hi everyone , i used the EC meter to prepare 10ds/m saline solution , and i found formula to how to calculate the ds/m that is EC*800 for preparing 1 ds/m .so now based one this formula i should add 400 g of NaCl for 10ds/m but when I prepar i used lower this amount of nacl for 10ds/ , so does any one suggest me which one way should i follow . follow the EC meter or this formula . thanks in advance . all the best