Finally I manage to test my tank water. It's about 7 the alkalinity may go up, will check again next week. Grow beds are new so its unstable.
If alkaline goes up then I will add vinegar like distilled malt vinegar or apple cider, can't be harmful to fish and plant since its organic.
Test kit above, requires 5 ml of tank water with 5 drop of test fluid. A color chart is provided to check pH value, its idiot proof. I use syringe to get the exact amount of water into the test tube.
Will get the ammonia and nitrite test kit next.
BTW Someone suggested to pour Guinness into the grow beds, he say Guinness have a lot of iron this may help provide iron to the plants.
Anyone can confirm this... the Irish may have something up their sleeve with aquaponics I guess. Interesting suggestion, will the fish get drunk ... :) I wonder.
I was in Dublin for a few years of my life, its a beautiful place and very friendly people.