Tank Maintenance - Seeking wisdom from the greats

[element291]

Hello everyone,

I have a 215 gallon tank with a 75 gallon sump, reef octopus regal 300 ext skimmer, and I have been checking my nitrates regularly to avoid any problems with my fish health.

I used to have a 75 gallon tank that I did water changes on every other week and it did great. I have since upgraded that to my 215G setup around May this year.

I have probably 350-400 pounds of rock and about a 3 inch sand bed, 4 inches in some spots. Tank temp usually 78-82 at its lowest and highest ranges.

I have got away with very low phosphates and next to no nitrates 0 ammonia to of course for about 2 month increments then my nitrates go up around 60ppm I change 80 gallons of water on the system.

Currently I have 1.023 salinity normal CUC few cleaner shrimp an urchin, crabs snails, sand sifting star, brittle stars along with a blue hippo tang, bunch of clowns, foxface, few chromis, goby to name the majority.

My corals have been doing great in my 75 gallon but in my 215 they all have noticeably stopped growing as well as my GSP that was covering many rocks is seeming to do fine on some rocks but totally dying and peeling right off the majority of them. My kenya tree shrunk up and withered away, my xenia was taking over a lot of rock in my 75 gallon but has since disappeared off many rocks and I only have a tiny bit left that looks fine but does not extend as much as it used to, nor is it growing at all anymore.

I know I changed params by stopping the frequency of my water changes.
I tried running a hanna calc test the other night and got 520ppm both tries which is pretty high from what I have read. I do not have an alk test kit which yes i know why test calc without alk, I need to get on this asap.

I run npx biopellets a skimmer, grow 4 mangrove trees, have cheato that never grows but maintains same size and stays nice and green though...

My tank is only 1 foot higher than my old tank I am using same lights that used to work great on my 75. I have kept the coral 1 foot away from the bottom of the tank to avoid any sitting in a low light spot and I am really wondering why 75% of my coral looks great but many of my zoas gsp and xenia are all crapping out (all the easy corals too! ARG) I have a huge frogspawn that looks great everyday, green button, big brain, umbrella coral, all look mint but these fast growing nice polyp corals are seeming to have a rough time...

Sorry for the novel but I really hope I have given the correct information to get me on the right track to some helpful suggestions.

I know I should be dosing if I am going for over a month with no water changes right? What is the best suggestion for a newbie to dosing? I plan to get an apex once I move into my new house Oct 21st.

Thanks for your time I really appreciate any assistance in getting my params up to snuff. I am more looking into dosing so I can save the large volume water changes involved with an approx 300G system.