I am new to Saltwater having purchased a used 265 gallon aquarium (used) from a local aquarist. I set up the tank exactly as he did, reusing his 120lbs of live sand and 250lbs of live rock. I even reused 100 gallons of his water only adding enough of my own new water to fill the tank to running capacity. The sump/refugium tank is 100 gallon but only filled halway with water and loaded with 40lbs of the live rock some of the live sand and a very large protein skimmer. The Serpent star, short spine urchin and Blue Banded Hermit he still had came with the tank as well as some sort of polyp that was still alive on one rock and some red leaf kelp. My tank cycled in just 2 days and I was able to add snails and hermits after 4 days to cut down the algae that started to grow. A week later I did a 70% water change and added a yellow tang, tomini tang and algae blenny. A week later I added Aussie Bubble Coral, Branching Hammer Coral, a Royal Blue Tang and 4 Cardinals. It's been about 5 weeks and now I have a Fire Angel, Coral Beauty, Clown Fish, bi-color Dottyback, brittle star, 2 Sally Light Foot Crabs, an Emerald Crab, an Arrow Crab, 2 Scarlet Cleaner Shrimp, a Banded Coral Shrimp, a Blood Red Fire Shrimp, a long spine urchin, a purple tipped Haitian Enemone, about 10 coral frags and two gorgonians. My current water measurements are 0ppm-ammonia, 8.0-PH, 0.0ppm-Nitrite and Nitrate varies from 20-40ppm. All of this being said, I would say I only have truly 270 gallons of water with everything that's in the two tanks. The protein skimmer does a great job and other than scraping a fine film of algae from the glass every other day, maintenance has been easy. I just changed out 60 gallons of water last weekend and noticed that the nitrate level did drop quite a bit the day after the change. So my questions are: How often and how much water should be changed? It seems like 50 gallons every other week is good. But is it good enough? Are more frequent changes at lower amounts better than one big one every other week? Also, even though the fish are relatively small for the size of my tank, have I got too many fish?
