Changing sand bed...

[Whiskey]

Have you seen a reduction in the number of inverts in your tank? Could the climbing nitrates be to the attrition of inverts and the decrease in associated cleanup?

I got the tank and stand out of the basement; lights are down from the ceiling. The tank isn't cleaned yet but if you get some time, give me a shout and we can get it over to your place.

[Cal_stir]

nitrates are a whole other animal, DSB's and macro algae fuges can't sustain med to heavy bioload systems on their own, some sort of denitrator is required, i have been running a sulphur denitrator sucessfully for over a year, my no3 is 0.5ppm on a heavily stocked 90gal mixed reef.
biopellets, zoevit, vodka dosing, and other forms of carbon dosing are good at reducing nitrates and some will reduce po4 as well, all have their pros and cons so do the research,
the new thing i've seen is a recirculating biopellet reactor where the effluent to the tank can be controlled preventing total strippage of all the no3 and po4, haven't seen the reactor on the market yet but it would be an easy DIY. waiting to see if it works long term.
if you have a DSB that has gone south then you should deal with that first.