Its ok if someone else is asking about algae problem on this thread. I will sooner or later face that as well.

Anyway, further update on my tank...

About another 6 neon tetras were added to the tank about a week ago.

Then 2 green tetras have just died !!! One 4 days ago and another yesterday. Not sure what is happening, but water was still quite green so did a quick 1/3 change of water. Added 15 drops of PMDD(thks for correction). Could the green tetra be weaker as compared to the rest of the fishes ?

Did a test on my ph and KH. My ph shows about close to Akaline level (i think its about 6.8 ph) and my KH is about 5/6 drops (meaning the water is quite soft right ?). I don't know if the reading is correct as the ph tester, I have it was bought almost 4 years. Does it still works ? I think my water is not acidic enough right... so need to make it more acidic.

My Co2 indicator indicated a little short on Co2...so have increase a bit more to about 4 bps from 3 to 4 bps.

Do you think I need to start buying NO tester to see how much nitrate is in the water pullated by the fishes ? Not sure which one I should also get the No2 or No3.

Anyway, recommendation and suggestions pls ?