ok i did the water change and hopefully everything is fine. One more question i bought some snails, crabs and shrimps like 2 weeks ago. i noticed that some of the snails and crabs have died off is this normal i think i had about 50 or so snails and crabs i think about 10 have died. also should i keep the sun bulb on during the day or should i put the sun bulb on with the blue bulb during the day.?