Fill my plenum with LS or yank it out?

[1RockyHeap]

I've got UGF installed on one half side of my 6' long 135 gallon reef that is loaded with 250 pounds of LR and numerous soft corals. I have 2" of crushed coral substrate on top of the UGF with a no current dead water zone underneath. Time to make it a DSB.

I've bought 90 pounds of Caribsea sugar sized sand that I want to add over the UGF after syphoning out all the CC. I hate the thought of ripping out 1/2 my arranged reef LR, then the mess and ecosystem impact.

I don't want to disturb the nutrients underneath the UGF and release a whole slew of dissolved organics into the tank. I'm fighting diatom blooms and cyano break-outs (red, green, blue-green and black algae, I got 'em ALL!<grins>) plus I really don't want to start over and remove 100+ pounds of my LR and 20-30 corals......scary to even consider.

Can I siphon all the crushed coral out, leave the UGF filter plate, then add Aragonite sugar sized right on top of the UGF plate? I figure the ultra fine sand would seep through the .1" slits in the UGF filter plate, and would slowly fill the space beneath. What about the 2 years of accumulation of sediment under the UGF? Would that be "absorbed" and processed by the DSB?

Comments or suggestions? I've searched and search all archieves, and have a whole new level of respect for Thiel
Dr Ron. Thank you so much for your published and archieved reports.

Can I leave my plate in, remove all upper CC, then add the aragonite for a true DSB? I've also thought of trying to "siphon" any organics from under the UGF plate via a powerhead on a up lift tube that would pump the water out of the tank during a water change. After several buckets worth of this "dirty" water, I'd remove the up lift tube and cover the UGF with the DSB.

Thanks for your help Dr Ron, time to roll up the sleeves and "dig" in....

Time to start all over, or can I salvage what I have?

Rocky in Seattle.

[rshimek]

Hi Rocky,

Your tank will probably come out of this just fine.

Do siphon out the CC. I would advise against leaving in the UGF plate, but understand the problem fully. I would suggest cutting a few larger holes in the plate and siphoning out as much of the accumulated crud as you can.

If you can, when you are done removing stuff from under the plate, try to get some sediments under it. The DSB function is really dependent on filling in as many of the cavities as you can.

If you can do this, you should have a DSB that will function adequately. After all the disturbances, your tank will probably cycle a bit, and after that you should try to re-innoculate the worms and bugs with some sort of replenishment kit.

[1RockyHeap]

Thank you sir, for your prompt reply.

Too often we as aquarium reef keepers try to "take the easy or cheap way" out of a situation. From techniques or hardware purchases.

I'll get the plate out, or at minimum get it well clean out underneath, then fill as many voids with sand as possible.

Thank you once again for all your contributions to our reefing livestyle.

Rocky Heap