New tank... need help!

Jamie St.Thomas

New Member
I am new to this hobby. I bought a 400 gallon saltwater tank. I have a sump tank and a protein skimmer. I also bought 250 pounds of dry live rock and 160 pounds of live sand. I put two cat sharks and two sting rays in it. I cycled the tank for a month with some some damsels. My levels went high and came down so I was told my tank was good to go for the sharks and rays. Boy I was given some really bad advice. Everything was good for a week. Then my fish stoped eating. I checked my levels and everything was way high. I bought 20 pounds of ceramic rings, 70 pounds of live cured rock, and 2 buckets of matrix (the buckets are 4liters each). I also bought enough bio sipra to treat the tank aswell. My levels came down enough my fish are eating again but still a little on the high side. I have 3 marine pure blocks coming in the mail should be here on Sunday. Is there anything else i could do? Or is it just a wait and see and hope I don't lose any fish?


Well-Known Member
Water changes will help, as will adding Prime. Your tank was cycled, but putting in such a large bioload at once overwhelmed the relatively small bacterial population you had established. Take some time to let things settle down while making regular water changes. If ammonia levels rise ad Prime. Otherwise, just wait it out. Now you know what we mean when we say that nothing good happens quickly in this hobby. By the way, "250 pounds of dry live rock" is another way of saying 250 pounds of dead rock, so your bacterial population was way to small to begin with. It will become adequately "live" with time.


Well-Known Member
Bigger the change less often, or more frequent smaller ones. For a 400gal tank i would do either 30-40 weekly or 80-100 biweekly depending on bioload


Active Member
Man did you look before you leaped on this one. Sharks and Rays are by far the hardest thing to keep in aquariums and I sure can't imagine having them in my first tank. Sharks and Rays are very sensitive to nitrates and honestly 2 catsharks and 2 rays is way overstocked for a 400 gallon. What kind of catsharks did you get and what kind of rays did you get? If you got the coral or the australian marbled you will be fine with a pair of them in the tank. For the rays if they the California variety then a pair would be fine but not a pair of each. If you got the banded or bamboo variety catsharks then you will only be able to keep them for a limited time as a pair of them would outgrow that tank. They are massive waste producers and voracious/messy eaters which will all contribute to waste and destabilizing your water perimeters.