Hi Bayat,

Just use CopperSulphate CuSO4 . Go head and measure the Alkalinity of your water first then apply CuSO4 at a rate of 1 % of your alkalinity.

Take care.

Dear all, thank you so much for your good answers. I have forgotten to mention that the lake contains about 2 million fish. The lake is artificial also.  

I agree with Lotfi. Don't use an unselective algal poison, which will also have impacts on snails and other invertebrates - and perhaps also fish. Your problem may be blue-greens (often worst later in the year or after periods of settled weather), so you need to check up on control of bloom-causing cyanophytes. As Prof. Aleya says, the problem is undoubtedly complex.  Julian

I can only join my colleagues. The problem is very complicated, and today can not be solved. More would like to warn young colleagues from simple solutions. Perhaps it is such simple solutions led environment to various environmental issues.

Blooming cyanobacteria associated with a high content of water of nitrogen and phosphorus and high temperatures. However, in my opinion, these factors alone caused primarily by changes in the hydrodynamics of water bodies, reducing water exchange. If you have an artificial waterbody, try to preventively increase the water exchange.

Best regards, Mikhail.

Hello Javad,

I agree with what has been said regarding the complicated nature of such a problem and there are never simple solutions. Attacking the problem with a chemical option (poisoning with copper or sequestering phosphate with ferric sulphate) has been shown repeatedly to be, at best, ineffective and almost always profoundly damaging to the ecology as a whole.

It is true, as Lofti says, that it's too complicated for an answer here, but a starting point is to take the 3-stage approach: (1) identify your nutrient sources (e.g. influent phosphate from urban discharges, high head of aquatic birds and/or fish - the latter sounds likely - or anthropogenic input of phosphate sources, such as chicken manure, in a misguided attempt to provide enrichment and food source for the fish); (2) attempt to deal with them (e.g. reduce the head of fish or birds, reduce influent source by, for example, running the source through a planted reed-bed, stop bad practices such as throwing -in fish feed) and (3) wait for the bloom to subside on its own or, in the case of cyanophytes, try to mix the scum into deeper layers with, for example, rotary helixors. Any attempt to out-compete the planktonics by establishing large stands of higher plants, marginally or sub-surface, may also help.

It has been suggested that floating aerated masses of barley straw can also help, but this is preventative (i.e. retards growth - it won't get rid of it once it's there). Ultrasound transmitters have been effective in relatively small bodies of water, but select your hardware carefully. There are also all manner of biomanipulation options involving selective fish removal within exclusion areas to encourage growth of grazing zooplankton, but there are whole books on this subject.

Cheers,

Richard

Hi Lotfi,

I wholly agree - sediment P release has always been the issue which confounds attempts at a short-term solution in these circumstances.

Cheers,

Richard

Nitrate and phosphate removal is mandatory. But liming gives good result through algal crash

Thanks researchers, these valuable informations are cleared my doubts too. Thanks to Javed.

I agree with Abhijit Mitra and another measure a week after liming, is to introduce a large mass of Daphnids/Zooplankton to add predatory pressure to the remaining algal bloom and enforce a top down control to the ecological problem. Perturbing the lakes pH will certainly limit the Phosphate availability but one should check the water parameters before applying any chemical agent to the waterbody.

hi

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