The last 2 brew days have turned a bit of a marathon due to my Tesco elements farting out , the first time both stopped at 80c , I finished off the brew with a smalller tea urn, I scrubbed them thoro the next time only one farted out, again when cleaning after both were coated in , the reason I can think of is that both were overnight brews, and also I let the pump suck the mash dry, I think I may have brought some fine grain into the boiler, and it settled on the elemnts, anyone come across this , do I need to replace the elements or will a citric acid bath solve it , maybe running the sort through the hopfilter in the kettle b4 starting the boil