Eating my coral?

[DKoKoMan]

Originally Posted by BCOrchidGuy

Thanks for all the advice, like I said I did a bunch of large water changes 50% to 75% a couple of times and 25% 4 or 5 times.

Tank is about 2 years old, all other paramaters being maintained fairly steady.

Regarding checking the test kit, I would test my new mixed water just incase I had nitrates coming in with the tap water but nitrates were zero. After a large water change my nitrates would be on par with what percentage of water I changed but within a day or two the nitrates were over 100 again.

I have not checked phosphates but I will purchase a test kit tomorrow.

Thanks for all the input

The phosphate number will give a better look in to the balance of nitrates and phosphates. Once this is determined you should be able to correct the issue.

[BCOrchidGuy]

PO4 is unreadable, effectively 0
NO3 25
pH 8.03
Salinity 1.024
Ca 400
Mg 1300
Alk 8dKH

This is after I moved everything into a new tank almost 3 times the volume of the old system. I went from a 25 gallon with a sump to a 75 gallon with the same sump that I calculate to hold about 15 gallons. I moved about 10 - 15 gallons of the old water and all the live rock to the new system after it was all rinsed.

Coral isn't getting worse, LPS is all open and actively feeding, SPS is ... to be determined. Zoas are all happy except for one colony so it may be light or some irritant, I'm going to move that colony. My three rbta seem happy, one moved to a more happy location.
Seeing a few pods skittering in the rock too.

[Frogger]

Your corals that photosynthesize require both nitrogen and phosphorus at a specific ratio to complete the process. If one is limiting the process is stopped or reduced. This will cause the other one to artificially increase because the zooxanthellae, algae and other photosynthesizing organisms don't have enough of the other to continue. Your tank may not have 0 phosphates however any new phosphates that are added via food, additives or fish poop is quickly used up.

This sounds like it is a distinct possibility in your tank. You have enough phosphates to keep the corals alive but not enough to use up the nitrogen or to make your corals happy.

SPS are the most affected because zooxanthellae are their primary source of food.

[tang daddy]

I would try to feed more to get the Po4 up. Last I checked my po4was .11 and sps are thriving....

My success is mainly due to the heavy feedings with a ton of fish.
I haven’t tested nitrates for awhile but I assume that it’s over 10.
I may do a large wc this week to reset the Po4 to half but reluctant to touch anything while the tank is thriving.

Try feeding more and see if that helps your sps!