Ph meter

I always use lemon, but if I could calculate it, I would use citric acid in mg..

My home water is 6,5~9,5 ph so I have to test it every time..😪

if you know the ph of water, then you can adjust it without a ph meter. I have it, but I don’t use it because I already know by heart how many liters of water how many ph down i need. I use Ph Down from General Hydroponics. I also have 7 ph from the tap and for 10 liters of water you need 3 mlg ph down to make it 6.2

Yes 7 ph its good for flushing

What do you use?

If all you're doing is flushing the plant prior to harvest, pH is not going to matter... Vivosun is cheap and fairly reliable .... but only the rich can afford to buy cheap things because they have the money to keep replacing whatever cheap thing they've bought. Good luck!