Hello, at present in my tank are ph:6.1 and dkh:5º,it a lot of co2??According to the tables I have 93 mg/l of co2, the fishes do not gape, can it be possible??? tank 99gal. Why does he be recommended to always 30 ppm?? For the fishes?? If it be possible to increase the concentration of co2, serious bad guy for the plants so much co2??Thanks..