That's right - I remember my shubunkins used to do it when I had a pond before. My Koi all do it when the gnats are above the pond - don't do it any other time so it must be because of them. As to the blanketweed - I also have this problem, but I keep a long stick handy and keep twizzling the blanketweed round that - it's amazing how much is there. I always leave the blanketweed I have got out by the pond for a day so that any tiny creatures in there can get back to the pond. :D
RandyRos, to be on the safe side, buy yourself a test kit for NITRITE. Nitrite is poisonous to Koi, probably all fish come to that. Tell-tale signs of too much Nitrite are the fish jumping clear of the water. The kit only costs a few £'s and should be readily available somewhere near you. Cheers...freddy.
one of my contracts suffers from very bad blanketweed in a substantial circular stone fountain feature, a combination of chemical and pulling out controls it but despite my best eforts I cant eradicate the awful stuff.
No fish, just a 40' circular feature with around 2' of water depth and a central fountain. Ive tried barleys straw extract, also tried a sachet based algaecide, both work with limited success, the base of the feature is lined with cobbles so its very difficult to remove all traces of weed manually. At the moment, I pull out the worst by hand fortnightly. Its a real shame though as up to two years ago the water was perfect.
saddly there are many treatments and equaly many different pond combinations eg size x depth x numbers of/type of fish x same with plants x water types (high ph,phosphates+) which is why none work every time in every pool sorry if answer is not what you want.