substrate choices for sps

[Chicago]

have large reef sps dominated tank... oriiginally used fine sand 3 inches on bottom of tank... for asthetics only.. large sump in basment with plenum...

i need to replace this fine sand. the sand was getting blown around during feeding time and during the day with the currents.

i have been siphonng it out over the past months... i need to replace it. i started to go for the rubble bottom thing... so fast currents in this rubble would simply keep the detirtus suspended...

problem is these larger 4 iche pieces are ok in the back. towards the fort and in the rock work nned to add something smaller..

need this to keep the rock work stable..

i was thinking about going with the puca shell ... but noticed some strange black peices in it.. i assume they are safe.

other sugggestions on cool substrate is appreciated.

thanks

 

[surfjeepzx]

start mixing in crushed coral with your sand bed.

 

[Chicago]

that was a thought .....