of action. But for those of us who suffered badly from blanket weed, frustration can run very high indeed. I considered quitting the hobby at one point because the stringy algae in my pond was so bad. The amount of cost and energy I expended in trying to get ride of it was huge. I cannot describe how happy I was when I was rid of it.
I am still unable to say what it was that triggered stringy algae to grow so profusely in my pond and not at all in another pond down the road with the same water as I have. I believe this would be a true breakthrough. I suspect that there will never be a definitive answer and the true reason will due to a combination of a number of different factors and not something that can be attributed to a single cause. If only it was that simple. (sigh)

B.Scott
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estanque_koi
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Re: Blanket weed solution in sight?

Post by estanque_koi »

Hi Scott,
what is somewhat puzzling to me is that you state a high rate of water changes, was it something like 5000 liters per week?
And your pond was around 13000 to 15000 liters? If that is correct my guess is that the concentration of Zinc in the water must be very low indeed.
My question is if that high water turnover of 5 tons of new water added each week was already your routine when you had the explosive growth of blanket weed?
I mean, was the change to static K1 with the "non stainless" steel mesh the only thing that changed in your system?
Whenever I had some spare time I'd like do do some experiments, I believe it could be very interesting.
B.Scott
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Re: Blanket weed solution in sight?

Post by B.Scott »

Diego,
I have never found that the rate of water changing affected the blanket weed in the pond. In the beginning I changed less water than I do today but the transition didn't make any difference to weed growth. It wasn't until I added changed the filter to static K that the blanket weed sudden disappeared. I assumed the reason was the static kaldness. But it wasn't until I changed the mesh in the filter fro zinc to stainless that the truth occurred to me. But I have seen enough people change to static K and not lose any algae at all. Replacing the stainless with zinc again caused an immediate reversal and the algae. It left as quickly as it had returned Indeed my water changes vary from 20%-30% per week. This is done in twice a day for about half an hour each time. I use a timer to insure regular changes. I know 10% change out is the norm but I have found that 20%+ has never had a bad effect on the fish if nothing more than lowering the average temperature of the water slightly. In the winter I change much less, less then 3% a week.
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