When adding new water to my tank I've always put in both Prime and these water conditioner blue crystals, as that was what I was sold when I bought my first tank and I never questioned it. But I'm not wondering if I actually need to use both, or if Prime would be enough? The crystals never really dissolve properly, I'd like to stop using them if I could 
This is what I've been using -
This is what I've been using -
