It is hard to understand your question. EDTA is used to stabilise PH in larval culture of shrimps and thus maintain diatom blooms, but not for "hardness" of water in culture ponds (as far as I know, but I may be wrong). Please be more precise with your question.
Andreas Laggis... Thanks for your valuable response. Here in India Vannamei farmers are believing that the EDTA is reducing water hardness, maybe due to its metal chelating property. According to my knowledge, metal chelating property is found at higher pH environment. Personally I have checked with lab results. Before and after EDTA application there is no change in the hardness of water.
But the farmers still believe that the application of EDTA, brings some changes in animal behaviour like... Reducing moulting stress and subsequently maintaining growth increment.
An additional information is they are using EDTA 5 kg on the moulting days... When the water hardness is more than 6500ppm.
sanjeeb kumar pradhan , thank you.
Hardness result will not change . . . Application of EDTA may act on shrimp . . Relieving from hard water stress for time being. This statement I am recording here because . . Some farmer using EDTA at moulting days, and see some positive results like moulting and recovery.
The mechanism I don't know. I have started this discussion to know more field results from various region , on EDTA application and positive outcomes. I won't prefer to use EDTA . . . now I may try it. . With various dosage to see the positive in using it.
garuku govindarao . . Ya. . . scientifically high pH is required for EDTA reaction with solutes in water.
So aquaculture ponds usually having the between 7.8 - 8.2 at morning time.
I want to know that, is there any positive results based stories available in the field.
Using EDTA in the hard pond water, brings some positive signs
( elieving stress due to water hardness) in the shrimp behaviour.
Thanks for your inputs and interest.
To my knowledge, EDTA will soften the water upto a certain extent. In a hard water environment, shrimp outer shell will get harden and face the difficulty to moult. Hence, by applying EDTA, hard water gets soften and in turn helps in soften shell and moulting process. This might be the reason farmers will apply EDTA in thier ponds during the moulting period.