Ok, Here's the current situation for all you learners who are following the thread and trying to avoid the mistakes I've made:
The new sandbed is in, and looking pristine and wonderful. This time I know to watch for detritus build-up and keep the thing relatively clean, though stirring and siphoning doesn't appear to be allowed. As such I am going to stock the refugium with an assortment of detrivores to help churn the sand and keep the detritus eaten and processed. I plan to try ordering a detrivore kit from
www.inlandaquatics.com and see how that goes.
Nitrates are being kept down by 20 gallon water changes every two days. I figure my total water volume for the tank and refugium and plumbing is in the 140 to 150 gallon range after sand and rock is accounted for.
Snails and Urchins that were added are doing a great job of removing the nuisance algae, and that could also be contributing to the rise in nitrates. I expect the algae to be gone for all intents and purposes in another week. That is with 1 pincushion urchin, 1 tuxedo urchin, and 6 mexican turbos.
I also put in 4 emerald crabs, and I believe two of them died suddenly (possibly because of nitrates?) yesterday, but it could have been molting...can't say for sure. Flame scallop still appears to be hanging in there and appears healthy. I continue target feeding daily with phytoplankton and oyster egg and hoping the nitrates (which are at 15 mg/l now) wont be intollerable for it.
Have a fresh ball of Cheatomorpha in the refugium over the top of the fresh sandbed, and some bits of live rock rubble.
Bottom line: Deep Sand Bed of 4" deep oolitic sand in my refugium was definitely doing a lot of denitrification on the system, as I had just tested nitrates at 0 two days before removing it, and they tested at 25mg/l two days after removing it. Cheatomorpha would not keep up, hence the need to reintroduce a deep sand bed, however, I can't say if the system's bacteria would have eventually readjusted and overcome the nitrates or not. It's possible that leaving things alone would have been fine, but I like the deep sand bed for growing little critters in the refugium, so I went back to it.
Cyanobactera was receding quite a bit thanks to the mexican turbos, but eventually the receeding stoped, so I decided to go ahead and do a 2 day cyano-bacteria treatment with Chemi-Clean starting last night. Was probably a bad time to have to turn off the skimmer, and remove the activated charcoal and phosban, but I couldn't stand staring at the cyanobacteria any longer with the other problems finally clearing up. Tomorrow night, I will report on the state of the tank after turning back on the skimmer, doing a 20 gallon water change, and reinstalling fresh phosban and charcoal.
WHEW! This hobby can be demanding at times. *pant, pant, pant* Anyone about to get into reefkeeping needs to know what they're getting into!