Sorry the hear about the shrimp and algae outbreak. One thing you might want to try is passive CO2. basically invasive co2 the diffuser is replaced by an inverted bell or container iwht no air init . it is then filled with CO2 the CO2 naturally diffused into the water. it is impossible to kill fish and shimp with passive CO2 since any excess will bubble up to the surface and dissipate before it can do any harm. So you don't need a drop checker to measure CO2, and in fact drop checkers don't work with this system. But I ca still see bubbles of oxygen on the leaves. it is also much more efficient meaning your bottle of CO2will last longer. Many people refill the bell once a day or as needed. I was able to carefully adjust my co2 to a very slow flow allowing a timer to automatically fill it to keep a small bell full of CO2.