i have been working with a 29gal bio cube tank for the past 8 months. i started with just live sand and live rock and saltwater for about a month. then put two blue/green chromis in the tank. from there i have had a large number of fish but all have seem to gone to fishy heaven. all but one. my blue damsel. i do about a 25% water change every week and for a couple weeks i would do 2-3 25% water changes. i add bio zyme and a API algae controller to help with the algae on the glass, once a week. i check ph,ammonia,nitrate,and nitrite. along with phosphates every so often. i run the lights that came with the tank but did to three days of lights out to help kill the diotomes that i had on my sand bed. i run two power heads and a protein skimmer. there is no refugeum or sump because i have no room. i have a R/O filter in the basement but wonder if it is of good quality because it is one that you can get at any local Lowes or Home Depot. also have a 4th filter for DI. On a weekly basis my levels stay about the same however my ammonia might be just above 0. i have never seen my nitrates or nitrites spike. specific gravity stays around 1.23-.25. if anyone could maybe give me some info on why my fish die off and i have diatoms and a algae problem still after 8 months. i would love to start to enjoy my tank. i am leaning to getting a group of assorted damesls and maybe one larger fish, such as a coral beauty angel fish in the future. have no desire to mess with coral. maybe in a larger tank years later.:frustrat: