2 chemistry questions
1) When I do a water change there's no gas buildup inside my CO2 reactor (it's a DIY venturi reactor). This happens for 1 or 2 days after the water change. I don't think that my plants are using all this CO2 (it's a 20 gal tank with 1-2 bubbles per second). Why? I use tap water dechlorinated with sodium tiosulfate (it's a 1/2 tsp sodium tiosulfate in 100 ml of water solution, I dose 5 ml per 25 gallons of tap water one day before water change).
2) I dose KHCO3 (potassium bicarbonate) to raise my KH and dose it dry after water changes and when I dose CaSO4.2H2O or MgSO4.7H2O I can see some bubbles. What's the chemical reaction?