yes. kno3 (nitrates) will provide potassium as well as kh2po4 (phosphates) which will provide potassium. u may need extra k since u have liquid ferts and im not sure what they use for nitrates and phosphates. they can be derived from other substances
phosphates can definitely cause holes in leaves. color issues. leaves that fall of early. and poor plant growth in general. plants usually tolerate low amount well. but some don't
i'd get a more regular fertilizing routine as that is the EASIEST thing to control.
plants will respond well to this.
THAT being said it will also show u where other imbalances are. once fertilizers are non limiting. if u have c02 or light issues. algae will rear its ugly head. you will blame fertilizer saying it caused algae. that phosphates did it or excess iron. these things are not true. i keep 5 ppm phosphates in my tank and roughly 20 ppm nitrate. i don't have many algae issues other than what i cause from changing c02 and light lvls and that is the occaisional spot of black algae