I have noticed Ca/Sa cichlids not liking the water in North America during the cold months. My guess is the dissolved gasses??? Once the water starts to warm up (which naturally causes dissolved gasses to "gas out") they start to explode. Long story short, change more water in the spring and summer for max growth. Change water in the winter to keep nitrates at bay. I like a smooth growth rate, so I do not change water everyday in the hot months anymore. although it is so tempting. Hope this helps.