Heard that before. I have big problems with chalk brood. first two hives i had, had chalk brood, they looked really poor, so i fed them a couple of times with tea and one hive is looking great, almost no chalk brood at all, i could say that it's cured. Then i got 3 more hives, they were swarms exactly, and 1 also had chalk brood. so 3 out of 5 had chalk brood. Someone told me to spray or feed the bees with apple vinegar, well i can say the bees aren't very keen about eating vinegar but the new hive got cured. so now i have only 1 hive with serious chalk brood problems, i've sprayed them with vinegar, so the next week i should see the results. I also bought some powder againts chalk brood, so i'm not very sure what helped 1 hive, either the powder or the vinegar treatment...
others say requeening is the only solution, others say that it ain't...
i've heard all the treatments and started with the cheapest :P , it helped, you go try you're luck.