"Mean_Chlorine" wrote in message
om...
Andy Hill wrote in message
. ..

Any idea what your KH was? It's remotely possible that the RO water
diluted an
already-marginal amount of buffering capacity to the point of causing
a pH
crash.

Yes, I considered that. The KH was about 3, but that was some time
ago. Anyway, I dissolved two heaping tablespoons (this is a 90 liter
tank) of bicarbonate in water and poured it in, but it's made no
visible difference.

The crenuchus now eat, but still 'twitch' now and then. Despite
repeated water changes and the bicarb, something is still not right,
but I'll be darned if I know what it might be.

I'm stumped.

I've pretty much decided to tear the tank down and set it up afresh,
with all new rocks, driftwood & sand.

All the inverts in there - tons of shrimp, snails, copepods, little
worms etc - look as happy as ever, otherwise I'd have suspected heavy
metal poisoning.

The missing number (or maybe I just missed it) is the gH. I've been
keeping pieces or coral (about the size of my finger) in many tanks
lately (even soft water fish). My kH and gH is about 2-3dH. I've been
doing this to increase the buffer, but after reading, now I'm starting to
worry about the gH. I occasionally hear about someone keeping fish in RO
water, but I don't know how they do it. Maybe their substrate or
rockwork is leeching.

Metal poisoning is a strong possibility, as is a heavy dosage of chlorine
or chloramines (during pipe maintenance). I'd be tempted to check with
your municipality and your local aquarium society.

NetMax