Hi guys i keep gettin a foamy skin on the water surface of my aquarium?

i have the aquarium set up about 18 months now but in the last 4 months i got a kinda bacteria bloom or sometin it made the water seem cloudy grey 4 ages and would not clear up with water changes but when i left it alone it with no water changes it cleared up in 2 weeks but im worried it will come back again as i keep gettin this foam on the water surface and i dont understand why im getting it .i keep dwarf cichlids in the tank and i was wondering could this be as a result of them breeding and not knowing wot to do with the eggs and jus discarding them or wot could it be i must also mention that all the fish are healthy swimming around and up to there tricks as cichlids do yeno and i take tank matinaince seroiusly every 2 weeks water changes partial gravel vac and clean the filter if needed too if any 1 knows wot i shud do do tell me as iv bn lookin it up online and cant seem to find any answers to wot im lookin 4 any way tanks 4 looking guys