My tank has been up for a couple weeks now and I did a 35% PWC
a couple days ago after the cycle. It's a 28 gallon with 40 lbs LR
(mix of fully cured and pre-cured) and 10 lbs sand. Maybe 3 lbs of LR
rubble in rear sump filter basket. No other filters.
Twice now I've had my SG
actually drop using a refractometer and checking it also with a hydrometer because I couldn't believe it. When I first started it up, I had an SG
=1.024 that ended up around 1.020 after 2 weeks. Now 2 days after my PWC SG
has dropped from 1.023 to 1.022. I have not added any additional water to account for evap in either case.
Is my LR
and associated growths/hikers pulling enough trace elements from the water to actually lower my SG
. I'm using SeaChem Reef Salt if that matters. I expected SG
to always rise due to evap, never drop??? I was going to introduce some cleaner crew in the next few days, but now I fear the SG
drop might stun the crabs and shrimp.