my clams keep dieng i have 260 pcs on a 55 g all my aprametors are right cla 450 ppm and feed the dts i had a puprl/blue maxima3.5 inches and a gold maxim2.8 inches. the died at diffrent times but b4 they died there foots were not attached to the sand the foot was either ripped or not atched could it be a lightin issue the y were in the sand bed