"jthread" wrote in message ...
I decided not to put the paver sand or play sand because I thought it would
be ugly and I'd regret it in the long run. I put the Aragonite right over
the old sand. I hope that's OK. Looks real nice now but I have a skylight
there and it likes to grow red slime on the sky light side. Any pointers on
getting rid of it (the slime) are appreciated.

Measure phosphates with a electronic photometer...
If you have anything in the range of 0.05-0.09
than you have too much phosphates and you should
use phosphate removers.