[tang daddy]

You actually had a tank journal, just saw it now. Tank looks amazing, how are your corals doing with the high nitrate? Lps super happy? How about sps?

Even though you have a low sandbed maybe possible that it could be leeching?

How much rock do you estimate you have?

Your feeding seems ok but if you are putting a lot of food in and some of the food gets missed or not eaten that could definately play a role on the nitrates creeping up. Bp may lower nitrates but only to the extent that it can lower phosphates. Once there is an imbalance you may start to see cyano bacteria.

You may also want to try siporax to lower nitrates, as I've heard it is great results. 15g water changes is better than no waterchanges but if your nitrates are through the roof it may not be any harm to do some larger wc like 80g.
If it's possible.

I haven't measured nitrates in my tank yet but don't have a lot of rock in the display, also only started with a few lbs live and the rest was cooked rock. I will be starting siporax soon for extra filtration to break down the nitrates, I just need to get a hold of a large canister like a fx6 or and ehiem 2250.

I feed my tank heavy 2 times a day as I just added some anthias.

But if it was me I would try a large wc then test the next week to see where I am at, as this seems to be the easiest adjustment to do now.