I analyzed my water, and here are the results:
Total Alkalinity 184 ppm
Total Hardness 1180 ppm
HCO3- 206 ppm
K+ 11 ppm
Na+ 145 ppm
EC 3.7 dS/m
pH 7.41 -
I am very glad to read any comments on this water results regarding aquaponics (Nil tilapia and lettuce). I am wondering if my pH (7.41) doesn’t drop below 7, how is it possible then, to add Ca(calcium) and K (Potassium) for the plants well being.
I have no answers for you but I am curious as to what you are using to test alkalinity and K
HCO3- Mild base or bicarbonate- The most common salt of the bicarbonate ion is sodium bicarbonate, NaHCO3, which is commonly known as baking soda. When heated or exposed to an acid such as acetic acid (vinegar), sodium bicarbonate releases carbon dioxide. The same will happen to limestone when you do the vinegar test for stone composition
Na+ is a sodium ion, which needs assistance to cross the lipid layer as it is polar. It can do this either through Na+ ion channels, and also through carrier proteins, such as the Na+ H+ exchange protein. I do hope your water is dechlorinated as this ion coming into contact with CL will produce sodium chloride also known in its solid form as table salt. With high enough concentrations you can damage your fishs gills and kill your plants.
Now with this in mind and your pH being 7.41, I am assuming that you are utilizing the media base growing system and have recieved a load of gravel containing limestone. The acid in your water though-be-it mild is dissolving the limestone and defusing it into your water. With limestone you will have one heck of a time keeping the pH down as whenever you add a base, the pH will decrease for a time and more of the limestone will eventually dissolve back into the water and the process repetes again.
I suggest that you search out a source of quartzite or LECA or scoria or hydroton, all are pH nutral. I know this sounds like a pain in the (well you know) but you will be happier in the long run.