they require oxygen as do other living organisms, thereby some- 

 times creating oxygen deficiencies below the level necessary to 

 maintain fish life. 



Another phenomenon which normally accompanies excessive algae 

 growth is high pH . This is brought about by exhaustion of free 

 and half-bound carbon dioxide and the formation of alkaline 

 carbonates or hydroxides. High pH (9.5-10.5) may not kill fish 

 per se, but fingerling bass and bluegills often cease growing and 

 become emaciated under the extreme conditions that bring it about. 

 The alkaline death point for fish is pH 11.0. Fish production 

 becomes reduced in the pH range 9.5 to 10.5 according to Swingle 

 (1959). 



The two most important water-bloom algae that give trouble 

 in fish ponds appear to be Microcystis and Anabaena . The former 

 causes fish ponds to take on a "muddy" appearance, while the latter 

 give off a pig-pen odor when wave action deposits scums on the 

 shores. Either dichlone (Phygon-XL) at 0.05 p. p.m., or copper 

 sulfate at 0.3 p. p.m. is recommended for their control. Recently 

 Lawrence (in a personal communication, 1960) reported that he 

 had obtained good results in the control of Microcystis by 

 suspending 0.8 - 1.0 pound copper sulfate per acre in cloth sacks. 



Lake Treatments of Water-bloom Algae 



In lakes, copper sulfate is still most widely used. In 

 Minnesota, lake treatments are made at a rate of 5 pounds per surface 

 acre. 



In Wisconsin (Mackenthun, 1958), copper sulfate applications 

 to lakes are varied according to alkalinity. Where the methyl 

 orange alkalinity is less than 50 parts per million, 0.3 p. p.m. 

 is used. Where the M.O. alkalinity is greater than 50 p. p.m., one 

 part per million is used to treat the upper two feet of surface 

 water. This is equivalent to 5.4 pounds per surface acre. 



Dragging burlap bags containing copper sulfate crystals 

 suspended from boats, is a common method of large-scale treatment. 



More efficiency is obtained in lake treatments with equipment 

 illustrated by Mackenthun, (1958), which is reproduced in Figure 2. 

 In this method, water is pumped from the lake with a pump aboard 

 a barge or platform placed across two boats fastened side by side 

 (Figure 3) or mobile trailer (Figure 4) as used by Domogalla 

 (Anonymous, 1959). The use of barges or platforms propelled by 

 an outboard motor, permits transport of larger supplies of chemicals, 

 thereby saving frequent trips to shore. On the discharge side of 

 the pump in this equipment, water is conducted to a drum and sprayed 



